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5 System Investment Needs: A 20-Year Horizon As the Interstate Highway System enters its seventh decade, the proposi- tion that it can continue to serve the country effectively for many more years without extensive renewal and modernization is unsupportable. Much about the future is unforeseeable, particularly beyond the next two decades, given that, as discussed in the preceding chapter, advances in technology and changes in climate have the potential to affect the system in profound but still indeterminate ways. Yet, despite this uncertainty, the systemâs future over the next 20 years or so is not imponderable. Over this period, the system can reasonably be expected to experience increasing demand in line with a growing population and economy, with much of this demand taking place on urban segments of the Interstate System that are already heavily used. A safe, reliable, resilient, and well-functioning Interstate System is almost certain to be needed to accommodate traffic growth over the next two decades and beyond, but is plausibly even more critical to ensuring that the benefits of technological advances can be exploited and vulnerabilities to climate change can be minimized over the longer term. A medium-term investment strategyâone targeted to the more foreseeable future of the next two decadesâthat renews and modernizes the systemâs aging and worn pavements and bridges and aligns and allocates capacity in anticipation of growing traffic demand can be viewed as fundamental to the longer-term interest of preparing the Interstate System for the opportunities and chal- lenges deeper into the century. The focus of this chapter is on defining the core elementsâand as- sociated investment requirementsâof a 20-year strategy for renewing and 127
128 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM modernizing the Interstate System under various, historically informed as- sumptions about plausible traffic growth. The average annual investment required for some of these elements can be approximated using available modeling systems, while that for other elements cannot be quantified as readily because of a lack of data, modeling capabilities, and other relevant information about the specific actions required to address them. In this regard, the dollar estimates presented herein can be viewed as minimums. Although the explanation of how these estimates were calculated consumes much of the discussion in this chapter, the investments in areas identified in the chapter that are unaccompanied by annual spending estimatesâsuch as rebuilding interchanges and increasing system resilienceâshould not be viewed as being of lower priority. GENERAL APPROACH FOR ESTIMATING INVESTMENT NEEDS At a Glance â¢ Standard Federal Highway Administration (FHWA) models for estimating highway and bridge investment needs are used as the main basis for approximating the investment levels required to renew and modernize the Interstate Highway System over the next 20 years, assuming alternative rates of traffic growth. â¢ Whether an investment is categorized as âneededâ depends on the highway condition and performance outcomes that are desired or considered acceptable by decision makers. While such outcomes are subjective, the estimates developed in this chapter are derived from modeled benefit-cost calculationsâthe approach recom- mended by Congress in requesting this study. â¢ The estimates presented herein are intended to provide general guidance to decision makers on the magnitude of investments required over the next 20 years. To define the core needs for renewal and modernization of the Interstate Highway System over the next 20 years, and to approximate the average annual spending required to meet those needs, the committee employed the Federal Highway Administrationâs (FHWAâs) standard modeling tools, supplemented by other information and methods when the models were judged to be insufficient. This approach is consistent with the legislative re- quest for the study, in which Congress recommended the use of the analytic methods proposed in the report of the National Cooperative Highway Re- search Program (NCHRP) Project 20-24(79), Specifications for a National
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 129 Study of the Future 3R, 4R, and Capacity Needs of the Interstate System (Miller et al. 2013). That report recommends use of the FHWAâs modeling systems for highway and bridge investment needs (described below), supple- mented by information derived from case studies of Interstate projects, for predicting investment levels needed to attain prescribed performance and condition outcomes under different assumptions about future Interstate traffic growth. The term âinvestment needsâ warrants explanation as used in the con- text of this report. Whether an investment is âneededâ depends on what outcomes one desires or considers acceptable, such as how much pavement smoothness is desirable or how much traffic delay is acceptable. Because determinations of outcomes that are desirable or acceptable to the public are subjective, it is obviously not possible to make definitive estimates of âneededâ levels of public spending. However, Congress specifically directed the committee to conduct its analyses and use its judgment to recommend investment levels informed by the methodology proposed in the NCHRP report. As noted above, a key component of that proposed methodology is FHWAâs modeling tools for highway investment needsâthe Highway Economic Requirements System (HERS) and National Bridge Investment Analysis System (NBIAS). FHWA uses the models in its biennial Conditions and Performance (C&P) report to Congress (FHWA 2016a). The C&P re- port thus provides Congress with approximations of the overall investment that will be needed over a period of time to achieve certain condition and performance outcomes and enables assessment of how alternative invest- ment levels will affect these outcomes, or vice versa. The approach used in this chapter for estimating 20-year investment levels is a derivative of the methodology proposed in the NCHRP report. The committee developed these estimates using the recommended models by applying a range of projected rates of growth in motor vehicle travel. The results are limited by the coverage and design of the databases used in the models to depict the current condition and performance of the highway system, as well as a number of other factors described below. Neverthe- less, the committee concluded that HERS and NBIAS can be informative regarding the magnitude of investments that will be required to renew and modernize the Interstate System over the next 20 years, and that the methodologies and output of these models have the important advantage of being familiar to decision makers, including Congress. Because HERS and NBIAS are designed to consider standard options for improving pavements and bridges, they need to be supplemented with other data and tools to enable a fuller consideration of improvements that can be made to the system. The chapter examines some additional improve- ment options applicable to the next two decades, such as the construction of special-purpose tolled and truck-only lanes. The chapter also contains a
130 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM brief discussion of the improvements that will eventually be needed to add resilience to the system and modify its length and scope to accommodate a changing geography of user demand, a discussion that is necessarily limited because the committee could find no reasonable basis for estimating the cost of making these improvements over the next 20 years. Before considering the annual spending that will be needed for Inter- state System renewal and modernization over the next two decades, the chapter considers spending on the system over the past two decades as con- text for the nature and scale of the investment that lies ahead. This review is also important for understanding the starting point for future investments, which includes a backlog of highway and bridge repair, replacement, and capacity expansion and management needs. RECENT INTERSTATE CAPITAL SPENDING AND THE INVESTMENT BACKLOG At a Glance â¢ In 2014, $25 billion, including both state funds and federal aid, was expended on the Interstates. Of this amount, $20 billion was allocated to improvements to pavements and bridges; $2.2 billion to new construction and relocation projects; $1 billion to major widening projects; and the remainder to traffic operation and control systems and safety and environmental enhancements. â¢ While states have gradually increased their spending on pavement surface repairs and rehabilitation, spending on full reconstruc- tion of pavement foundations has remained relatively unchanged despite a growing inventory of pavement structures that have exceeded their original design lives. â¢ Even if future traffic volumes and loadings grow modestly, tens of billions of dollars in pavement renewal and modernization work that has been deferred will be coming due over the next 20 years. In 2014âthe most recent year for which complete and detailed capital spending data are availableâstates spent $25 billion, including their own funds and federal aid, on the Interstates. Of this amount, $20 billion went to improvements to existing pavements and bridges, $2.2 billion to newly constructed highways and bridges, and $1 billion to major widening proj- ects. The remaining spending, recorded as capital investments, funded traffic
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 131 operations and control systems and safety and environmental enhancements (FHWA 2016b, Table SF-12A). These figures do not include spending on day-to-day maintenance activities, such as snow and ice control, pothole repair, and mowing of medians and other rights-of-way. These latter expen- ditures are not classified as capital spending and are not considered in this report, except to recognize that such maintenance activity and its costs are affected by capital investment choices. Total capital expenditures on the Interstates in 2014 are largely indica- tive of the magnitude of spending over the previous two decades, but with some exceptions. Figure 5-1 shows state expenditures (in 2016 dollars) on pavement-related projects for the 17-year period 1998â2014 as recorded by FHWA. (When this report was being developed the most recent complete data on spending was for 2014.) Evident in this figure is a large increase in spending in 2011, the result of the one-time augmentation of federal-aid highway funding authorized under the 2009 American Recovery and Re- investment Act. Also evident, however, is the gradual increase since 2004 in spending on pavement rehabilitation, which includes surface repairs, resurfacing, and similar restoration and preservation work. FIGURE 5-1 State investments in pavement reconstruction, resurfacing, rehabilita- tion, and restoration of Interstate highways, including federal aid (in 2016 dollars, using gross domestic product [GDP] price deflator). SOURCES: FHWA 1999â2015, 2016b. $0 In ve st m en t, M illi on $ Reconstruction with added capacity Reconstruction with no added capacity Resurfacing $2,000 $4,000 $6,000 $8,000 $10,000 $12,000 19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 20 06 20 07 20 08 20 09 20 10 20 11 20 12 20 13 20 14
132 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM The most common pavement rehabilitation procedure is to replace the surface course through resurfacing, which is typically done with an asphalt overlay.1 In 2014, this spending category accounted for about two-thirds of state pavement-related expenditures, compared with previous highs of 57 percent in 2000 and 63 percent in 2010. Most of the increase in to- tal pavement-related expenditures during the 17-year period, which have grown in real terms by 50 to 70 percent since the mid-2000s, stemmed from increases in spending on surface treatments. By comparison, spending on pavement reconstructionâincluding projects with and without accompa- nying capacity additionsâremained relatively unchanged over this period. Pavement reconstruction goes beyond adding overlays and fixing surface deficiencies, and almost always involves replacing the pavement structure with new materials. This spending category includes, but does not identify the amount spent on full-depth reconstruction, which involves replacement of the pavement surface and base and stabilization or regrading and com- paction of the subbase. Figure 5-2 shows annual state capital expenditures over the same 17 years for Interstate bridge work. Here again, the sudden spending in- crease due to the American Recovery and Reinvestment Act can be seen in 1 Typically this treatment would include replacement of spalled or malfunctioning joints, substantial pavement stabilization prior to resurfacing, grinding or grooving of rigid pave- ments, and replacement of deteriorated material (see FHWA n.d.-a, Chapter 12). FIGURE 5-2 State investments in Interstate highway bridge replacement and re- habilitation, including federal aid (in 2016 dollars using gross domestic product [GDP] price deflator). SOURCES: FHWA 1999â2015, 2016b. Bridge replacement Bridge rehabilitation 19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 20 06 20 07 20 08 20 09 20 10 20 11 20 12 20 13 20 14 $0 In ve st m en t, M illi on $ $1,000 $3,000 $4,000 $6,000 $7,000 $8,000 $2,000 $5,000
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 133 2011. Otherwise, however, annual bridge spending in real terms was stable throughout the decade preceding 2014. Finally, Figure 5-3 shows capital spending on new highway and bridge construction during the same 17-year period. In this case too, the trend has been one of flat or slightly declining annual spending, at least when investment levels from the 2010s are com- pared with those from a decade earlier. Despite this capital spending on the Interstates, which has averaged about $20 billion per year (in 2016 dollars) since 1998, the system is not in pristine condition, and investments deferred in the past will need to be made in the future. These future investments will be accompanied by required spending for repair, reconstruction, and expansion resulting from the systemâs ongoing aging, wear, and use. In its 2015 C&P report, FHWA calculated that in 2012, a $145 billion backlog of investment needs would need to be liquidated to bring the system up to economically justified levels of condition and performance. Table 5-1 provides a detailed breakdown of this estimate and updates the calculations to 2016 based on system condi- tion and performance data for that year as derived from FHWAâs Highway Performance Monitoring System (HPMS) and National Bridge Inventory (NBI). The 2016 calculations suggest that the pavement backlog decreased, presumably in response to recent increases in state pavement investments shown in Figure 5-1. The bridge backlog, however, increased, along with the backlog of needed capacity additions.2 2 The increase in bridge backlog from 2012 to 2016 demonstrates that a linear increase in annual investment does not result in a linear improvement in the level of backlog from year to year over that same period. This a reflection of variations in age, condition, and rates of deterioration among the bridges in the inventory. FIGURE 5-3 State investments in new construction and relocation of Interstate highways and bridges, including federal aid (in 2016 dollars using gross domestic product [GDP] price deflator). SOURCES: FHWA 1999â2015, 2016b. New Construction Relocation New Bridge Construction Total new construction $0 In ve st m en t, M illi on $ $1,000 $2,000 $3,000 $4,000 $5,000 $6,000 19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 20 06 20 07 20 08 20 09 20 10 20 11 20 12 20 13 20 14
134 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM Although the types of work required to reduce these backlogs have changed somewhat over time, the total has remained at about $150 billion. As will be discussed below, this figure does not fully account for the spend- ing that will be needed to reconstruct aging and deteriorating pavement foundations, whose condition is not tracked by HPMS. Prospectively, it would be unrealistic to believe that an Interstate high- way investment strategy for the next 20 years could reduce this backlog quickly. In fact, much of any future spending to renew and modernize the Interstate System will have its origins in past decisions to defer reconstruc- tion work and capacity additions. Future growth in traffic demand and its impacts on the systemâs pavement condition and operating performance will be an important determinant of future investment needs, but not the only determinant. Indeed, even if traffic volumes and loadings grow modestly, it can be said with reasonable assurance that tens of billions of dollars in renewal and modernization work deferred over the past several decades will be coming due. MODELING TOOLS AND ASSUMPTIONS USED IN ESTIMATING FUTURE INVESTMENT NEEDS Modeling Capabilities and Limitations HERS and NBIAS can be used to assess investment needs from more than one perspective. They can, for instance, answer such questions as what level of spending is required annually to maintain and improve pavement and bridge conditions and operating performance over a period or what levels of system condition and operating performance can be achieved over a period with a given amount of spending. To answer such questions, HERS and NBIAS monetize the benefits and costs of a set of candidate TABLE 5-1 FHWA Estimated Interstate Investment Backlog Year Rehabilitationa Capacity Expansionb TotalPavements Bridges Total 2016 $50B $44B $94B $55B $149B 2012 $62B $40B $102B $43B $145B a For pavements, rehabilitation involves resurfacing and surface layer reconstruction. b In the context of analysis of investment needs, system expansion refers to added lanes. SOURCE: FHWAâs (2016a) C&P report, based on 2012 data and updated to 2016 using that yearâs data and the same methods.
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 135 improvements and calculate their impacts on aspects of system condition and performance. Box 5-1 lists the categories of benefits and costs monetized in HERS, as well as the measures that are used to calculate condition and performance. Monetized benefits include impacts on motorists (e.g., travel time, vehicle operating costs, safety) and society (e.g., emissions), as well as savings in highway agency maintenance and operating budgets. Monetized costs comprise exclusively expenses incurred by agencies in implementing an improvement, including acquiring right-of-way and hiring contractors to perform the work. Condition and performance measures include indicators of pavement surface condition (e.g., smoothness or roughness) and operat- ing performance (e.g., ratio of peak volume to capacity, absolute delay). BOX 5-1 Costs, Benefits, and Condition and Performance Categories in the Highway Economic Requirements System (HERS) Benefit Categories Considered â¢ Changes in user travel time costs â¢ Changes in vehicle operating costs (fuel, oil, tires, maintenance, depreciation) â¢ Changes in crash costs â¢ Changes in pollution costs (combined costs of carbon monoxide [CO], nitrogen oxide [NOx], particulate matter [PM10], volatile organic com- pounds [VOCs], sulphur oxides [SOX], and road dust) â¢ Changes in agency highway maintenance and operations investments Cost Categories Considered â¢ Initial right-of-way acquisition â¢ Construction costs Condition and Performance Categories (before and after improvements) â¢ Measures of congestion (ratio of peak volume to capacity) â¢ Speed by segment and averaged by functional class â¢ Delays â¢ Pavement condition indices â¢ Miles of selected roadway improvements â¢ Deficiency ratings for geometric features â¢ Crash rates â¢ Fatalities SOURCE: TRB Transportation Economics Committee n.d.
136 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM Clearly such a limited set of monetized benefits and costs cannot ac- count for all societal and economic impacts and their incidence, nor can the measures of system condition and performance include all criteria that may be of interest to highway users and policy makers. Furthermore, nei- ther HERS nor NBIAS considers all types of potential highway and bridge improvements or the broader set of options at the disposal of policy mak- ers for achieving a specific desired outcome. Some of the missing options may be more cost-beneficial than those considered in the models. Examples of options not considered to address capacity-related deficiencies include building an entirely new highway; adding high-occupancy toll (HOT) lanes or other forms of managed lanes; implementing reversible lanes; instituting policies that would reduce the demand for Interstate travel, such as land use restrictions; and investing in public transit to accommodate growing de- mand on the existing highway system. Similarly, a range of safety improve- ments are not considered. Safety is considered to be improved in HERS only if wider lanes, wider shoulders, and curve and grade flattening are introduced. HERS does not consider removing unsafe geometric features, such as short acceleration and deceleration ramps. With regard to pavement condition, a highway improvement that is not considered by HERS is the option of full-depth pavement reconstruction. Additionally, the HPMS database used by HERS to ascertain current system condition and performance consists of a large sample of individual highway segments. Accordingly, when HERS calculates the benefits and costs of an improvement, it does so for each segment independently rather than over a longer route or corridor. The same is true for NBIAS, which considers the benefits and costs of each bridge improvement in isolation. The models, therefore, cannot capture the upstream or downstream âcou- plingâ effects of changes to a given highway segment or bridges. Finally, for both HERS and NBIAS, demand is an exogenous input not derived within the models. The user specifies the level of vehicle-miles trav- eled (VMT) growth, for instance, to estimate the future need for capacity- related improvements. This means the models do not account fully for the effect of capacity changes on VMT itself. Changes in travel behavior in response to capacity additions are commonly referred to as âlatentâ and âinducedâ travel demand. The former term is used most commonly to describe the increase in traffic volume over what otherwise would have been expected from improvements to a facility as travelers take advantage of the faster travel speeds. For instance, travelers may divert from other routes or transit. Moreover, the improved traffic conditions (e.g., travel speeds and reliability) resulting from the increase in highway capacity may allow existing travelers to make additional and longer trips. Over the
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 137 longer term, increased highway capacity may improve the accessibility of a region, stimulating economic and land development and thus encouraging the generation of new trips, or inducing demand. Conversely, as conges- tion increases when capacity becomes constrained and is not increased, some travelers may change their behavior to avoid the resultant delay, in which case the overall effect will be to suppress travel demand to a degree. In short, any capacity increase (or reduction in the cost of traveling on the highway) will increase travel, while any capacity reduction (or increase in the cost of traveling on the highway) will decrease travel. HERS contains demand elasticities as a way to control partially for the effects of supply conditions on demand.3 Improved facilities are assumed to experience a bump in VMT growth rates that will offset some of the delay savings, while unimproved facilities are assumed to experience suppressed VMT growth in response to increasing levels of congestion. The latter fea- ture prevents unconstrained traffic growth in the face of congestion that would otherwise be expected to impede traffic volumes. Many metropoli- tan planning organizations and state departments of transportation have developed travel demand forecasting (TDF) models that address, at least partially, the interaction between travel demand and system supply condi- tions. These TDF models usually estimate the VMT effects from short-term behavioral changes by accounting for changes in routes, modes, and desti- nations. Some more sophisticated models also account for shifts in travel times. Rarely, however, are the longer-term induced-demand effects ad- dressed by the models because of the difficulty of predicting how changes in supply will lead to changes in land use and the resulting changes in traffic. The committee concluded that existing TDF models do not offer the national- or regional-level prediction capabilities needed to assess system- level impacts from Interstate investments. Importantly, these models, like HERS, could not be used to account for the redistribution of traffic on the system or other travel routes and modes. Because there are no existing tools with which to analyze these demand responses at the transportation network level for the entire country or regionally, the only alternative was to consult the recent history of travel behavior as indicated by past VMT growth rates to develop a reasonable range of future VMT growth rates to apply to the HERS and NBIAS models. The choices of VMT growth rates are discussed next. The limitations of HERS and NBIAS, as discussed in this section, are summarized in Box 5-2. 3 Demand elasticity refers to the percentage change in travel demand divided by the associ- ated percentage change in the price of travel, which can be measured in terms of travel time or the total cost associated with travel.
138 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM BOX 5-2 Applicability of Highway Economic Requirements System (HERS) and National Bridge Investment Analysis System (NBIAS) Modeling Systems to This Study The legislative request for this study called for the use of the Federal Highway Administrationâs (FHWAâs) HERS and NBIAS models to estimate the invest- ment required to restore the Interstate Highway System to its premier status in the countryâs transportation system. The committee understood that these two models were designed largely for the purpose of informing Congressâs deci- sions about future investment needs for the federal-aid highway program in the aggregate, as opposed to informing decisions about investments in individual assets (which are made by states). Although the committee identified limitations in the two models for the specific purposes of this study, as summarized below, it concluded that those limitations are manageable, and that alternative model- ing capabilities with greater relevance do not exist and could not be developed specifically for this study. Both HERS and NBIAS are built off databases that sample (Highway Perfor- mance Monitoring System [HPMS]) or survey (National Bridge Inventory [NBI]) the current condition and performance of segments and structures on the Interstate System. Having such baseline information on current conditions and performance levels is essential for testing the effects of different levels of spending on different types of highway improvements under changing traffic levels. A limitation of HERS in this respect is that HPMS, the database on which it is based, does not contain information on the condition and performance of Interstate highway interchanges and pavement foundations, which are major cost components of the system. Another limitation of the models is that they assume that rates of traffic growth are largely exogenous to the modelsâ output; the model user must specify traffic growth rates. Ideally, the traffic growth rate and pattern would respond to the predicted changes in system condition and performance and lead to changes in traffic extending beyond the improved segment. HERS and NBIAS lack this capability to model responses over a system and with feedback, which can be a particular problem for estimating effects over longer time horizons when demand and supply conditions are more variable and interact. The models test the effects of a limited set of improvements. They cannot be used to assess the impacts of a new facility, and they do not consider all system pricing; technology deployment; and configuration options available, such as the conversion of lanes for special purposes (e.g., high-occupancy vehicle [HOV] and truck-only service). The models calculate a limited set of benefits and costs of investments (outlay expenses and benefits and costs arising from changing conditions), rather than societal benefits and costs. As the unit of interest (e.g., all downtown freeways in large metropolitan areas) becomes more granular, the models use fixed parameters that may not be applicable, and the outcomes are not sufficiently context-specific. In the investment needs analyses presented in this chapter, these modeling limitations are noted, and some cases are compensated for.
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 139 Assumed Future Rates of Growth in VMT To use HERS and NBIAS to make estimates of Interstate investment needs, it is necessary to specify future rates of VMT growth as inputs to the models. While the current state of the Interstate Highway System is a major determinant of future investment needs (as noted earlier in discussing the investment backlog), future traffic volumes will add to these needs as a consequence of added pavement and bridge loadings and wear and new capacity demands. Because neither HERS nor NBIAS differentiates between the traffic growth rates of passenger cars and trucks on pavement and bridges or their relative loadingsâwhich is a notable deficiency of the modelsâonly a composite rate of growth in VMT (combined passenger car and truck travel) can be specified.4 Even if the models did allow for more granular VMT specificationâsuch as for local, interregional, and longer-distance Interstate tripsâthe data available for developing such input are limited. For example, the U.S. Department of Transportationâs (U.S. DOTâs) American Travel Survey, the only national-level database on longer-distance travel that includes highway trips, has not been updated in more than 20 years. As discussed in the previous chapters, highway planners have had mixed experience forecasting VMT. Planning of investments in long-lived transportation infrastructure, however, requires VMT forecasting. How- ever, even for a period of 20 years, such forecasting presents challenges. The magnitude, location, and timing of changes in travel demand will depend on a host of factors related to changes in the population and economy, how travelers respond to congestion and the supply of new capacity, whether new capacity is restricted to specific users, and the availability of options other than Interstate travel. Transportation agencies, especially in urban areas, may substitute more active operations and demand management measures, such as congestion tolling, which will affect travel demand levels. Although connected and automated vehicles are likely to have limited ef- fects on travel demand in the nearer term, some impacts may be observed in 15 to 20 years. Informed by the resource paper prepared by Polzin for this study (see Appendix C), the conclusion reached in Chapter 4 is that VMT growth ranging from 0.75 percent to 2 percent per year is a reasonable expectation 4 Although the modeler cannot specify different VMT growth rates for passenger and freight vehicles, both models account for passenger and truck weights and loadings when performing impact analysis. The HPMS database, for example, includes truck percentages for single units and combinations for every highway section, and HERS assumes typical loading patterns for trucks as well as for passenger vehicles.
140 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM for the next 20 yearsâcomparable to trends observed in recent decades and corresponding to the countryâs projected population gains, factoring in expected economic growth. This report uses a midrange or ânominalâ VMT growth rate of 1.5 percent, with low and high excursions of 0.75 and 2.0 percent, respectively, which the committee believes to be reason- able lower and upper bounds (see Figure 5-4). The lower bound might be more representative of future experience in locations where steps are taken to manage demand more aggressively, such as through congestion pric- ing on heavily trafficked urban routes. The higher bound might be more representative of future experience in locations where chronic congestion is not a problem today but where travel demand is growing because of population increases and economic development, such as in emerging metropolitan areas. Methods for Calculating Needed Investments As discussed above, HERS and NBIAS calculate the costs and benefits of Interstate improvements assuming different rates of VMT growth that place FIGURE 5-4 Total annual Interstate vehicle-miles traveled, historic since 1985 and projected after 2016, based on assumed growth rates. SOURCE: FHWA 2017. 0 200 400 600 800 1,000 1,200 1,400 1985 1995 2005 2015 2025 2035 VM T (B ill io ns ) Year Total Annual Interstate Vehicle Miles Traveled (VMT) VMT Low (0.75% annual) Nominal (1.5% annual) High (2.0% annual)
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 141 demands on the system. For example, in HERS the benefits of a candidate improvement are measured in terms of the savings to users (lower travel times, improved safety, and reduced vehicle operating costs, such as fuel, tire, and vehicle depreciation costs); to highway agencies (lower mainte- nance costs); and to society (savings in the costs associated with emissions). These monetized benefits are then compared with the outlays required for making the improvement, computing a benefit-cost ratio (BCR). Generally, when the BCR exceeds 1, the improvement is deemed to be cost-beneficial. However, the models also allow the user to specify a BCR that is lower or higher as the criterion for choosing an improvement. A higher BCR threshold might be selected, for instance, when there is a limited budget for making improvements. The committee concluded that a BCR of 1 should be the basis for its nominal estimates of investment needs. As explained in Chapter 1, when Congress asked for estimates of the resources needed to restore and upgrade the Interstate System it did not specify a budget constraint. However, rec- ognizing that the funding available to invest in the system may be limited, the committee also computed the spending levels that would be required to make all improvements that meet a higher BCR threshold of 1.5. In each case, the models can be used to show how the investments would affect certain aspects of system condition, such as pavement smoothness and person-hours of delay. Note that the outcome of interest from investments is not necessarily a âstate of good repair.â While this term has become popular in transpor- tation asset management, what constitutes a âgoodâ condition remains ambiguous. Inasmuch as the pursuit of such a state implies that all system deficiencies should be corrected, the result can be overinvestment in work that does not produce net benefits. The presumption here is that policy makers seek investments that promise positive net benefits. Figure 5-5 summarizes the various components of the modeling ap- proach in a graphical format. The use of another tool to supplement the HERS and NBIAS models, the Pavement Health Track (PHT) tool, is ex- plained in the next section, which describes how the committee estimated pavement and bridge rehabilitation and reconstruction needs.
142 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM FIGURE 5-5 Schematic of application of HERS and NBIAS models for calculating Interstate Highway System investment needs for the next 20 years. Interstate Highway Interstate Bridges Traffic Growth 3 levels: â¢ Low VMT â¢ Nominal VMT â¢ High VMT HERS Benefit-cost ratio (BCR) investment screens: â¢ BCR â¥ 1.0 â¢ BCR â¥ 1.5 Capacity improvements in model â¢ Lane additions â¢ Lane and shoulder widening â¢ Operational improvements (e.g., ramp metering, incident management systems) Pavement improvements in model â¢ Resurfacing â¢ Partial reconstruction (i.e., surface layer) Adjustment factor from PHT/HERS comparison Calculates: â¢ Investment costs â¢ Delay Calculates: â¢ Investment costs â¢ IRI for resurfacing, partial reconstruction, and full-depth reconstruction Calculates: â¢ Total investment cost for bridges â¢ Bridge Health Index â¢ Percent of deck area structurally deficient Bridge improvements in model â¢ Bridge rehabilitation â¢ Bridge replacement NBIAS Preset investment level options: â¢ $2.8 B per year â¢ $3.8 B per year â¢ $4.8 B per year Calculates: â¢ Investment Costs â¢ International Roughness Index (IRI) only for resurfacing and partial reconstruction NBI data Inventory and condition of all bridges HPMS data Highway sample segments
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 143 ESTIMATING 20-YEAR PAVEMENT AND BRIDGE RENEWAL INVESTMENT NEEDS At a Glance â¢ Applying a strategy that invests in all cost-beneficial improve- ments, pavement investment needs average on the order of $27â $32 billion annually over the next 20 years (roughly double the current spending levels), based on assumed growth in VMT ranging from 0.75 to 2.0 percent per year. This investment level includes the cost of fully reconstructing Interstate pavements and their foundations. â¢ Modeling suggests that states are already devoting sufficient funds to continuing to maintain and improve Interstate bridges. Some- what higher annual investments (~25 percent) than are made today would lead to further improvements in the physical con- dition of these bridges by reducing structurally deficient deck area; however, this deficiency is generally considered to be a serviceability or ride quality issue rather than a safety concern. An investment level averaging $4 billion per yearâsimilar to what is being spent todayâis a reasonable approximation of the Interstate Systemâs bridge investment needs for the next 20 years. This section presents estimates of the investment required over the next 20 years to renew the Interstateâs pavements and bridges, which includes reducing the backlog of deferred investments, and to address forthcom- ing needs arising from the systemâs continued aging and future use. These estimates were derived largely from HERS and NBIAS, employing the as- sumptions discussed above. Pavement Investment Needs As discussed earlier, HERS, FHWAâs primary model for estimating national pavement investment needs, uses information about the current Interstate Highway Systemâs condition and performance from FHWAâs HPMS data- base (FHWA n.d.-d). When HERS is programmed with a specific rate of VMT growth, it computes the impact of the resulting traffic volumes and loadings on the systemâs physical condition and operating performance and generates a candidate set of standard improvements to highway width, pavement, and alignment, as well as additional lanes. The algorithms then calculate which improvements should be made according to the user- defined BCR.
144 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM As noted previously, a significant shortcoming of HERS for assess- ing pavement investment needs is that it does not consider all pavement conditions and types of improvements, partly because of limitations in the modelâs data source, HPMS. The condition of pavements is recorded in HPMS mainly according to a measure of ride quality, the International Roughness Index (IRI), which does not account for structural condition. Pavement improvement options in HERS are thus limited to surface treat- ments or partial reconstruction of top layers, which can be characterized only as rehabilitation or preservation work. As discussed in Chapter 3, the service life of pavements can be extended through such rehabilitation activity as resurfacing, but eventually the pave- ments and their foundations will deteriorate to a point where surface re- pairs are no longer effective, and the entire structure needs to be replaced from the subbase up. The timing of that eventuality depends on a number of factors, including design choices (e.g., pavement thickness, base depth), the quality of the original construction and materials, traffic loadings, and environmental factors (TRB 2007). One would expect, however, that states BOX 5-3 Estimated Benefits and Costs of Including Condition-Based, Full-Depth Pavement Reconstruction in Analysis of Interstate Investment Needs The present study used the Pavement Health Track (PHT) analysis tool, in addition to the Highway Economic Requirements System (HERS), to estimate Interstate highway reconstruction needs. Like HERS, PHT draws on pavement segment data from the national Highway Performance Management System (HPMS) database to screen for deficient segments, identifies feasible improvement options, selects an optimal option based on benefits and costs, and ultimately estimates costs of improvement. In contrast to HERS, however, PHT permits selection of multiple pavement condition metrics (e.g., fatigue cracking, rutting, faulting), including use of the International Roughness Index (IRI) to screen for deficiencies. The presence of fatigue crackingâa good indicator of full-depth cracking in all types of pave- mentsâwas used in this study as an indicator of structural inadequacy. A comparative analysis of projected improvement needs for a representative sample of more than 1,600 HPMS segments was performed using PHT together with HERS. The purpose of this analysis was to develop an adjustment factor that, when applied to the HERS output, would be indicative of the pavement improve- ments required (i.e., full-depth reconstruction or surface treatment). The comparative analysis was conducted for the following two scenarios: â¢ Scenario 1: For this scenario, a needs projection from PHT and HERS based on the IRI only was developed to provide a point of reference for comparing differences between key PHT and HERS outputs and making suitable calibration adjustments to PHT to ensure similar outcomes.
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 145 will find it necessary to increase spending on reconstruction of Interstate pavements over the next decade and beyond because much of the systemâs original foundation will not have been rebuilt. The inability of HERS to estimate full-depth reconstruction needs is problematic for estimating longer-term pavement investment needs. Thus to obtain a better understanding of the full-depth reconstruction that will be needed and its cost, the committee made use of FHWAâs PHT analysis tool. PHT, like HERS, uses HPMS data, but it screens more closely for signs of foundation deterioration by identifying pavement deficiencies based not only on surface smoothness measures (i.e., IRI) but also the observed pres- ence of fatigue cracking. PHT then determines that some pavement deficien- cies that would be identified by HERS as merely demanding rehabilitation should be treated in other ways, including full-depth reconstruction. The application of PHT to a sample of pavements in HPMS, as de- scribed in Box 5-3, allowed for the committee to develop an adjustment factor to apply to the HERS-derived estimates of pavement rehabilitation needs. In essence, the additional consideration of fatigue cracking suggests â¢ Scenario 2: For this scenario, only PHT runs were completed using both IRI and fatigue cracking for deficiency screening and an expanded set of treatment options typical of maintenance work ordering for pavements. The results of Scenario 1 indicate close agreement between key PHT and HERS outputs (average posttreatment IRI improvement and average benefit-cost ratio for the more than 1,600 HPMS segments analyzed), implying that no calibration of PHT outputs was required and providing a sound basis for investigating the combined circumstance of Scenario 2. The results of the Scenario 2 analysis show that the inclusion of full-depth cracking along with IRI enhances the ability to (1) identify pavement structural deficiencies and (2) select more life-cycle-optimized improvement options. The major conclusion is that when fatigue cracking is considered in maintenance decisions, the number of sections requiring planned maintenance actions and the associated costs increase significantly, whereas the number of sections requiring corrective maintenance, such as patching, decreases. In summary, compared with Scenario 1 (IRI only), the additional consideration of fatigue cracking in maintenance decisions results in an overall increase in fore- cast improvement costs by a factor of about 2.0 (i.e., 100 percent higher). Simulta- neously, benefits in terms of benefit-cost ratio (BCR) and extended pavement life are significantly higher than those accrued when IRI alone is used as a deficiency screening factor and criterion for postmaintenance restoration condition. Thus, use of this method makes it possible to obtain a first-order estimate of the increased costs and benefits that result when condition-based, full-depth reconstruction is considered as an option in the needs evaluation. A more robust analysis for all HPMS segments (beyond the scope of this study) is highly advisable to determine whether HERS is significantly underestimating pavement reconstruction needs on sections of the Interstate Highway System not previously reconstructed.
146 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM that the HERS results should be adjusted upward by a factor of 2. In the sections that follow, pavement investment needs are calculated first using HERS only, and second by applying the PHT-derived adjustment factor. Be- cause they include needed reconstruction work, the second set of estimates are considered to be more indicative of future investment needs. Rehabilitation-Only Estimates Using HERS Table 5-2 displays the HERS-computed annual investment that would be needed for pavement rehabilitation over the next 20 years under the high, nominal, and low VMT forecasts, in each case according to the two BCR investment criteria (BCR >1 or BCR >1.5). The table also shows the effect of applying these criteria on the share of Interstate pavements in poor con- dition, as measured by surface roughness (i.e., IRI). Rehabilitation spending in all cases would go up with increases in the rate of VMT growth. Invest- ing in all improvements having a BCR >1 would keep the share of pave- ments with poor surface conditions at the current 2 percent level at the end of the 20-year period. This strategy would require an annual investment of about $13â$17 billion depending on traffic growth rates. Applying a higher BCR of 1.5, as might be pursued under strict budget limitations, would reduce rehabilitation spending by about one-third, but pavement surface conditions would degrade significantly. Reconstruction and Rehabilitation Estimates Using HERS in Conjunction with PHT In recent decades, states have been designing and building Interstate pave- ment surfaces and foundations to achieve longer service lives (TRB 2007). TABLE 5-2 Annual 20-Year Investment for Alternative Pavement RehabilitationâOnly Investments Under Different Assumed Rates of Growth in Vehicle-Miles Traveled (VMT), Showing the Share of Pavements with Poor Surface Condition at the End of the 20-Year Period (in parentheses) Annual VMT Growth Rate Modest Nominal High Investment Criteria 0.75% 1.5% 2.0% BCR >1.0 $13.3B (4%) $14.4B (4%) $16.8B (4%) BCR >1.5 $9.0B (6%) $9.9B (7%) $10.5B (7%) NOTES: Results from analysis using the Highway Economic Requirements System (HERS). BCR = benefit-cost ratio.
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 147 However, the amount of mileage that has actually been impacted by these investments during highway reconstruction projects is not known. Whereas states are required to report to FHWA their total annual expenditures on Interstate reconstruction projects, they are not required to report the num- ber of miles or lane-miles involved. Because the amount of reconstructed Interstate mileage is not known, at least at the national level, it is difficult to know how much of the total system has a foundational footprint whose condition can be considered good. For the Interstate Systemâs first 20 to 40 years, however, relatively little was spent on reconstruction (as discussed in Chapter 3). Because so much of the Interstate System was built in the 1960s and early 1970s with 20-year design lives, it is reasonable to expect that a large share of the original pavement foundation remains in place and is due, or long overdue, for complete replacement. Table 5-3 presents the results of the combined HERS-PHT analysis under the same set of VMT growth rates and BCR investment criteria presented in Table 5-2. These results suggest that pavement investments over the next two decades will need to be approximately twice as high as those calculated by HERS of Interstate foundations that will need complete rebuilding rather than rehabilitation only. If nominal VMT growth (1.5 percent annually) is assumed and improvements having BCRs of 1 or higher are chosen, the annual investment in pavement is on the order of $29 bil- lion per year. Table 5-3 shows how these rehabilitation and reconstruction investment needs do not change much across the three different scenarios of growth in VMT. The reason the HERS-PHT estimates are significantly higher than the estimates derived from HERS alone is that reconstruction is much more expensive than simple rehabilitation. Case studies of Interstate pavement reconstruction projects undertaken for this study (see Appendix I) indicate TABLE 5-3 Annual 20-Year Investment Levels for Both Pavement Rehabilitation and Reconstruction Investment Under Different Assumed Rates of Growth in Vehicle-Miles Traveled (VMT), Showing the Resultant Share of Pavements with Poor Surface Condition at the End of the 20-Year Period (in parentheses) Annual VMT Growth Rate Modest Nominal High Investment Criteria 0.75% 1.5% 2% BCR >1.0 $26.6B (4%) $29.0B (4%) $31.6B (4%) BCR >1.5 $18.8B (6%) $19.8B (7%) $21.0B (7%) NOTES: Based on analysis conducted using the Highway Economic Requirements System (HERS) and Pavement Health Track (PHT). BCR = benefit-cost ratio.
148 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM that the average investment is about $2.8 million per lane-mile on a ru- ral Interstate and about $5 million per lane-mile on an urban Interstate (without adding any improvements beyond pavement reconstruction). The 20-year investment in reconstructed pavements, however, should lead to greater serviceability and lower resurfacing needs in decades beyond the 20-year period considered herein. Summary Assessment of Pavement Investment Needs The committee is reluctant to rely on the HERS-derived estimates of pave- ment investment needs because the Interstates are overdue for extensive pavement foundational work given their age. Although the combined PHT- HERS method yields a rough approximation of investment needs, the com- mittee believes it is more realistic in generating estimates of spending needs because it includes full reconstruction. Using this method, and applying a BCR threshold of 1, indicates that pavement investment needs will be on the order of $27â$32 billion annually over the next 20 years, based on VMT growth ranging from 0.75 to 2.0 percent per year. The above spending level represents a large increase over existing spending on Interstate pavements. As previously noted (see Figure 5-1), in 2014 states spent about $17 billion on Interstate pavement rehabilitation and reconstruction, representing nearly 67 percent of the $25 billion in total capital expenditures devoted to Interstates that year.5 Bridge Investment Needs The components of bridges, as typically described, are (1) the substructure (abutments and columns), (2) the superstructure (girders, trusses), and (3) the deck. Each of these components has its own service life and repair and maintenance requirements that depend on design and materials (e.g., prestressed concrete or steel) and exposure to weather and traffic. Well- maintained substructures and superstructures, especially those not exposed to chlorides from deicing-chemical runoff and saltwater splash and spray in marine environments, can last well over 50 yearsâpotentially more than 75 years in parts of southern and western states where these adverse conditions do not exist. Many concrete deck systems, by comparison, were designed to be serviceable for 30 to 50 years; however, their lives were of- ten shortened by exposure to heavy truck traffic and, in colder regions, by frequent and heavy applications of road salt (Azizinamini et al. 2014, 27). Many early Interstate bridge decks exposed to chlorides existing in marine environments and deicing chemicals failed quickly as the chlorides reached 5 This and subsequent references to Interstate capital spending by state departments of transportation (DOTs) in 2014 are from FHWA (2016b, Table SF-12A).
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 149 uncoated reinforcing steel within the deck, causing corrosion that induced concrete surface spalling and potholes. Decks account for the majority of state spending on bridges, mainly for repair and rehabilitation necessitated by damage from the effects of cor- rosion and heavy traffic loadings (Azizinamini et al. 2014, 15, 27). In the case of bridge substructures, chloride contamination of joints, bearings, and piers (due to runoff of salt-laden melt from decks) has also been a major cause of the need for maintenance and rehabilitation work. Over the past 30 or more years, damaged Interstate bridge decks and substructures have been rebuilt using epoxy-coated and zinc-coated reinforcement and stainless steel, which have substantially limited corrosion damage caused by deicing treatments and saltwater exposure. Bridge Investment Needs Estimated Using NBIAS NBIAS, FHWAâs bridge investment analysis tool, generates estimates of im- provement needs for Interstate bridges that, like those generated by HERS (which does not contain bridge information), are based on benefit-cost cal- culations. The NBIAS model, which is discussed in more detail in Appendix H, uses bridge condition data recorded from state inspections as reported in the National Bridge Inventory database. For each bridge element (e.g., deck, railings, girders, floor beams), the model considers the state of deterioration and whether there is a deficiency, identifies candidate actions for address- ing the deficiency (which can include maintenance, repair, rehabilitation, and strengthening), and computes the costs and benefits of taking those actions. If the improvements are not cost-beneficial, infeasible because of bridge design, or impracticable because of deteriorated structural condition, a bridge replacement âneedâ is generated based on state-reported structural condition values for new bridges. To make calculations, NBIAS uses a set of unit costs for various im- provement and preservation options; the model contains some 200 perfor- mance measures for assessing each option. The desired performance levels can be specified, as can constraints on spending and an acceptable BCR. Questions that NBIAS can address include, for example, what level of spending is required annually to maintain current bridge conditions over, say, the next 20 years and what user benefits might be achieved with a given set of improvement investments? To estimate Interstate bridge investment needs for the next 20 years, the committee applied NBIAS differently from HERS because VMT growth rates in the range of 0.75 to 2.0 percent per year were found to have only a small impact on the results. Rather than calculating all improvements that would meet or exceed a specified BCR and tabulating the resulting spending levels, different annual bridge spending levels were specified to test how they would impact the physical condition of Interstate bridges.
150 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM Two measures were used for bridge condition: (1) the percentage of total Interstate bridge deck surface area that would be rated as structurally defi- cient, and (2) a version of Californiaâs bridge âhealthâ index, which is based on an evaluation of the condition of 10 to 12 important bridge elements (from the substructure, superstructure, and deck), which was applied to the Interstate bridge inventory as a whole. In a sense, the entire inventory of Interstate bridges was treated as one structure encompassing all element quantities and condition distributions within the inventory.6 Three annual spending levelsâincluding the current level of $3.8 bil- lion per year as reported in the 2015 C&P report (FHWA 2016a, Exhibit 7-18)âwere used to determine impacts on bridge condition over the next 20 years. Table 5-4 presents the results of this analysis. They suggest that, unlike current pavement investments, current levels of Interstate bridge investment would lead to continued improvements in the structural conditions of bridge decks and in the overall health of the inventory. The percentage of structur- ally deficient deck area would be expected to decrease by several percentage points, and the overall health index of the systemâs bridges would remain es- sentially unchanged (increasing slightly from 92.8 to 93, where a high health index indicates better condition). Index values in the 90s suggest that bridges in the system are in generally good condition. A $1 billion increase in annual bridge spending would provide large additional reductions in the amount of deficient deck area but increase the health index only modestly. Summary Assessment of Bridge Investment Needs The NBIAS analysis suggests that states are already devoting sufficient funds to continuing to maintain and improve Interstate bridges, which 6 For a complete description of this index, see FHWA (2016c). TABLE 5-4 Estimated Annual Investments Needed to Improve Interstate Bridges Over the Next 20 Years Average Annual Investment Level Over 20 Years (2016 dollars) Percentage of Deck Area That Is Structurally Deficient Health Index Year 2016 Year 2036 Year 2016 Year 2036 $2.85B 11.6 13.5 92.8 90.1 $3.80B (current level) 11.6 7.6 92.8 93.0 $4.8B 11.6 3.5 92.8 94.9 NOTE: Analysis conducted using the National Bridge Investment Analysis System (NBIAS).
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 151 tends to be a high priority for safety reasons and because of the high value and use of Interstate bridges. Somewhat higher annual investments (~25 percent) would lead to further improvements in physical condition by re- ducing structurally deficient deck area; however, this deficiency is generally not considered to be a safety concern but a serviceability or ride quality issue. An investment level of $4 billion per year to further improve the condition of deck surfacesâsimilar to what is being spent todayâappears appropriate for bridge investment over the next 20 years. ESTIMATING 20-YEAR CAPACITY INVESTMENT NEEDS At a Glance â¢ Assuming an investment strategy that encompasses all cost-bene- ficial improvements, the annual 20-year investment for Interstate highway lane additions would be on the order of $13â$31 bil- lion, depending on realized vehicle-miles traveled (VMT) growth. These investment needs estimates are made with much less confi- dence than estimates for pavement and bridge work because they are highly dependent on assumptions about future travel demand, which is difficult to predict. â¢ Interchanges are an important source of bottlenecks and traffic delays; however, improvements to interchanges are not included in the existing analytical models. Similarly, no national inventory of Interstate interchanges or records of their condition exist, mak- ing it difficult to develop even rough estimates of future renewal requirements. â¢ Adding physical capacity is not the only means of alleviating congestion; ramp metering, incident management systems, hard shoulder running, managed lanes, adaptive speed limits, inte- grated corridor management, and weather management all can serve as means of accommodating increasing traffic volume. These improvements are estimated to require a $2 billion aver- age annual investment over the next 20 years. â¢ Toll-managed, truck-only, and reversible lanes cannot readily be examined using standard models; therefore, supplemental tech- niques were required for their evaluation herein. Of these three specifications, toll-managed lanes had the most effect in reducing congestionâby about one-third under most circumstances. Re- versible lanes require the least investment but are often difficult to implement. Truck-only lanes would be easiest to implement but would incur relatively high costs to produce relatively smaller congestion-reducing effect relative to toll-managed lanes.
152 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM Along with these substantial investments in pavement and bridge rehabilita- tion and reconstruction, additional investments will be required to expand and manage the Interstate Highway Systemâs capacity to handle future traffic. For reasons noted earlier, investments that will be required to ac- commodate this traffic demand are much more difficult to project because they are highly dependent on assumptions about future travel demand and its relationship to capacity. HERS can be a valuable tool for determining how different VMT growth rates affect system operating performance and capacity investment needs, but it has important limitations when consid- ering investments over long periods when myriad factors can change to affect travel behavior and as travelers respond to changes in capacity. Ac- cordingly, the estimates of capacity-related investment needs that follow are made with much less confidence than the estimates for pavement and bridge work, which are affected far less by changes in VMT. By using a range of historically informed VMT growth rates, the committee could, at best, make rough approximations of the magnitude of spending that might be needed for physical and operational capacity improvements over the next 20 years. In the sections that follow, various capacity investments are assessed us- ing HERS under alternative rates of VMT growth, starting with the option of adding more general-purpose lanes and making operational improve- ments (e.g., incident management). Consideration is then given to the use of toll-managed lanes, truck-only lanes, and reversible lanes. These latter options cannot readily be examined using HERS, and therefore required supplemental evaluation. Adding General-Purpose Lanes When VMT is assumed to grow, HERS considers a range of options for accommodating that growth in way that keeps congestion within defined parameters and calculates the BCRs for each option. Adding capacity by constructing a new lane is one option. Table 5-5 displays how adding lanes affects levels of Interstate traffic congestion using a BCR of 1 or higher. An annual expenditure of $22 billion over the next 20 years keeps congestion at levels comparable to those of today when a VMT growth rate of 1.5 percent per year is assumed. By comparison, a VMT growth rate of 2.0 percent per year requires expenditures of $31 billion annually over the next two decades, and even with that larger investment, congestion increases by nearly 25 percent over todayâs level. In this case, additional investments beyond $31 billion would not be cost-beneficial, mainly because of the dif- ficultly of acquiring the needed right-of-way in urban areas. The $22 billion per year that HERS estimates would be required for lane additions to keep delay at roughly todayâs levels (following a 20-year
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 153 period of 1.5 percent annual VMT growth) might be an acceptable invest- ment. However, adding physical capacity is not the only means of alleviating congestion, especially when delays are caused by nonrecurrent events such as traffic indents (e.g., crashes, disabled vehicles), road construction, and special events. The potential for accompanying investments in operational means to prevent or alleviate congestion is therefore considered below. It should be noted that the figures in Table 5-5 do not include invest- ments to upgrade the Interstate Highway Systemâs many interchanges. As previously noted, interchange improvements are not treated in HERSâa notable deficiency because interchanges are an important source of bot- tlenecks and traffic delay. Interchanges can be costly to reconfigure and reconstruct, creating operational challenges and consuming considerable right-of-way. While newer interchange designs that improve safety (e.g., âdiverging diamondsâ) have lessened the required right-of-way, renewal and modernization of Interstate interchanges will remain costly undertak- ings. Case studies indicate costs ranging from $80 million to more than $600 million per interchange, depending on the complexity of the inter- change and its context (see Appendix I). These projects can entail a wide range of activities, including reconfiguration, widening, structure replace- ment, realignment, and relocation. Inasmuch as these investments are not included in the HERS output, one could consider the investment levels in Table 5-5 to be lower bounds. TABLE 5-5 Annual 20-Year Investment Required for Interstate Highway Lane Additions to Accommodate Alternative Rates of Growth in Vehicle- Miles Traveled (VMT), Showing the Impact on Delay by the End of the 20-Year Period Annual VMT Growth Rate Investment Criteria 0.75% 1.5% 2.0% BCR â¥1 Annual Investment (billions) $13.2 $21.8 $31.3 Annual Peak-Period Delay in Person-Hours (millions) 1,800 2,500 3,100 BCR â¥1.5 Annual Investment (billions) $11.7 $13.4 $19.3 Annual Peak-Period Delay in Person-Hours (millions) 2,910 3,230 4,250 NOTE: Based on analysis using the Highway Economic Requirements System (HERS).
154 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM Adding Operational Improvements Options for accommodating various traffic volumes that are amenable to analysis using HERS are ramp metering, incident management systems, hard shoulder running, managed lanes, variable speed limits, integrated corridor management, and weather management. Figure 5-6 shows how investing in a combination of these operational improvements affects delay under different conditions of annual VMT growth. It assumes that all the investments in pavement improvements and lane additions discussed above that have a BCR of 1 or higher are accompanied by operational improve- ments (a $2 billion per year investment). The additional investment in operational mechanisms, representing a substantial increase over current spending on operational systems, leads to a roughly 10 percent reduction in delay. The effect of this $2 billion per year investments on delay is noted later in this chapter when 20-year investment needs are summarized. Using Toll-Managed, Truck-Only, and Reversible Lanes As noted earlier, HERS cannot be used to consider the full range of options for renewing and modernizing the Interstate Highway System. Excluded strategies include toll-managed lanes, truck-only lanes, and reversible lanes. While specific conditions under which each of these three strategies would be effective may differ, all would have their greatest applicability to urban FIGURE 5-6 Effects on traffic delay at the end of the 20-year period after adding $2 billion per year in operational improvements (to pavement and capacity projects). NOTE: Benefit-cost ratio (BCR) >1. With added operational improvementsWithout added operational improvements 0.75 1.5 2 Current peak-period person hours of delay = 100 0 20 40 60 80 100 120 140 160 180 VMT Growth Rate
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 155 corridors that are the locations of much of the countryâs traffic growth and suffer chronically high peak-period congestion. Tolling is increasingly being used to allocate scarce urban highway capacity and is typically implemented by adding toll-managed lanes, some- times called express toll lanes. Toll charges usually vary depending on time of day and/or traffic flow conditions and as such are a form of congestion pricing. State spending on toll-managed lanes is not reported separately to FHWA, but a survey found 41 deployments around the country, includ- ing 26 on Interstate highways.7 Reversible lanes are usually implemented as part of a larger corridor management strategy, and often involve the deployment of movable barriers on existing lanes to increase capacity in the direction of the heaviest traffic flow. Unlike toll-managed and revers- ible lanes, dedicated truck lanes do not exist on the Interstate Highway System. A number of proposals have been made for the deployment of tolled, dedicated truck lanes on Interstate corridors that have heavy freight volumes (e.g., the I-710 Freeway Separated Truck Lanes Proposal, Georgia I-75 Separated Truck Lane Proposal, and I-70 Corridor Dedicated Truck Lane Study). Some of these proposals envision restrictions on lane use to achieve benefits other than volume control, such as encouraging use of low- or zero-emission trucks. To estimate the effects of these three strategies in reducing congestion under the three alternative VMT growth rates considered herein, candidate Interstate segments were identified from HPMS data under the assumptions and rules detailed below. Toll-Managed Lanes An FHWA compilation of managed-lane projects indicates that adding a toll-managed lane costs about $4 million per mile and can be expected to enable a free-flowing capacity of 1,600 vehicles per hour per lane (vphpl) (FHWA n.d.-f). Using the highway segments in HPMS and assuming that a toll-managed lane would be deployed only in circumstances in which re- moving 1,600 vphpl from the general-purpose lanes and assigning that traf- fic to the toll-managed lane would still result in predicted congestion on the general-purpose lanes. The analysis reported herein assumes that congestion occurs when the ratio of peak volume to capacity on a lane is greater than or equal to 0.95. This rule is necessary because congestion must remain on the general-purpose lanes to continue to entice drivers to pay for the premium service. Thus, some sections that have volume-to-capacity ratios somewhat higher than 1.0 do not get a managed lane because not enough 7 See https://managedlanes.files.wordpress.com/2017/07/0-ml-database-green-yellow-blue- key-march-2017.pdf.
156 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM congestion remains in the general-purpose lanes after the premium lane has been added. Truck-Only Lanes Data from a recent NCHRP report indicate that adding a truck-only lane costs about $6.7 million per mile (Cambridge Systematics, Inc. 2010). The analysis reported herein using the highway segments in HPMS further assumes that truck lanes are deployed if the following condition is met: predicted truck volumes for the highway must exceed 10,000 vehicles per day, or the predicted percentage of trucks on the segment must exceed 25 percent when the volume-to-capacity ratio for the segment is between 0.9 and 1.4. Moreover, the new truck lane must have the potential to reduce the volume-to-capacity ratio (in the general-purpose lanes) to 0.9 or less (i.e., the new lane would reduce congestion meaningfully). Although not investigated in this analysis, the advent of autonomous and connected vehicle technologies could result in truck lanes with platooning, thereby increasing ca- pacity potential. How these vehicle technologies will develop and be deployed would clearly influence this alternative. Reversible Lanes Available information suggests that the cost per lane-mile of deploying a reversible lane is $1.7 million (Mobility Investment Priorities n.d.). In as- sessing this option (again using the highway segments in HPMS), it is as- sumed that a reversible lane will be deployed if no congestion occurs in the direction opposite to the direction of traffic on the reversable lane and that predicted speeds in the treated direction are increased to at least 45 mph. Results Table 5-6 presents the results of the analyses of these three congestion- reduction treatments. Of the three options, toll-managed lanes have the greatest impact, reducing congestion by about one-third on the corridors where they are deployed. Their overall effect is limited, however, by the fact that most congestion occurs in metropolitan areas, where right-of- way constraints and community concerns make the addition of new lanes cost-prohibitive. Although reversible lanes require the least investment, they have the least applicability and thus a limited effect on total traffic congestion. Truck-only lanes have the greatest applicability but relatively high costs, and produce less congestion reduction than toll-managed lanes. Because these three congestion-reduction treatments are generally sub- stitutes for one another and for some of the improvements addressed earlier,
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 157 the cost estimates in Table 5-7 cannot be added to the numbers in the sum- mary table in the following section. SUMMARY OF 20-YEAR INVESTMENT NEEDS Assuming Interstate traffic growth rates derived from forecasts of U.S. population and economic growth, FHWAâs HERS and NBIAS models in- dicate that a major additional commitment of resources will be needed to renew and modernize the Interstate Highway System over the next 20 years. These resources will be required in part to offset deferred investments that have the left portions of the systemâs foundation in a state of disrepair and in part to accommodate the systemâs continued aging and projected grow- ing traffic demands. TABLE 5-6 Congestion Impact and Cost of Alternative Highway Operations Treatments Deficient 2036 Interstate Lane-Miles Before Treatment* 0.75% Annual VMT Growth 29,057 Miles Added Reduced Congestion 20-Year Cost Truck-Only Lanes 7,000 16% $46.9B Toll-Managed Lanes 4,488 29% $18B Reversible Lanes 393 4% <$1B Deficient 2036 Interstate Lane- Miles Before Treatment* 1.5% Annual VMT Growth 49,155 Miles Added Reduced Congestion 20-Year Cost Truck-Only Lanes 9,479 15% $63.5B Toll-Managed Lanes 8,775 32% $39B Reversible Lanes 418 3% <$1B Deficient 2036 Interstate Lane- Miles Before Treatment* 2.0% Annual VMT Growth 66,549 Miles Added Reduced Congestion 20-Year Cost Truck-Only Lanes 11,481 12% $78B Toll-Managed Lanes 15,899 34% $64B Reversible Lanes 382 2% <$1B *Predicted volume-to-capacity ratio >1.
158 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM TABLE 5-7 Estimated Spending Needs for Interstate Highway Renewal and Modernization Over the Next 20 Years (minimum benefit-cost ratio [BCR] = 1.0) Average Annual Investment ($ billions) 2014 State and Federal Investmenta,b ($ billions) Annual Growth in Vehicle-Miles Traveled (VMT) Modest Nominal High 0.75% 1.5% 2% Resurfacing, partial and full reconstruction $16 $27 $29 $32 Bridge rehabilitation and replacement $4 $4 $4 $4 Rehabilitation and Reconstruction Subtotal $20 $31 $33 $36 Capacity additions $1 $13 $22 $31 Operations $0.4 $2 $2 $2 Capacity-Related Subtotal $1.4 $15 $24 $33 Condition and Performance After 20 Years If All Investments Are Made $21.4 $46 $57 $69 % miles with poor pavement surface 2% 4% 4% 4% Average annual peak- period delay (billions of person-hours) 2.4 1.8 2.5 3.1 Annual hours of peak-period delay per personc 11 9 12 15 a Data from FHWA (2016b, Table SF-12A). b Investments in 2014 also included $2.2 billion in new Interstate construction not included in this total. c The figures for person-hours of delay from the Highway Economic Requirements System (HERS) analysis are for the weekday peak periods in urbanized areas. To estimate the hours of delay per person, the total population in urban areas (220,482,000 as used in HERS) was adopted.
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 159 Table 5-7 summarizes estimates derived from the models used herein, in some cases supplemented by additional sources of information. The table includes only improvements that confer positive net benefits (BCR â¥1). De- pending on the rate of VMT growth realizedâfrom 0.75 to 2.0 percent per yearâthe projected investment required for a 20-year Interstate renewal and modernization program is on the order of $45â$70 billion annually, with the ânominalâ investment being $57 billion annually (VMT growth = 1.5 percent per year). While the bulk of this investment would be devoted to reconstruct- ing the systemâs pavement structures, substantial resources are also needed to enhance and align the systemâs capacity, especially if VMT growth is at the higher end of the range. In the latter instance, investments in enhancements in addition to widening will almost certainly be required, including operational investments that better allocate capacity, such as through congestion pricing of lanes in urban areas where land is both scarce and expensive. Expenditures of the magnitude displayed in Table 5-7 represent major increases over current Interstate investments of about $20â$25 billion an- nually. If the nominal VMT growth rate of 1.5 percent per year is assumed, investments over the coming 20 years will need to average $57 billion an- nuallyâmore than double the spending level of today. Even with these large expenditures, it is notable that some aspects of Interstate condition and performance would not improve, and perhaps deteriorate, relative to current conditions after 20 years. For example, if VMT grows 1.5 percent per year, even an average annual expenditure of $57 billion for pavement, bridge, and capacity-related improvements would result in levels of traffic delay comparable to today. To achieve much lower levels of delay (e.g., 75 percent of current peak-period hours of delay), as shown in Figure 5-7, would also require much higher levels of spending. Those much higher spending levels would not be justified on a benefit-cost basis, as calculated by the models. Figure 5-8 shows how increasingly higher investment totals would af- fect pavement surface condition and traffic delay depending on assumed rates of growth in VMT. In the case of nominal VMT growth (1.5 percent per year), average annual investments would need to be three times higher than they are today (>$75 million per year) to keep pavement surface condi- tions comparable to existing conditions but to reduce delay by 25 percent from current levels. These expenditure requirements would need to increase by another large increment if VMT is assumed to grow at annual rate of 2 percent. Annual spending would need to be double existing levels even if VMT is assumed to grow at the more modest pace of 0.75 percent annu- ally. Again, these much higher spending levels are not economically justified according to the models. All of these projections are, of course, based on models that have short- comings acknowledged herein. It is the committeeâs judgment, however,
160 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM FIGURE 5-7 Average investment (federal and state) per year to achieve specified peak-period delay levels in 20 years relative to 2016 (assuming 1.5 percent annual growth in vehicle-miles traveled [VMT]). 0 1 2 3 4 5 6 7 8 9 20 30 40 50 60 70 80 90 100 An nu al P ea k- Pe rio d De la y (b ill io ns o f p er so n- ho ur s) Average Annual Investment ($ billion) from 2016 to 2036 Low Projection, 0.75% Nominal Projection, 1.5% High Projection, 2% 4 6 5 12 8 5 4 2 9 6 4 2 5 4 4 4 3 2 4 Annual VMT Growth Percentage of Miles of Pavement in Poor Condition FIGURE 5-8 Modeled impact of annual Interstate investments on delay and pave- ment surface condition after 20 years assuming different rates of annual VMT growth. NOTE: Investments are in constant 2016 dollars. 133Bi llio ns o f 2 01 6 do lla rs p er y ea r 100 90 75 2016 spending Percentage of 2016 delay 0 20 40 60 80 100
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 161 that the predicted totals are more likely to underestimate than overestimate actual investment needs. This judgment is based on the fact that, irrespec- tive of the specific rates of growth in traffic over the next two decades, the existing system has a large backlog of work that will require substantial investment in itself. Although proven durable, the Interstate Systemâs road- way foundation will eventually become unserviceable, and much of it is already more than 50 years old. It must also be recognized that the nationâs population is increasing, further concentrating in large metropolitan areas where the most congested highways exist. The need to invest in both the foundation and the traffic capacity of the Interstate System will fall disproportionately on urban por- tions of the system, where construction and reconstruction costs are the highest, and perhaps underestimated by the models. SUPPLEMENTAL INVESTMENTS IN RESILIENCE AND RIGHTSIZING The above estimates do not include consideration of three important needs, discussed in Chapters 3 and 4, that are likely to have a profound impact on the Interstate Highway System, particularly beyond the 20-year period that is the focus of this chapter. The first is to make the system more resil- ient to the effects of climate change. The second is to rightsize the systemâs footprint in response to a geographically shifting population and economy, including community concerns about the intrusiveness of some Interstate highways. And the third is to adapt to rapidly advancing technologies, including an all-electric vehicle fleet, fully automated vehicles, and the ex- panding use of drones. Although federal-aid funds for planning and research can be used by states and metropolitan areas to conduct vulnerability assessments and ana- lyze adaptation options, there is no special federal funding program for resil- ience (FHWA n.d.-b). FHWA has reported that more than $350 million was expended on highways in the Northeast that were damaged during Hurricane Sandy in 2013 (FHWA n.d.-e). Nonetheless, the investments for highway re- pairs are only a portion of the costs resulting from the Interstate Systemâs lack of resilience: extreme weather events also incur significant economic costs due to highway closures and their impact on commerce. Should the effects of climate change become even more prominent and problematic over the next two decades, additional expenditures will be needed to make the Interstates more resilient. Importantly, there may be many cost-effective steps that could be taken in the years just ahead to improve Interstate resilience, particularly considering the long expected lifetimes of highway assets. With regard to rightsizing, FHWA has established criteria for addi- tions and withdrawals of Interstate Highway System routes (see Box 5-4).
162 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM While these criteria are intended to ensure connectivity and prevent dupli- cation, they distinguish among investments that would serve the national interests, as opposed to serving mainly state or local interests. The criteria include grounds for replacement of Interstate highway segments (FHWA n.d.-c), including replacement of what some view as âoverbuiltâ urban Interstate spurs that terminate in downtown areas but might better serve community interests if downgraded to allow for more local-use access, or even removed. As of 2016, FHWA had received inquiries from 12 states on how to withdraw Interstate segments (involving 17 Interstate segments). The agency has approved three such requests in recent years (FHWA n.d.- g). In 2008, for example, the District DOT (DDOT), in Washington, DC, requested the withdrawal of a segment of I-295 that was part of a longer BOX 5-4 Federal Criteria for Interstate Route Additions and Withdrawals In addition to the Interstate routes originally authorized, until 1978 Congress ap- proved the addition of new corridor-miles and expanded eligibility for Interstates Construction (IC) funds. The Surface Transportation Assistance Act of 1978, how- ever, prohibited the use of IC funds for any new miles designated after passage of the act. A total of 42,795 miles had been designated for development with IC funds before this measure was enacted. Under current law, FHWA, at the request of a state or states, can designate sections of the National Highway System as new segments of the Interstate Highway System, although doing so does not authorize additional funding. The guidance criteria for evaluating requests for new Interstate routes are as follows (CFR Title 23 Â§ 470.111âInterstate System Procedures. Appendix A). 1. The proposed route should be of sufficient length to serve long-distance Interstate travel, such as connecting routes between principal metropolitan cities or industrial centers important to national defense and economic development. 2. The proposed route should not duplicate other Interstate routes. It should serve Interstate traffic movement not provided by another Interstate route. 3. The proposed route should directly serve major highway traffic generators. The term âmajor highway traffic generatorâ means either an urbanized area with a population of more than 100,000 or a similar major concen- trated land use activity that produces and attracts long-distance Interstate and statewide travel of persons and goods. Typical examples of similar major concentrated land use activities would include a principal indus- trial complex, government center, military installation, or transportation terminal. 4. The proposed route should connect to the Interstate System at each end, with the exception of Interstate routes that connect with continental routes at an international border, or terminate in a âmajor highway traffic genera- torâ that is not served by another Interstate route. In the latter case, the
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 163 route that was never completed. In its place, DDOT planned to convert the withdrawn Interstate segment to an urban boulevard. Primary candidates for upgrades to the Interstate System are highways in the National Highway System (NHS) that are currently functioning in a manner similar to the Interstates and that can be expected to experience heavy demand over the next 20 years. To estimate how much mileage would qualify, it is assumed that VMT grows at the nominal projected rate (1.5 percent per year) over all NHS routes and that 2016 HPMS data can be used to estimate the impacts on traffic volumes. When traffic reaches a volume-to-capacity ratio greater than or equal to 0.9 and an annual average daily traffic (AADT) of 30,000 or more on a given highway segment, it is assumed that an investment of $10 million per mile (based on experience terminus of the Interstate route should connect to routes of the National Highway System that will adequately handle the traffic. The proposed route also must be functionally classified as a principal arterial and be a part of the National Highway System. 5. The proposed route must meet all the current geometric and safety stan- dards criteria as set forth in 23 CFR part 625 for highways on the Interstate System, or a formal agreement to construct the route to such standards within 25 years must be executed between the State(s) and the Federal Highway Administration. Any proposed exceptions to the standards shall be approved at the time of designation. 6. A route being proposed for designation under 23 U.S.C. 103(c)(4)(B) must have an approved final environmental document (including, if required, a 49 U.S.C. 303(c) [Section 4(f)] approval) covering the route, and project action must be ready to proceed with design at the time of designation. Routes constructed to Interstate standards are not necessarily logical ad- ditions to the Interstate System unless they clearly meet all of the above criteria. Withdrawal or removal of Interstate highways is also allowed (FHWA n.d.-c). Reasons identified in the criteria for withdrawal include urban Interstate spurs that terminate in downtown areas and might better satisfy local transportation and livabil- ity needs if they were downgraded to urban routes. Only the transportation agency in the state in which the highway is located can request the withdrawal of Interstate sections/corridors, and such withdrawals must be formally requested to FHWA. Title 23 of the Code of Federal Regulations also regulates the use and disposition of property previously acquired by states for Interstate segments. It addresses the process by which and extent to which a payback to the federal government is re- quired for property acquired by states with the participation of federal-aid highway funds (23 CFR 480*). *Code of Federal Regulations, Title 23, Part 480, https://www.gpo.gov/fdsys/pkg/CFR-1998- title23-vol1/xml/CFR-1998-title23-vol1-part480.xml.
164 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM with I-69 as discussed in Chapter 3) would be required to convert the highway to an Interstate. About 150 rural NHS miles and more than 3,200 urban NHS miles would qualify under these criteria, as shown in Table 5-9. This added mileage would require an investment of about $32 billion. (Obviously, some of these miles would not be candidates for conversion to Interstates because they involve only short segments as opposed to full routes.) SUMMARY The committee used standard FHWA models for estimating highway and bridge investment needs as the primary basis for estimating investment levels required to renew and modernize the Interstate Highway System over the next 20 years, considering a range of rates of traffic growth. Whether a potential investment is viewed as justified ultimately depends on the highway condition and performance outcomes considered acceptable. While such outcomes are largely subjective, the estimates developed in this TABLE 5-9 Candidate NHS Mileage for Upgrade to Interstate Status by State Based Only on Predicted Levels of Congestion with an Annual VMT Growth Rate of 1.5 Percent per Year Center-Line Mileage Center-Line Mileage Rural Urban Rural Urban Alabama 8.8 Missouri 21.2 Arizona 66.1 Nebraska 6.6 Arkansas 14.8 Nevada 27.0 California 64.2 746.1 New Hampshire 1.4 33.2 Colorado 1.7 55.3 New Jersey 5.9 166.9 Connecticut 0.7 100.6 New York 224.2 Delaware 11.0 13.6 North Carolina 52.8 District of Columbia 1.6 Ohio 58.7 Florida 13.1 263.6 Oklahoma 39.4 Georgia 44.9 Oregon 33.2 Hawaii 0.6 Pennsylvania 5.6 72.6 Illinois 15.9 Rhode Island 7.6 Indiana 0.3 South Carolina 0.5 Kansas 23.0 Tennessee 47.2 Kentucky 11.4 Texas 496.8 Louisiana 1.6 Utah 0.6 6.3 Maryland 110.6 Virginia 8.7 61.5 Massachusetts 2.1 84.6 Washington 1.4 44.8 Michigan 33.9 130.0 Wisconsin 35.9 Minnesota 104.4 Mississippi 0.9 All States 150.3 3,235.1
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 165 chapter were derived from modeled benefit-cost calculationsâthe approach recommended by Congress in requesting this study. The following estimates are intended to provide general guidance regarding the magnitude of invest- ments required over the next 20 years under a moderate investment strategy that encompasses all cost-beneficial improvements. Total investment needs. Using the methods described in this chapter, the committee derived a nominal estimate of $57 billion total average annual expenditures (with a range of $45â$70 billion, depending on the choices to be made and uncertainties). Pavement investment needs. Investment in pavements is estimated to be on the order of $27â$32 billion annually over the next 20 years, based on assumed rates of growth in VMT ranging from 0.75 to 2.0 percent per year. This figure includes the cost of fully reconstructing Interstate pave- ments and their foundations. Bridge investment needs. Modeling suggests that states are currently devoting sufficient funds to maintaining and improving Interstate bridges. Somewhat higher annual investments (~25 percent) would lead to further improvements in physical condition by reducing deficient deck area; how- ever, this deficiency is generally considered a serviceability or ride quality issue, not a safety concern. An investment level of $4 billion per yearâ similar to what is being spent todayâis a reasonable representation of the Interstate Systemâs bridge investment needs for the next 20 years. Investment in lane additions. Under the assumed moderate investment strategy, the annual 20-year investment required for Interstate highway lane additions is nominally $22 billion, with a potential range of $13â$31 bil- lion, depending on the rate of traffic growth. These investments would result in annual peak-period delays of approximately 1,800â3,100 million person-hours per year, also depending on the rate of traffic growth. Investment in interchanges. Interchanges are an important source of bottlenecks and traffic delay; improvements to interchanges, however, can- not be modeled using current capabilities. No national inventory of Inter- state interchanges or records of their condition exist, thus making it difficult to develop even rough estimates of future renewal requirements. Investment in operational measures. Deploying means other than physi- cal additions to the Interstate System, such as ramp metering, incident management, hard shoulder running, managed lanes, variable speed limits, integrated corridor management, and weather adaption, is estimated to require a $2 billion average annual investment. Supplemental investments. Finally, it is important to note that the nom- inal estimate of $57 billion total average annual expenditures (with a range of $45â$70 billion, depending on the choices to be made and uncertainties) is incomplete because it does not include the investments required in sev- eral areas that cannot be responsibly estimated at this point but are certain
166 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM to require billions, perhaps many billions, in additional spending. These investments would be necessary to reconfigure and reconstruct many of the systemâs roughly 15,000 interchanges (Gehr 2010, 9), make the system more resilient to the effects of climate change, expand and allocate more efficiently system capacity in and around metropolitan areas, and begin to adapt to major technological changes affecting both vehicles and highways. REFERENCES Abbreviations FHWA Federal Highway Administration TRB Transportation Research Board Azizinamini, A., E. H. Power, G. F. Myers, and H. C. Ozyildirim. 2014. Bridges for Service Life Beyond 100 Years: Innovative Systems, Subsystems, and Components. SHR2 Report S2-R19A-RW-1. Transportation Research Board, Washington, D.C. https://www.nap.edu/ catalog/22479/bridges-for-service-life-beyond-100-years-innovative-systems-subsystems- and-components. Cambridge Systematics, Inc. 2010. Separation of VehiclesâCMV-Only Lanes. NCHRP Report 649. Transportation Research Board, Washington, D.C. http://infrastructureaustralia. gov.au/policy-publications/publications/files/Separation_of_Vehicles_CMV_Only_Lanes_ Joint_Report_National_Cooperative_Highway_and_Freight_Research_Program.pdf. FHWA. 1999. Highway Statistics 1998: State Highway Agency Capital Outlayâ1998 for Arterial Systems in Rural Areas Classified by Improvement Types. Table SF-12A. https:// www.fhwa.dot.gov/policyinformation/statistics/1998/pdf/sf12a.pdf. FHWA. 2000. Highway Statistics 1999: State Highway Agency Capital Outlayâ1999 for Arterial Systems in Rural Areas Classified by Improvement Types. Table SF-12A. https:// www.fhwa.dot.gov/ohim/hs99/tables/sf12a.pdf. FHWA. 2001. Highway Statistics 2000: State Highway Agency Capital Outlayâ2000 for Arterial Systems in Rural Areas Classified by Improvement Types. Table SF-12A. https:// www.fhwa.dot.gov/ohim/hs00/pdf/sf12a.pdf. FHWA. 2002. Highway Statistics 2001: State Highway Agency Capital Outlayâ2001 for Arterial Systems in Rural Areas Classified by Improvement Types. Table SF-12A. https:// www.fhwa.dot.gov/ohim/hs01/pdf/sf12a.pdf. FHWA. 2003. Highway Statistics 2002: State Highway Agency Capital Outlayâ2002 for Arterial Systems in Rural Areas Classified by Improvement Types. Table SF-12A. https:// www.fhwa.dot.gov/policy/ohim/hs02/pdf/sf12a.pdf. FHWA. 2004. Highway Statistics 2003: State Highway Agency Capital Outlayâ2003 for Arterial Systems in Rural Areas Classified by Improvement Types. Table SF-12A. https:// www.fhwa.dot.gov/policy/ohim/hs03/pdf/sf12a.pdf. FHWA. 2005. Highway Statistics 2004: State Highway Agency Capital Outlayâ2004 for Arterial Systems in Rural Areas Classified by Improvement Types. Table SF-12A. https:// www.fhwa.dot.gov/policy/ohim/hs04/pdf/sf12a.pdf. FHWA. 2006. Highway Statistics 2005: State Highway Agency Capital Outlayâ2005 for Arterial Systems in Rural Areas Classified by Improvement Types. Table SF-12A. https:// www.fhwa.dot.gov/policy/ohim/hs05/pdf/sf12a.pdf.
SYSTEM INVESTMENT NEEDS: A 20-YEAR HORIZON 167 FHWA. 2007. Highway Statistics 2006: State Highway Agency Capital Outlayâ2006 for Arterial Systems in Rural Areas Classified by Improvement Types. Table SF-12A. https:// www.fhwa.dot.gov/policy/ohim/hs06/pdf/sf12a.pdf. FHWA. 2008. Highway Statistics 2007: State Highway Agency Capital Outlayâ2007 for Arterial Systems in Rural Areas Classified by Improvement Types. Table SF-12A. https:// www.fhwa.dot.gov/policyinformation/statistics/2007/sf12a.cfm. FHWA. 2009. Highway Statistics 2008: State Highway Agency Capital Outlayâ2008 for Arterial Systems in Rural Areas Classified by Improvement Types. Table SF-12A. https:// www.fhwa.dot.gov/policyinformation/statistics/2008/sf12a.cfm. FHWA. 2012a. Highway Statistics 2009: State Highway Agency Capital Outlayâ2009 for Arterial Systems in Rural Areas Classified by Improvement Types. Table SF-12A. https:// www.fhwa.dot.gov/policyinformation/statistics/2009/sf12a.cfm. FHWA. 2012b. Highway Statistics 2010: State Highway Agency Capital Outlayâ2010 for Arterial Systems in Rural Areas Classified by Improvement Types. Table SF-12A. https:// www.fhwa.dot.gov/policyinformation/statistics/2010/sf12a.cfm. FHWA. 2014. Highway Statistics 2012: State Highway Agency Capital Outlayâ2012 for Arterial Systems in Rural Areas Classified by Improvement Types. Table SF-12A. https:// www.fhwa.dot.gov/policyinformation/statistics/2012/pdf/sf12a.pdf. FHWA. 2015. Highway Statistics 2013: State Highway Agency Capital Outlayâ2013 for Arterial Systems in Rural Areas Classified by Improvement Types. Table SF-12A. https:// www.fhwa.dot.gov/policyinformation/statistics/2013/sf12a.cfm. FHWA. 2016a. 2015 Status of the Nationâs Highways, Bridges, and Transit: Conditions & Performance. https://www.fhwa.dot.gov/policy/2015cpr. FHWA. 2016b. Highway Statistics 2014: State Highway Agency Capital Outlayâ2014 for Arterial Systems in Rural Areas Classified by Improvement Types. Table SF-12A. https:// www.fhwa.dot.gov/policyinformation/statistics/2014/sf12a.cfm. FHWA. 2016c. Synthesis of National and International Methodologies Used for Bridge Health Indices. FHWA-HRT-15-081. https://www.fhwa.dot.gov/publications/research/ infrastructure/structures/bridge/15081/15081.pdf. FHWA. 2017. Highway Statistics 2016: Vehicle-Miles of Travel, by Functional System, 1980â 2016. Table VM-202. https://www.fhwa.dot.gov/policyinformation/statistics/2016/pdf/ vm202.pdf. FHWA. n.d.-a. A Guide to Reporting Highway Statistics. Chapter 12. https://www.fhwa.dot. gov/policyinformation/hss/guide/index.cfm. FHWA. n.d.-b. FAQ: Emergency Relief Program and Resilience. https://www.fhwa.dot.gov/ environment/sustainability/resilience/publications/er_faq/index.cfm. FHWA. n.d.-c. Guidance on the Withdrawal or De-designation of Segments of the Inter- state Highway System. https://www.fhwa.dot.gov/planning/national_highway_system/ interstate_highway_system/withdrawalqa.cfm. FHWA. n.d.-d. Highway Performance Monitoring System (HPMS). https://www.fhwa.dot.gov/ policyinformation/hpms.cfm. FHWA. n.d.-e. Post Hurricane Sandy Transportation Resilience Study in NY, NJ, and CT. https://www.fhwa.dot.gov/environment/sustainability/resilience/publications/hurricane_ sandy/page02.cfm#toc494879274. FHWA. n.d.-f. Priced Managed Lane Guide Appendix: Priced Managed Lane Profiles I-680 SB Express Lane. https://ops.fhwa.dot.gov/publications/fhwahop13007/app.htm. FHWA. n.d.-g. Withdrawal of Segments from the Interstate SystemâMarch 10, 2016 Webinar Recording. https://www.fhwa.dot.gov/planning/national_highway_system/ interstate_highway_system.
168 NATIONAL COMMITMENT TO THE INTERSTATE HIGHWAY SYSTEM Gehr, D. 2010. Unlock Gridlock. AASHTO, Washington, D.C. https://books.google.com/bo oks?id=Meh6Mk2xtIAC&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v= onepage&q&f=false. Miller, D., S. Binder, H. Louch, K. Ahern, H. Kassoff, and S. Lockwood. 2013. Specifica- tions for a National Study of the Future 3R, 4R, and Capacity Needs of the Interstate System. NCHRP Project 20-24(79). http://onlinepubs.trb.org/onlinepubs/nchrp/docs/ NCHRP20-24(79)_FR.pdf. Mobility Investment Priorities. n.d. Reversible Traffic Lanes. https://mobility.tamu.edu/mip/ strategies-pdfs/traffic-management/technical-summary/Reversible-Traffic-Lanes-4-Pg.pdf. TRB. 2007. Pavement Lessons Learned from the AASHO Road Test and Performance of the Interstate Highway System. Transportation Research Circular E-C118. Transportation Research Board, Washington, D.C. http://onlinepubs.trb.org/onlinepubs/circulars/ec118. pdf. TRB. unpublished. Final Report: Developing a Process to Assess Potentially Underestimated Interstate Highway Reconstruction Needs in the U.S. DOT Conditions and Performance and AASHTOâs Bottom Line Reports (A Scoping Study). NCHRP 20-24(52) Task 14. National Academies of Sciences, Engineering, and Medicine, Washington, D.C. TRB Transportation Economics Committee. n.d. Transportation Benefit-Cost Analysis: HERS- ST. http://bca.transportationeconomics.org/models/hers-st.