Incorporating Reliability Performance Measures into the Transportation Planning and Programming Processes: Technical Reference (2014) / Chapter Skim
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Pages 94-101
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From page 94... ...
93 6 BENEFIT–COST ANALYSIS Color versions of the figures in this chapter are available online: http://www.trb.org/Main/Blurbs/168856.aspx Incremental benefit–cost analyses are used when alternatives are mutually exclusive and where an economical solution must be identified. An incremental benefit–cost analysis can reveal whether the incremental cost of a higher-cost project is justified by the incremental benefits gained (given all other factors being equal)
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94 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE The costs need to be developed for each analysis alternative; these costs are the same in any benefit–cost analysis. FHWA's Intelligent Transportation Systems Benefits and Costs report is a good guide to the costs of some of the congestion reduction strategies.
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95 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE The first term in Equation 6.4 accounts for the value of typical travel time, as measured by the median value. The median is selected for use here because if the overall mean TTI were used, it would include some of the variability from the travel time distribution, leading to double counting when the reliability term is added.
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96 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE 6.2 APPLICATION TO MODEL POST-PROCESSING METHODS If IDAS is being used as the model post-processor, the benefit–cost calculation is completed within the tool itself. However, not all strategies are included in IDAS, and only incident-related delay is assessed within the tool.
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97 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE TTI80 = 1 + 2.1406 * ln(TTImean)
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98 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE SEMCOG decided to apply sketch-planning methods to estimate total delay in the corridor. The staff reduced the geographic scope of the analysis by using representative freeway corridors with operational characteristics (e.g., average traffic volume, interchange density, directional flows, and surrounding land use)
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99 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE To estimate regional benefits, they extrapolated the benefits of the study corridor to representative corridors and then to the region as a whole. This allowed them to develop an improved performance curve to compare funding levels to reliability performance in conjunction with average travel time performance (Table 6.3)
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100 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE 6.7 REFERENCE 1. Small, K.A., C
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