Click for next page ( 64


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 63
63 ATTACHMENT Guide for Pavement-Type Selection: Summary of Research Report

OCR for page 63
64 CONTENTS 65 Introduction 65 Research Objective, Scope, and Summary 65 Summary of Findings 69 References

OCR for page 63
65 Introduction Research Objective, Scope, and Summary Pavement-type selection is one of the challenging engi- neering decisions that highway administrators face today. The objective of NCHRP Project 10-75 was to develop a They must balance issues of both short- and long-term per- Guide for Pavement-Type Selection. The Guide includes formance with initial and long-term costs. The traveling pub- processes for making decisions regarding pavement-type lic generally does not express strong feelings on the type of selection, for both agency-based and contractor-based type pavement constructed, as long as reasonable levels of service, selection. This objective was accomplished in two phases. safety, and ride quality are provided. However, highway admin- Work scope and findings are summarized in the following istrators must deal with the competition that exists between the sections. asphalt and concrete pavement industries. National Coopera- Phase I included (1) collecting and reviewing information tive Highway Research Program (NCHRP) Project 10-75 was relevant to pavement-type selection processes, (2) identify- conducted to develop a rational process for pavement-type ing and evaluating traditional and innovative processes for selection. pavement-type selection, and (3) developing a plan for incor- One of the earliest discussions about pavement-type selec- porating the best practices identified into a practical guide. tion was contained in An Informal Guide on Project Proce- Phase II utilized the findings of Phase I to develop, test, and illus- dures, published by the American Association of State Highway trate the processes suggested for use in agency- and contractor- Officials (AASHO) on November 26, 1960. The guide pre- based pavement-type selection and then incorporated these sented the following list of governing factors to serve as the processes into a Guide for Pavement-Type Selection. basis of pavement-type selection: Information on current pavement-type selection processes used by the state departments of transportation (DOTs) and "To avoid criticism, if that is possible, any decision as to paving international highway agencies was obtained through a type to be used should be firmly based. Judicious and prudent con- sideration and evaluation of the governing factors will result in a questionnaire. In addition, state agency web sites were vis- firm base for a decision on paving type. ited to review available policy documents. The questionnaire A list of such factors comprises the following items: requested information on how certain factors (pavement per- formance life, discount rate, agency cost) were developed and 1. Traffic. other information that was not always apparent in the available 2. Soils characteristics. 3. Weather. published operational documents. Also requested was infor- 4. Performance of similar pavements in the area. mation on planned changes and ongoing research. Thirty- 5. Economics or cost comparison. three state DOTs responded to the survey. 6. Adjacent existing pavements. Because the questionnaires elicited limited data on design- 7. Stage construction. build contractor pavement-type selection, additional searches 8. Depressed, surface, or elevated design. were conducted to locate current research and review request 9. Highway system. 10. Conservation of aggregates. for proposal (RFP) documents that had been issued by state 11. Stimulation of competition. DOTs. 12. Construction considerations. A brief questionnaire also was sent to each of the states' flex- 13. Municipal preference, participating local government ible and rigid contractor paving associations requesting feed- preference and recognition of local industry. back on the pavement-type selection procedures used in their 14. Traffic safety. 15. Availability of and adaptations of local materials or of respective states. local commercially produced mixes." The information gathered was reviewed, evaluated, and summarized. The initial work plan for developing the Guide for This list served as the basis for selection of pavement type on Pavement-Type Selection was updated based on this informa- the Interstate system, as well as the basis for the guidance pro- tion and implemented in Phase II. vided in the 1986 and 1993 editions of the AASHTO Guide for Design of Pavement Structures. The list is still relevant today Summary of Findings and serves as a foundation for the Guide for Pavement-Type Selection prepared in this project. The development of the Table 1 lists state DOTs' responses regarding the use of MechanisticEmpirical Pavement Design Guide (MEPDG), pavement-type selection procedures. pavement management systems, and extensive maintenance Twenty-two of the 35 state DOTs responding have a for- and rehabilitation (M&R) cost records makes the development mal type-selection process that requires the consideration of of more rational and less subjective pavement-type selection alternative pavement types on major new and reconstruction procedures possible. projects.

OCR for page 63
66 Table 1. State DOT pavement-type selection procedures. Pavement Events Current Pavement-Type Selection Procedure Warranting Type Selection State Length Of Time Procedure Modifications To Projects Using Alternate New Re- Current Procedure Modified In Current Procedure Bidding To Select Const Const Rehab Has Been Used, Years Last 5 Years? Underway? Pavement Type Alabama Y Y N 10 Y N <1 Arizona1 Y1 Y1 Y1 23 N N 0 Arkansas Y Y Y 10 Y N NR California Yes Yes Yes 2 No No 0 Colorado NR NR NR NR NR NR Considering 1 Delaware NR NR NR NR NR NR 0 Georgia Y Y Y 5 Y Y NR Idaho Y Y Y 20 Y Y 1 Illinois Y Y N 20 N Y 0 Indiana Y Y Y 2 Y Y NR Kansas Y Y Y 30 Y Y 1 Louisiana Y Y NR NR NR NR 44 Maine2 N2 N2 N2 N/A N/A N/A 0 Maryland Y Y N 3 Y N 0 Michigan Y Y Y 10 N N 0 Minnesota Y Y N 15 Y N 0 Missouri Y Y Y 4 Y N >100 Montana3 N3 N3 N3 N/A N/A Y 1 Nebraska4 N/A4 N/A4 N/A4 N/A N/A N/A Several Nevada5 Y5 N N 12 N Y NR New Hampshire Y Y Y 10 N Y 0 New Mexico6 Y6 Y6 Y6 >5 Y Y 0 North Carolina Y Y N 18 N N 4 to 5 North Dakota Y Y Y 30 N N 0 Ohio Y Y Y 4 Y N 2 Pennsylvania NR NR NR NR NR NR 2 to 3 South Carolina Y Y N 5 Y Y 0 South Dakota Y Y Y 14 N N 0 Tennessee7 Y7 Y7 Y7 20 N Y 1 Texas8 Y8 Y8 NR NR Y Y 0 Utah Y Y N Few Y N 0 Vermont Y Y N 10 Y Y 0 Washington Y Y N 5 N N 0 West Virginia Y Y Y 5 N N 0 Wisconsin Y Y Y 15 Y Y 0 1 Arizona does not have a formal process for pavement-type selection. However, guidelines are provided in their Preliminary Engineering and Design Manual. 2 Maine has no selection process, since they build only hot-mix asphalt (HMA) pavements. 3 Montana does not have a formal policy for pavement-type selection since they historically have built only HMA pavements. However, because of recent asphalt price escalation, they are performing informal pavement-type selection. 4 Nebraska does not have a formal procedure. The decision is based on funding, constructability, traffic, and life cycles. 5 The Nevada Department of Transportation Director and the Principal Materials Engineer are responsible for type selection. While a life-cycle cost analysis (LCCA) may be made, it is not always considered in the final selection. 6 New Mexico's procedure is informal with the selection made by a team. 7 Tennessee's procedure is not documented and is not required for all projects. 8 In Texas, type selection is ultimately at the District's discretion. NR = no response; N/A = not applicable.

OCR for page 63
67 Of these 22 state DOTs, 21 require a life-cycle cost analysis alternatives is established by including a bid adjustment factor (LCCA). Ten of the states have specific criteria for considering to account for the difference in discounted future M&R costs the results of the LCCA. Ten states stipulate that if the differ- between alternatives. With more alternative choices for selec- ence in life-cycle costs exceeds a specified amount (ranging tion, the agencies are believed to realize significant cost savings from 5 to 20 percent), the lower cost alternative usually will be from competition in the pavement industry, given the fact that selected. Michigan DOT is required by law to select the alter- large fluctuations in material costs can occur between the time native with the lowest life-cycle cost. of design and the bid letting. Twenty-nine of the 35 responding state DOTs perform In traditional design-bid-build contracts, the contractor LCCA for new construction/reconstruction projects, out of delivers construction services as defined in the standard plans which 22 report having formal procedures, 6 indicate use of a and specifications issued by the highway agency. The contrac- probabilistic process, and 14 indicate consideration of user tor assumes no responsibility for the delivered product except costs in the analysis. Thirteen DOTs perform LCCA for reha- a limited-time warranty for materials and workmanship qual- bilitation projects. Most DOTs utilize the net present value ity. The agency assumes the entire responsibility and risk for (NPV) method for computing life-cycle costs, and most use design, construction, and post-construction performance of either a custom-developed spreadsheet or the Federal Highway the pavement. Administration (FHWA) probabilistic LCCA program Real- With the inception of alternative contracting methods, the Cost. Of the 14 DOTs that consider user costs, most focus on contractor's role has extended into nontraditional services such the time delay and vehicle operating cost (VOC) components as design, operations and maintenance, and performance war- associated with work zones. In addition, five of these 14 DOTs ranty. To address the shifts in responsibilities and risks effec- combine user costs with agency costs to generate a total life- tively, agencies use contract provisions to communicate the cycle cost, while the other eight DOTs keep the two costs sep- project scope, performance/design criteria, and other require- arate. Table 2 summarizes the LCCA approaches used by the ments in the RFP. The contractor is obligated to provide the responding DOTs. product and services specified in the contract provisions with In addition, most DOTs had some type of process to consider certain technical, cost, time, and quality requirements. noneconomic factors in making their pavement-type selection In design-build contracting, the agencies typically have when the LCCA did not indicate a clear preference. This process procured contractor services for only design and construction generally was subjective, with the decision being made by either phases of the projects involving limited-time warranties. In the an individual or a selection committee. Noneconomic factors absence of long-term warranties, the agencies assume respon- often considered in pavement-type selection include: sibilities for managing future performance risks. Considering the short turnover period and limited warranty, the agencies 1. Traffic. usually stipulate the pavement types to be used in a project and/ 2. Soils characteristics. or specify the criteria to be followed in the selection process. 3. Weather. However, in projects where contractors have long-term 4. Performance of similar pavements in the area. responsibilities for operations and maintenance, agencies have 5. Economics or cost comparison. allowed the contractors to specify the pavement types. In such 6. Adjacent existing pavements. projects, the contractors were required to follow the project 7. Stage construction. requirements specified in the RFP. 8. Depressed, surface, or elevated design. Based on the analysis of the Phase I findings, it was con- 9. Highway system. cluded that the pavement-type selection process should have 10. Conservation of aggregates. the following key components: 11. Stimulation of competition. 12. Construction considerations. Criteria specifying the type of projects for which the 13. Local government preference and recognition of local pavement-type selection process should be applied. industry. A formal process for the identification of pavement-type 14. Sustainability. alternatives to be considered. The selection of potential alter- 15. Traffic safety. natives should be based on a comprehensive and transpar- 16. Availability of local materials or locally produced mixes. ent process involving the agency, contractors, and the paving industry. It is expected that alternatives reflect national Several state agencies have experimented with alternate practices, regional experience, type and size of projects, and pavement-type bidding. In this approach, the bidders are per- type of traffic the pavement is expected to carry. To max- mitted to select a pavement type among two or more equiva- imize the economic value, the agency should consider lent alternatives provided by the agency. The equivalency of alternatives that stimulate completion and incorporate

OCR for page 63
Table 2. State DOT LCCA procedures. LCCA Approach LCCA Package Used Perform FHWA State-Customized Proprietary/ State Determi Proba Consider Use State-Developed AASHTO LCCA NPV EUAC Probabilistic Version of Industry nistic bilistic User Costs Spreadsheet/Software Darwin Spreadsheet RealCost RealCost Software Alabama Y Y N Y N N N N N N Y Arizona Optional Y N Y N Y N Y N N N Arkansas Y Y N Y N N Y N N N N California Y Y N Y N Y N N Deterministic only No No Colorado Y Y N N Y Y N Y N N Y Delaware Optional N Y Y Y Y N Y N N N Georgia Y Y Y Y N Y Y N N N N Idaho Y Y Y Y N N Y N N N N Illinois Y N Y Y N N Y N N N N Indiana Y Y Y N Y N N Y N N N Kansas Y Y N Y N Y Y N N N N Louisiana Y Y N Y N Y N N Y N N Maine N N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Maryland Y Y N N Y Y N Y Y N N Michigan Y N Y Y N Y Y N N N N Minnesota Y Y N Y N N Y N N N N Missouri Y Y N Y N N Y N N N N Montana Optional Y N Y N N Y N N N N Nebraska Optional NR NR NR NR NR NR NR NR NR NR Nevada Optional Y N Y N N Y N N N N New Hampshire N N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A New Mexico Optional Y N Y N Y Y N N N N North Carolina Y N Y Y N N Y N N N N North Dakota N N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Ohio Y Y N Y N N Y N N N N Pennsylvania Cost > $15M Y Y Y N Y Y N N N N South Carolina Y Y N Y Y Y Y Y N N N South Dakota N NR NR NR NR NR NR NR NR NR NR Tennessee N Y Y Y N N Y Y N Y Y Texas Optional N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Utah Y Y N Y N N Y Y N N N Vermont Y Y N Y N Y N Y N N Y Washington Y Y N Y Y Y N Y N Y N West Virginia Y Y N Y N N N N N N Y Wisconsin Y N Y Y N N Y N N N N Note: EUAC = equivalent uniform annual costs; NA= not applicable; NR = no response.

OCR for page 63
69 innovative approaches. This activity should be overseen by contractor-based selection. In either case, the contractor can a pavement-type selection committee composed of agency follow the agency's selection process (including life-cycle design, construction, and maintenance personnel. assumptions) or any other similar process accepted by the Procedures for the estimation of pavement service life. Tech- agency. niques range from expert modeling using the opinions of On alternative contracting projects (design-build, design- experienced engineers to detailed performance-prediction build with operations and maintenance, and long-term per- modeling using historical performance data to develop sur- formance warranty methods), the agency should perform a vival curves. risk analysis to determine the contractor's scope and how A framework for the LCCA. The analysis period should stringent the contract provisions for pavement-type selec- be sufficiently long to distinguish any differences between tion should be. pavement alternatives and long enough such that each alter- In design-build projects involving operations and mainte- native pavement strategy includes at least one future major nance responsibilities and long-term performance warranty, rehabilitation event. The discount rate should be based on the contractor assumes the risks associated with post- economic factors established by the agency or the Office of construction for an extended period of time. In such cases, Management and Budget (OMB) Circular A-94 Appendix the contractor selection process is stipulated largely by the C. The process must include procedures for estimating cur- performance criteria specified in the RFP. rent and future costs. Both agency and user costs should be If a considerable length of time elapses between the original evaluated, and supplemental costs such as those incurred pavement-type selection and a call for bids, the selection for contract administration, engineering, and traffic control should be reviewed to ensure that conditions have not may be considered if significantly different for pavement- changed. type alternatives. However, user and agency costs should be evaluated separately, because the dollar value of user costs An overview of the process is shown in Figure 1. often is significantly greater than that of agency costs. The The Guide for Pavement-Type Selection developed under LCCA methodology may be computed deterministically or this project contains a comprehensive set of procedures, probabilistically, and general guidance such as that devel- including an alternative preference screening matrix that oped by Walls and Smith (1998) should be followed in the highway agencies can use to develop pavement-type selection development of the procedures. policies and processes. Each step is described, and the factors An alternative screening matrix should be utilized to weigh that should be considered are identified. Because of differ- both the economic (initial, rehabilitation, maintenance, and ences in agency decision-making processes, it is expected that user costs) and noneconomic (geometrics, pavement and each agency will adapt these procedures to meet its specific lane continuity, traffic during construction, availability of needs. local materials, local preference, noise, safety, sustainability) Details on research performed in this project are documented factors in comparing alternatives. The factors and ratings in the project research report, available on the NCHRP Report should be established based on local conditions. 703 web page at http://www.trb.org/Main/Blurbs/165531.aspx. Alternate bidding is a variation of the design-bid-build process, where the agency provides complete designs for two References or more equivalent pavement alternatives and selection is based on the alternative receiving the lowest bid. Alternate American Association of State Highway and Transportation Officials bidding should be used for projects having alternatives with (AASHTO), Guide for Design of Pavement Structures, AASHTO, Washington, D.C., 1993. equivalent designs where the analysis of economic and American Association of State Highway Officials (AASHO), An Infor- noneconomic factors does not indicate a clear preference mal Guide on Project Procedures, AASHO, Washington, D.C., 1960. between alternatives. Office of Budget and Management, Discount Rates for Cost-Effectiveness, In design-build projects (where the contractor assumes no Lease Purchase, and Related Analyses, Circular A-94 Appendix C, operational responsibilities and provides no extended war- 2010. http://www.whitehouse.gov/omb/circulars_a094/a94_appx-c (as of March 29, 2011). ranty), the agency is responsible for risks associated with Walls, J., and Smith, M. R. Life-Cycle Cost Analysis in Pavement Design, future performance. In such cases, the agency stipulates the Interim Technical Bulletin, Report No. FHWA-SA-98-079, Federal preferred pavement alternative(s) or specifies the criteria for Highway Administration, Washington, D.C., 1998.

OCR for page 63
70 Agency planning and programming Identify appropriate contract type for the project YES Is the contract type design-bid-build? NO Alternatives from Is project pavement-type NO suitable for contractor- YES selection committee based pavement-type selection? Agency-based Contractor-based pavement-type selection pavement-type selection Identification of feasible Agency develops contract alternatives for project provisions Contractor reviews contract Development of pavement life provisions and agency cycle strategies practices Contractor makes adjustments Life cycle cost analysis to inputs of agency-based selection process Evaluation of economic and Design-build operate & Performance noneconomic factors Design-build maintain warranty Agency-based selection of preferred pavement types Contractor selects an alternative for the proposal Alternate bidding- Design-bid-build- Contractor-based selection preferred pavement types preferred pavement type of preferred pavement type Figure 1. Overview of the pavement-type selection process.