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135 APPENDIX B Highway Congestion and the Aviation System From the original project statement and request for pro- B.1 Highway Demand and Capacity posal, the research effort has been concerned with the poten- in the East Coast Mega-region tial impacts on aviation capacity from possible changes in competing or complementary modes. The research team's The coastal mega-regions are served by highway systems work has included, therefore, a review of the extent to which that include major interstate highways, state highways, toll there might be some additional capacity in the roadway roads, and toll bridges. As with most transportation facilities, networks in the two mega-regions that could in some way the performance of these systems is heavily affected by di- influence alternative futures for the accommodation of avi- urnal, daily, weekly, and seasonal fluctuations in demand. ation demand. This Appendix to the main document sum- Because of this, characterizations of system capacity are gen- marizes the results of the research team's review of demand erally referenced against some time period. The traditional and capacity of highways as undertaken as an input to the traffic engineering approach is to design a facility so that it analysis of the capacity needs of the U.S. aviation/airport operates without significant congestion during the so-called system. "design hour" that, in many regions, is defined as the 30th high- Section B.1 reviews what is known about the bottlenecks est hourly traffic flow over the course of a year. However, in and sources of congestion in the East Coast Mega-region; it the coastal mega-regions, most of the major highway facili- reviews highway demands and capacities at the region's key ties operate with traffic flows that are well above levels that locations. Areas where demand significantly outweighs capac- would maintain that standard. ity are documented for the East Coast. By way of example, The I-95 Corridor Coalition has made a major commit- demands and supplies on a key link across the Hudson River ment to providing improved understanding of the long- in the NYC area are reviewed to show the difficulty of predict- distance trip, including the trips by vehicles on the roadway ing what major improvements to the total network can be system. The Coalition is an alliance of transportation agen- expected. cies, toll authorities, and related organizations encompass- Section B.2 includes a review of known congested seg- ing the multistate East Coast Mega-region. The Coalition ments of the California highway system--in particular, those provides a forum for key decision- and policymakers to that serve as gateways for northsouth traffic between the address transportation management and operations issues two West Coast Mega-regions. In California, a future high- of common interest, including current and future perfor- way network was developed as part of the HSR forecasting mance of the highway system. As one of its projects, the process, and the impact of that future highway network on Coalition has been developing a new tool to identify major interregional travel was calculated. The California analysis transportation system bottlenecks and potential multimodal shows that, even with the creation of an aggressive future approaches to address those bottlenecks. The tool, labeled highway network, the fundamental long-distance intercity ICAT (Integrated Corridor Analysis Tool), includes a coded travel times do not improve. highway network for the I-95 region with traffic flow and Section B. 3 concludes with the finding that the only way capacity data. in which future highways could provide continuous capacity ICAT was used by the Coalition to identify major facilities not available today would be with the creation of continuous that are subject to significant congestion and that, in effect, intercity-managed lanes to support new kinds of intercity serve as bottlenecks in the corridor. A capacity index was cal- bus services. culated as the annual average daily traffic volume divided by
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136 the hourly traffic capacity of the facility. This can be inter- Dust Network" data (B-2). Since 2006, INRIX has acquired preted as the number of hours of full capacity flow that are "GPS-enabled probe vehicle reports from commercial fleet represented by the average daily traffic volumes. The maxi- vehicles including taxis, airport shuttles, service delivery mum possible value for this index would be 24, but that would vans, long haul trucks and cellular probe data." The I-95 imply that traffic flows equal capacity for all 24 hours of an Corridor Coalition has a contract to INRIX to provide the average day. As traffic flows in practice vary significantly across Coalition access to both real-time and historical performance the day and, in particular, are very much lower at night, index data for the highways and arterials in the region. This dataset values above 10.0 are generally associated with significant con- will provide detailed information about the performance of gestion levels on "average" days and for more than the typical the highway network over time, and INRIX has used the data few hours of peak congestion. to calculate its own congestion index. That index is calculated as the number of hours during which traffic moves at a speed lower than 50% of the free-flow speed per week divided by the B.1.1 East Coast Highways with High average speed during those hours. Volume-to-Capacity Relationships It is not surprising that the coastal mega-regions high- Table B.1 lists 20 of the East Coast Mega-region highways ways are prominently featured in INRIX's list of the worst with the highest index values as calculated by ICAT. The full 100 bottlenecks in the United States, based on their index. Of ICAT-generated lists includes close to 100 East Coast Mega- the top 100, over 70% are in the coastal mega-regions, includ- region highway sections with index values above 10.0, so the ing all of the top 5. Table B.2 lists the East Coast Mega-region table should be viewed as indicative of the sections that are highways that appear on the INRIX Top 100 list, along with the most congested. I-95, which is the major highway serving their performance statistics. the corridor, is heavily represented both in the truncated list As shown in Table B.2, the top-ranked (worst) from this above and in the longer ICAT list. This indicates that the cor- list, the Cross-Bronx westbound, is congested, on average, for ridor is currently operating at its effective capacity for much 94 hours per week at an average speed of less than 10 mph. of the day and for much of its length. Assuming that the congested hours are spread across week- A more direct measurement of the current highway oper- days and weekends evenly, this amounts to over 13 hours of ating conditions is provided by the detailed INRIX "Smart congested conditions per day. Table B.1. ICAT Top 20 East Coast bottlenecks (B-1). Location Route Daily Traffic No. of Lanes Capacity Index Queens, NY I-678 178,434 4 20.4 Delaware, PA I-95 173,664 4 19.9 Norfolk, VA I-264 198,317 5 18.1 Brooklyn, NY I-278 156,632 4 17.9 Prince Georges, MD I-95 191,610 5 17.5 Baltimore, MD I-695 227,133 6 17.3 Fairfax, VA I-95 146,114 4 16.7 Philadelphia, PA I-76 139,692 4 15.9 Hartford, CT I-84 137,500 4 15.8 Long Island, NY I-495 206,379 6 15.7 New Castle, DE I-95 130,459 4 15.1 Baltimore, MD I-83 192,790 6 15.0 Staten Island, NY I-278 194,734 6 14.8 Bronx, NY I-95 130,012 4 14.8 Montgomery, MD I-270 126,781 4 14.5 Bergen, NJ I-95 312,592 10 14.3 New Haven, CT I-91 90,800 3 14.0 Philadelphia, PA I-95 178,945 6 13.7 Delaware, PA I-476 117,378 4 13.4 Fairfax, VA I-66 174,275 6 13.3
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137 Table B.2. INRIX Top 100 U.S. bottlenecks--East Coast highways (B-2). Rank Road County Hours Congested Avg. When Congested 1 Cross Bronx Expy WB Bronx 94 9.8 2 Cross Bronx Expy WB Bronx 92 9.5 4 Cross Bronx Expy WB Bronx 81 11.1 5 Cross Bronx Expy WB Bronx 95 11.3 5 Harlem River Dr SB New York 65 8.4 7 I-95 NB Bergen 65 7.2 8 Van Wyck Expy NB Queens 81 12.3 15 Harlem River Dr. SB New York 70 11.1 17 Van Wyck Expy NB Queens 75 14.7 19 Lincoln Tunnel EB Hudson 61 6.9 22 Hwy 495 EB Hudson 42 7.2 23 Staten Island Expy EB Richmond 64 12.4 24 I-95 NB Bergen 55 10.4 25 George WA Bridge Bergen 62 8.0 31 Major Deegan Expy NB Bronx 52 10.4 34 Hwy 495 EB Hudson 48 9.2 42 Van Wyck Expy NB Queens 77 13.7 43 Cross Bronx Expy WB Bronx 68 14.5 45 Staten Island Expy EB Richmond 57 13.7 47 Alexander Hamilton Bridge EB Bronx 63 12.7 51 I-91 SB New Haven 68 15.4 59 Harlem River Dr SB New York 45 11.1 61 Van Wyck Expy NB Queens 58 13.3 67 Van Wyck Expy NB Queens 58 13.1 70 Brooklyn Queens Expy SB Kings 58 12.1 74 George WA Bridge New York 68 14.4 75 Brooklyn Queens Expy SB Kings 51 11.7 78 Major Deegan Expy NB Bronx 50 12.5 79 FDR Dr SB New York 67 13.1 80 Long Island Expy EB Queens 42 11.8 84 Henry Shirley Memorial Hwy NB Arlington 43 10.5 90 Cross Bronx Expy WB Bronx 55 14.8 91 Van Wyck Expy NB Queens 75 15.8 97 Cross Bronx Expy WB Bronx 65 15.7 B.1.2 An Example of Road Capacity rently under environmental analysis, and data about several Constraints, Current and Future: alternative futures are readily available to the public.) A Hudson River Crossing Present capacity, present demand. The Tappan Zee Tables B.1 and B.2 provide vivid proof that someone driving Bridge (TZB) is a major Hudson River crossing north of from Boston to Virginia will hit a bottleneck at some time, New York City and is a well-known bottleneck in the road- almost certainly including a peak-period delay. The Coali- way network. It has been chosen as an example for this sec- tion's comprehensive program to deal with the I-95 corridor tion as it provides a good representation of a major highway as a single network, including (at some point) the forecast facility on U.S. roadways in the coastal mega-regions. It has for a 20-year timeframe, is not yet complete. Rather, this one also been chosen because, unlike most other U.S. highway example of an East Coast Mega-region bottleneck is presented facilities, it will likely receive a major upgrade of anywhere here, this time providing some forecast of its possible future from $5 billion to $15 billion within the next decade. The demand and its possible future capacity. (The project is cur- bridge is old and needs significant repair or replacement, like
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138 many other major U.S. highway facilities. It opened in 1955 and increased in any significant basis over existing infrastructure. carried an average of 18,000 vehicles daily in its first year. Now Therefore, the analyst must conclude that the answer to the the bridge carries a huge number of vehicles relative to its orig- issue of aviation capacity constraints as described in this inal design, which was considered a maximum of 100,000 vehi- report will not be provided in any significant way through cles per day. This extra capacity is carried with little change to additional roadway capacity. its original design: about 140,000 vehicles cross the 3.1-mi TZB every day, with daily volumes as high as 170,000. By 2030, B.2 Highway Demand and Capacity traffic in this corridor is expected to increase significantly, in the West Coast Mega-region with about 200,000 cars per day crossing the bridge. There is significant congestion on the bridge currently, even with a There are even more facilities on the West Coast on the variety of transportation demand management measures in INRIX list (B-2), as shown in Table B.3. These data are illus- place, such as variable toll pricing, tolling in only one direc- trated graphically in Figure B.1. tion, a movable barrier system, and the like. Overall, these data demonstrate that the highway systems Owing to both congestion issues and structural problems, the in both the East and West Coast Mega-regions are currently bridge is slated for either complete overhaul or replacement. operating at or near their effective capacities and, in the case of However, all replacement options offer little to no additional numerous bottlenecks, at severely degraded levels of service. auto capacity to absorb the forecast growth in auto traffic. For example, most alternatives being considered add only one addi- B.2.1 Future Increases in Capacity: tional travel lane over what currently exists now (eight lanes The California Statewide Model instead of seven, and two of those are high-occupancy toll/ Highway Network bus rapid transit lanes). As the East Coast Mega-region comprises several states-- Future capacity, future demand. The extra capacity esti- each of which has its own process for identifying and priori- mates for the TZB constitute an increase of 14% in auto tizing highway improvement projects--there is currently no capacity, assuming the high-occupancy toll lanes are fully single, consistent plan for the highway system nor any projec- used (significant transit improvements are also planned for tion of future traffic volumes and service levels. The I-95 Cor- all alternatives), whereas auto traffic is expected to increase ridor Coalition plans to develop ICAT in a way that could be from an average of 140,000 vehicles daily to 200,000. That is useful to that purpose, but that work will likely not be com- an increase in auto volumes of 43%. When one subtracts the pleted in time to be useful to this ACRP project. However, increased volume percentage from the increased capacity per- most of the major bottlenecks shown in the ICAT table are in centage, it is clear that the bridge will have 29% less capacity sections of facilities whose expansion would be extremely dif- than it will need--and this is after a major replacement ini- ficult and expensive. Therefore, it likely is safe to assume that tiative. This undercapacity will create significant congestion whatever highway improvements are implemented before and delay (although some corridor improvements will help 2025 would, at best, keep up with any increases in highway mitigate this, but only slightly). In other words, the bridge, traffic and more likely will not keep up with any growth, result- which today is already a highly congested facility, will be more ing in further declines in travel speeds. congested in 2030 than it is today--even with additional Without question, the roadways that make up the network capacity and significant infrastructure investment. carrying vehicles between the Northern California Mega- This example analysis leads the research team to conclude region and the Southern California Mega-region will experi- that, even with very expensive roadway investment and ence great increases in demand over the next 25 years. One improvement, roadway capacity issues will not be solved by such gateway, made up of I-5 and State Road 14, is estimated extensive capacity increases. There is not enough money to to register a 170% growth in demand between 2000 and 2030; build the infrastructure; even when there is, as in the case of I-5 and I-15 between LA and San Diego are forecast to grow the TZB, roadway capacity additions are dwarfed by future by 140%. The key cordon points in the study together show auto demand. In the TZB example, mobility is being improved an average 119% growth projected. based on the new TZB alternatives that create additional tran- Although it is difficult to forecast highway operating con- sit options--not highway capacity. This is no coincidence, as ditions as far as 25 years out, it appears from the available data planners for this improvement realize that high-volume tran- that bottlenecks that currently exist in the coastal mega- sit modes are the only way to increase mobility in this corri- regions highway networks are unlikely to be relieved over that dor cost effectively and realistically. time horizon. To test the relationship between future addi- Highway capacity, on the TZB and for most other loca- tional highway growth and improved highway travel speeds, tions, remains fairly stagnant and seems very unlikely to be the California modelers built a 2030 highway model.
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139 Table B.3. INRIX top 100 U.S. bottlenecks--West Coast highways (B-2). Rank Road County Hours Congested Avg. Speed when Congested 3 1 580 WB Marin 69 7.6 10 Hollywood Fwy SB Los Angeles 83 13.8 11 San Diego Fwy NB Los Angeles 81 15.5 13 Hollywood Fwy NB Los Angeles 79 12.9 14 Hollywood Fwy SB Los Angeles 75 15.0 18 Harbor Fwy NB Los Angeles 75 15.5 20 Hollywood Fwy SB Los Angeles 67 14.5 21 Hollywood Fwy SB Los Angeles 74 15.7 25 Harbor Fwy NB Los Angeles 71 15.7 27 Moreno Valley Fwy WB Riverside 72 14.7 28 Hollywood Fwy SB Los Angeles 55 13.1 29 I-238 NB Alameda 84 18.9 32 Hollywood Fwy NB Los Angeles 68 12.2 35 Hollywood Fwy NB Los Angeles 77 14.5 37 Harbor Fwy NB Los Angeles 63 14.6 38 Hollywood Fwy SB Los Angeles 79 17.9 40 Pomona Fwy EB Riverside 32 7.9 45 San Diego Fwy NB Los Angeles 61 17.2 50 Santa Monica Fwy EB Los Angeles 59 15.7 53 Riverside Fwy EB Orange 33 9.4 54 San Diego Fwy NB Los Angeles 55 15.4 55 Santa Ana Fwy NB Los Angeles 73 19.3 55 I-80 WB Alameda 41 11.0 58 Riverside Fwy EB Orange 32 9.3 60 Harbor Fwy SB Los Angeles 62 15.4 64 Pomona Fwy EB Riverside 29 8.3 65 Pomona Fwy EB Riverside 41 9.1 69 Santa Monica Fwy EB Los Angeles 60 15.9 71 Harbor Fwy SB Los Angeles 54 15.0 72 Pasadena Fwy NB Los Angeles 48 14.1 81 Harbor Fwy SB Los Angeles 53 15.5 83 San Diego Fwy SB Los Angeles 48 15.2 85 Harbor Fwy SB Los Angeles 43 13.5 85 James Lick Fwy NB San Francisco 40 10.2 88 Harbor Fwy SB Los Angeles 43 13.3 92 Hollywood Fwy SB Los Angeles 54 15.7 95 San Gabriel River Fwy SB Los Angeles 55 18.0 98 James Lick Fwy NB San Francisco 48 13.1 100 Santa Ana Fwy NB Los Angeles 61 19.1 B.2.2 Stability in Predicted Change in result in very little change in highway travel times--only Intercity Travel Times--West Coast small increases in most cases and no notable improvements. As part of the California HSR study, a multimodal travel forecasting model was developed, whose future highway net- B.3 Future Highway Capacity to work is shown in Figure B.2. In addition to representing cur- Respond to Aviation Demand: rent intercity travel conditions, the model includes forecasts Conclusion to the year 2030 that consider growth in population and employment, corresponding growth in traffic, and planned Table B.4 shows clearly that, even with the assumption major highway improvements. As shown in Table B.4, the net of new highway capacity, there does not seem to be any effects of all of those changes, however, were estimated to breakthrough that would invalidate the basic assumption
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140 Figure B.1. U.S. Highway bottlenecks (B-2). Figure B.2. The California 2030 highway network used in travel time calculations ( B-3). Table B.4. Predicted changes in intercity travel times on the West Coast (20002030) (B-3). Auto Air High-Speed Rail Conventional Rail City-to-City Pair 2000 2030 2000 2030 2030 2000/2030 Los Angeles downtown to 6:28 6:32 3:30 3:38 3:23 No service San Francisco downtown Fresno downtown to Los 3:32 3:38 3:17 3:24 2:14 No service Angeles downtown Los Angeles downtown to 2:37 2:39 2:51 3:01 2:13 3:26 San Diego downtown Burbank (airport) to San Jose 5:31 5:40 2:46 2:43 3:07 No service downtown Sacramento downtown to 2:29 2:24 2:41 2:41 2:15 4:06 San Jose downtown
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141 that the roadway system is highly used and that any future larger role in complementing the nation's air system than unmet needs at congested airports will not be mitigated they do now. by newly available reliable traffic flows on the roadway system. References The exception to this conclusion, though unexplored in this study of aviation capacity, is the chance that the roadways B-1. ICAT output tabulations provided February 2008 on both coastal regions might become more carefully man- B-2. INRIX--http://scorecard.inrix.com/scorecard/Top100WorstDetails. aspx retrieved 6/30/2008 aged, with the specific inclusion of managed lanes capable B-3. Cambridge Systematics, Bay Area/California High Speed Rail Rider- of supporting reliable bus service for short-distance ser- ship and Revenue Forecasting Study. Prepared for the Metropolitan vices such as BostonWashington, D.C., or Philadelphia Transportation Commission and California High Speed Rail Author- Washington, D.C. In this case, buses might play a significantly ity, July 2007.