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Suggested Citation:"Chapter 7 - Alternatives Analysis." National Academies of Sciences, Engineering, and Medicine. 2008. Cost-Effective Performance Measures for Travel Time Delay, Variation, and Reliability. Washington, DC: The National Academies Press. doi: 10.17226/14167.
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Suggested Citation:"Chapter 7 - Alternatives Analysis." National Academies of Sciences, Engineering, and Medicine. 2008. Cost-Effective Performance Measures for Travel Time Delay, Variation, and Reliability. Washington, DC: The National Academies Press. doi: 10.17226/14167.
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Page 53
Suggested Citation:"Chapter 7 - Alternatives Analysis." National Academies of Sciences, Engineering, and Medicine. 2008. Cost-Effective Performance Measures for Travel Time Delay, Variation, and Reliability. Washington, DC: The National Academies Press. doi: 10.17226/14167.
×
Page 53
Page 54
Suggested Citation:"Chapter 7 - Alternatives Analysis." National Academies of Sciences, Engineering, and Medicine. 2008. Cost-Effective Performance Measures for Travel Time Delay, Variation, and Reliability. Washington, DC: The National Academies Press. doi: 10.17226/14167.
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Page 54

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51 7.1 Introduction This chapter describes how to identify alternative im- provements or strategies to mitigate identified existing or fu- ture deficiencies and how to determine which improvements are most effective in addressing those deficiencies. It goes on to provide guidance on how to assess the effectiveness of im- provements once they are in the field. 7.1.1 Purpose The purpose of this chapter is to help the analyst avoid common pitfalls in the evaluation of alternatives for reducing travel time, delay, and improving reliability. These common pitfalls include the following: • Selection of improvements that solve a problem that is dif- ferent from the real problem, that is, the search for solutions is misdirected; and • Overlooking improvements that could solve the problem, that is, the search is too narrow. 7.1.2 Scope and Limitations This chapter covers the generation, evaluation, and pro- gramming of transportation system improvements designed to reduce travel time, reduce delay, and increase reliability. This chapter is necessarily brief and is not designed to replace standard planning textbooks on alternatives analysis. “Alternatives analysis” in this context is informal and refers to a generalized analytical process of evaluating different pos- sible operational strategies, capital projects, etc., to determine the benefits of each and help the analyst draw conclusions about which course of action is likely to be the most effective in addressing the identified deficiency or problem. The term as used here should not be equated with the formal alterna- tives analysis process described in federal requirements for preparation of Environmental Impact Statements or for entry into the Federal Transit Administration (FTA) Section 5309 New Starts project development process and funding program. While the methods described here can be used to support a formal alternatives analysis process, the entire process is not discussed here. 7.1.3 Organization The chapter is organized into the following six steps: 1. Problem definition; 2. Generation of project alternatives for analysis; 3. Selection of performance measures; 4. Evaluation of alternatives; 5. Develop improvement program; and 6. Effectiveness evaluation (before/after studies). 7.2 Defining the Problem Before embarking on developing alternatives, the problem to be solved by the alternative improvements must be defined. The first step in alternatives analysis is to identify and diagnose deficiencies in current or forecasted system opera- tions, as described in Chapters 5 and 6, respectively. The more precisely the analyst can define the problem that the alternative improvements are supposed to solve, the more pre- cisely the analyst can focus the analysis. The problem definition drives the entire alternatives analysis process, from generation of improvement alternatives, to the selection of performance meas- ures for evaluating each improvement option. Example problem definitions that this guidebook is de- signed to address include: • Peak-period delay exceeds agency’s performance targets; and • Travel-time reliability during off-peak periods is below agency’s standards. C H A P T E R 7 Alternatives Analysis

52 Problem Solution Strategies Improvement Alternatives Excessive Peak-Period Delay (on average day without incidents) Likely Cause Peak Demand > Capacity Travel Demand Management to shift demand to other corridors, other time periods, and/or other modes. Establish TDM Program for Employers Staggered work hours Construct Transit improvements Increased transit service Construct HOV lanes Carpool parking Construct bypass for bottleneck(s) Peak-hour tolls Auto restricted zones Service vehicle hour restrictions Parking supply management Concierge shopping services Satellite work stations Work at Home Program Ramp and signal metering Increase capacity at bottlenecks. Add lanes Change signal timing Correct substandard geometry Allow peak period shoulder lane use Reversible lanes Peak period turn prohibitions Ramp metering Heavy vehicle restrictions Exhibit 7.1. Alternative improvements to solve delay problems. 7.3 Generation of Project Alternatives for Analysis The analyst should consult one or more of the following references for strategies and actions that are appropriate for reducing travel time, delay, and variability. Exhibits 7.1 and 7.2 highlight some of the actions and strategies discussed in these references, but should not be considered a replacement for consulting these references. 1. Unclogging Arterials: Prescriptions for Relieving Conges- tion and Improving Safety on Major Local Roadways (FHWA-OP-03-069) (2003). This guidebook presents 15 strategies for increasing mo- bility and safety of travel on arterial streets. The guidebook also contains 10 case studies of local agencies that have em- ployed these strategies, an action checklist and appendices showing example documents, such as memoranda of un- derstanding and city legislation that readers can use as mod- els in their own areas. Contact the Operations/ITS Helpline, (866) 367-7487 or itspubs@fhwa.dot.gov. 2. A Toolbox for Alleviating Traffic Congestion and Enhancing Mobility (1997). This document provides local elected officials, busi- ness leaders, and other community leaders with infor- mation on traffic congestion and strategies that can be used to deal with it. Types of strategies discussed include increasing transportation capacity (both through widening or expansion of roads, and new techniques such as ITS), public transportation, demand manage- ment, and funding and other institutional issues. For each strategy, the report provides a description, the es- timated costs and benefits, steps needed to implement it successfully, and a detailed bibliography. Available at http://www.itsdocs.fhwa.dot.gov/jpodocs/repts_te/5dz01! .pdf, EDL# 6983. Also available: Michael D. Meyer, A Toolbox For Alle- viating Traffic Congestion And Enhancing Mobility, In- stitute Of Transportation Engineers, Washington, D.C., 1996 (available at http://ntl.bts.gov/lib/8000/8700/8780/ toolbox.pdf).

53 Problem Likely Cause Solution Strategies Improvement Alternatives Excessive Variability in Peak Travel Times Demand exceeds capacity, and incidents are too frequent and too damaging Reduce probability of incidents. Bring road design up to agency standards Accident history investigation Vehicle regulations Reduce roadside distractions Reduce in-vehicle distractions Reduce incident detection times. Real-Time Monitoring of traffic flow Improve emergency response times. Establish roving response teams Service patrols Reduce incident clearance times. Integrate 911 emergency responders and maintenance operations Contract towing services dedicated to road sections Off-road pullouts for exchanging accident info Reduce impacts of incidents on capacity. Wider shoulders Off-road pullouts for exchanging accident info Gawker Screens Traveler information systems to help people avoid incident locations. Exhibit 7.2. Alternative improvements to solve reliability problems. 3. TCRP Report 95: Traveler Response to Transportation Sys- tem Changes. Includes discussion of transit scheduling and frequency, and other operational actions that impact ridership. 4. TCRP Report 100: Transit Capacity and Quality of Service Manual, Second Edition, TRB, Washington, D.C., 2003. This comprehensive manual includes information on capital and operating strategies for bus, rail, and water transit, covering vehicles, routes/alignments, and stations. 7.4 Selection of Performance Measures Performance measures (also called measures of effective- ness, or M.O.E.) are the system performance statistics that best characterize the degree to which a particular alternative meets the agency’s objectives. Chapter 2 describes the selection of appropriate measures of effectiveness for evaluating current operations, future operations, and alternatives for reducing travel time, delay, and variability. The selected set of performance measures should be as sparse as possible, consistent with the defined problem. A large set of measures strains the analyst’s resources and increases the probability of conflicting results, clouding the selection and prioritization process. 7.5 Evaluation of Alternatives Once the problem to be solved has been defined, the performance measures selected, and the alternatives to be eval- uated have been identified, then the evaluation of the effec- tiveness of each alternative is generally quite straight forward. The analyst uses the methods described in Chapters 2 and 3 to estimate the travel-time, delay, and reliability measures that will be used to compare the performance of each im- provement alternative. For example, if analysts were to define their problem as ex- cessive delay and excessive unpredictability in the delay, then they might select the mean person-hours of delay and the variance in the person-hours of delay as their performance measures. The analyst might then develop four alternative im- provement strategies for addressing the problem. They might be: do nothing, add capacity (Alt. A), manage demand (Alt. B), and improve incident response (Alt. C). Computa- tion of the person-hours of delay and their variance might present results like those shown in Exhibit 7.3. (Person-hours traveled are shown as well as delay, because the total person- hours traveled is needed to obtain delay.). The question then becomes, “Which alternative is best?” If simply looking at the mean person-hours traveled, then you would select Alternative A as the best, since it provides

54 Mean Variance Alternative Person Hours Traveled Person Hours of Delay Person Hours Traveled Person Hours of Delay Do Nothing 1,230,000 61,500 184,500 15,375 Alternative A 1,199,250 30,750 119,925 6,150 Alternative B 1,214,625 46,125 145,755 9,225 Alternative C 1,223,850 55,350 171,339 5,535 Exhibit 7.3. Example results of alternatives evaluation. the lowest mean person-hours of delay. If simply looking at the variance of the delay, then you would select Alternative C since it produces the lowest variance in delay. The analyst needs to introduce other information such as monetary, societal, and environmental costs to the evaluation of alternatives. This might be done through a cost-effectiveness analysis over the lifetime of each alternative. There are several references available for guidance on conducting this type of analysis. They include: 1. Economic Analysis Primer, U.S. Department of Trans- portation, Federal Highway Administration, Office of Asset Management, FHWA-IF-03-032 (web document), August 2003. It is available at: http://www.fhwa.dot.gov/ infrastructure/asstmgmt/primer.htm. 2. NCHRP Synthesis 142: Methods of Cost-Effectiveness Analysis for Highway Projects, Transportation Research Board, Washington, D.C. 1988. 3. AASHTO Red Book – American Association of State High- way and Transportation Officials: A Manual on User Bene- fit Analysis of Highway and Bus Transit Improvements, 1977. (See also final report for NCHRP Project 2-23, Development of an Update to the 1977 AASHTO Redbook.”) A weighting scheme is then developed by the analyst (re- flecting the relative importance to the agency of minimizing costs and achieving each objective). The relative weight of each cost and each objective is combined to yield a single nu- merical value for each alternative. The recommended alter- native is the one with the best overall numerical value. 7.6 Develop Improvement Program Once the best alternative has been selected it is necessary to develop a program for implementing the improvements. This program identifies responsible agencies, sources of funds, and a schedule for improvements. An implementation monitor- ing program is useful to ensure that the improvements are implemented as planned. 7.7 Evaluate Effectiveness of Implemented Solutions An evaluation of the effectiveness of the solution(s) that have been implemented can be conducted using the before and after methods described in Chapter 4. Because this requires forethought in setting up the before/after comparison and defining data collection needs prior to actual implementation, the decision to conduct this type of effectiveness evaluation needs to be made early, and certain actions taken before con- struction of the chosen improvement (or initiation of a new service or program, if a noncapital improvement).

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TRB's National Cooperative Highway Research Program (NCHRP) Report 618: Cost-Effective Performance Measures for Travel Time Delay, Variation, and Reliability explores a framework and methods to predict, measure, and report travel time, delay, and reliability from a customer-oriented perspective.

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