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CHAPTER 8 Benefit-Cost Findings After exploring the calibration and modeling capabilities of the three reliability analysis tools, the study team examined the impact of including travel time reliability in benefit-cost analysis. This is a critical test of whether travel time reliability can influence project priorities. The time frame of the SHRP L38 project is too short to follow specific projects through the planning and decision-making process. However, benefit-cost analysis provides a good proxy. If the inclusion of travel time reliability changes the relative order of projects or causes marginal projects to have benefit-cost ratios above one, then travel time reliability is likely to influence project selection. In California, benefit-cost analysis is just one factor used in project selection. Caltrans uses benefit-cost analysis when selecting projects for the interregional portion of the State Transportation Improvement Program (STIP). A quasi-benefit-cost analysis is also used to select operations projects for the State Highway Operations and Protection Program (SHOPP). Local agencies use their own processes to select and promote projects. Despite these differences, decision makers are less likely to consider travel time reliability in project selection and prioritization if the value to users of travel time reliability is low relative to other project benefits. This section describes the procedure for and the results of the benefit-cost testing conducted at the Southern California pilot site for the I-5 and I-210 facilities. 8.1 Use of the C11 Tool The general approach for including travel time reliability was to update benefit-cost analyses from the I-5 and I-210 CSMPs. The CSMP benefit-cost analyses were built upon the microsimulation scenario testing and used the Cal-B/C framework to monetize the benefits. The Cal-B/C framework is described extensively in the Caltrans technical documentation for the model (System Metrics Group 2012). To add travel time reliability benefits, the study team used results from the SHRP 2 tools and monetized them by the Cal-B/C factors (Caltrans 2014) used for the CSMPs. The study team focused on the C11 tool because it was easier to calibrate and generated more realistic results than the L07 tool. The study team also considered using FREEVAL-RL, but the tool does not monetize travel time reliability benefits. The study team would have had to estimate the dollar value of reliability benefits outside FREEVAL-RL. In addition, the study team was able to calibrate FREEVAL-RL for only about 14 miles of the 45-mile I-5 facility due to limitations on the time and extent of congestion handled in the model. Although the study team did not use the FREEVAL-RL results in the benefit-cost test, the team did consider how agencies could use FREEVAL-RL output for estimating travel time reliability benefits. As shown in Figure 8.1, the FREEVAL-RL summary report lists a number of performance measures. Agencies could estimate the value of travel time reliability benefits using either the standard deviation or the 50th and 80th percentile TTI figures. 174
Figure 8.1. Example of FREEVAL-RL summary report from northbound I-5 a.m. Base model. Analyst: Guanqi 11/1/2013 14.9 64 76 0 Duration of Scenario (hrs) 4.0 0 1.31 Misery Index 2.05 1.27 0.22 1.55 58.02% 1.69 0.33% VHD Under Condition (Veh. Hrs) Total During RRP Average in 15 min %Time in Condition Recurring 1,130,108 270.62 97.3% Non- 78,190 18.72 2.7% Total 1,208,298 289.34 100.0% 1.1 1.28 1.8 2.8 79.83% 80.25% 20.17% 19.75% 99.68% 99.64% 0.32% 0.36% Total Number of Scenarios Number of Incident Scenarios Reliability Analysis Summary Report for FREEVAL Facility Description Facility Length (miles) Number of Weather Scenarios Numb. of Incident + Weather Scen. Facility Reliability Performance Measures Mean TTI 50th Percentile TTI Semi-Standard Deviation 80th percentile TTI Reliability Rating 95th Percentile TTI (PTI) Percent VMT at TTI > 2 Probability Distribution Function Cumulative Distribution Function Percent Contribution to Total Vehicular Hours of Delay (VHD) Analysis Details for Reliability Reporting Period by Congestion Status Scenarios with Recurring Congestion All Scenarios Maximum 15 min Segment D/C Ratio Maximum 15 min Segment D/C Ratio Maximum 15 min Facility TTI Maximum 15 min Facility TTI % VMT Unserved in the Study Period % VMT Unserved in the Study Period % Time with Queues on the Facility % Time with Queues on the Facility % Time without Queues on the Facility % Time without Queues on the Facility % VMT Served in the Study Period % VMT Served in the Study Period 0% 5% 10% 15% 20% 25% 30% 35% 40% 45% [1 ,1 .2 ) [1 .4 ,1 .6 ) [1 .8 ,2 ) [2 .2 ,2 .4 ) [2 .6 ,2 .8 ) [3 ,3 .2 ) [3 .4 ,3 .6 ) [3 .8 ,4 ) [4 .2 ,4 .4 ) [4 .6 ,4 .8 ) 5+ 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 1 1. 5 2 2. 5 3 3. 5 4 4. 5 94% 6% Recurring Non-Recurring 175
