Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Technical Feasibility of Products The L02 guide provided a number of new analysis techniques and ways of looking at the causes of unreliability. The CDFs and the percent contribution tables help to show the relative contribution of reliability factors and visualize their impact on facility reliability. The study team found that the order in which factors are assigned affects the results of the analysis. The analysis should include categories for multiple factors (e.g., incidents and weather issues occurring simultaneously) and specifically consider factors such as work zones and lane closures. These reliability analysis techniques could be incorporated into future CSMPs, which was an interest expressed by regional stakeholders who reviewed the findings from this project. The bulk of the testing, documented in Chapters 5 through 7 of this report, is devoted to calibrating the three reliability analysis tools (from L07, L08, and C11) and using these tools to test improvement strategies. The study team found that these tools could be calibrated to baseline conditions after appropriate calibration levers such as capacity, hourly demand, and adjustment factors were identified. None of the tools had built-in capabilities to model the types of operational projects most likely to be tested in California, including ramp metering, ramp improvements, auxiliary lanes, and freeway connectors. The SHRP 2 reliability tools should be updated to handle these types of improvements. Since the tools were unable to model key operational strategies used in Southern California, the study team had to rely on microsimulation modeling to estimate the changes in capacity needed to test the strategies in the SHRP 2 tools. With these inputs, the toolsâ estimated reliability impacts were lower than expected, and these impacts were highly correlated with mobility (or recurring delay) results. In fact, reliability benefits fell in a narrow range between 29 percent and 36 percent of total benefits. The study team found that there was a clear order in terms of ease of use among the SHRP 2 reliability tools (Figure ES.7). The C11 and L07 tools were much easier to use than the FREEVAL-RL tool. The study team had intended to split the analysis among SCAG and other team members, so that agency and consulting staff used all of the tools. The team quickly discovered that calibrating the FREEVAL-RL tool was complicated, so the calibration was assigned only to modelers on the pilot study team. Figure ES.7. SHRP 2 reliability tools by ease of use. 10
