Pilot Testing of SHRP 2 Reliability Data and Analytical Products: Southern California (2014)

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input sources. This document provides supporting detail for Chapter 3 (Computational Methods). • Appendix C: Case Studies presents six detailed case studies that exercise various aspects of the guide, including system architecture, analysis of recurrent and nonrecurrent sources of congestion, and the application of a variety of use cases. • Appendix D: Use Case Demonstrations illustrates the application of a variety of use cases for a travel time reliability monitoring system. This document provides supporting detail for Chapter 4 (Applications). 4.3 Evaluation of the L02 Guide General Assessment of the Guide Below, the study team provides a general assessment of the guide and makes recommendations based on its application of the guide to the Southern California pilot site. Following this section, the remaining three sections of this chapter address how the study team followed the three focus areas of the guide (i.e., calculating average route travel times, AE1 Use Case, and AE2 Use Case). Those sections provide a more detailed assessment of issues encountered while using the guide. Technical Language With the inclusion of supplements and appendices, the L02 guide has 635 pages of very technical information. While this level of detail may be necessary for the development of a robust TTRMS, the study team found that it makes the guide difficult to understand by the practitioners to which it is directed. Discussions of “disutility functions,” “probability density functions,” and “semi-variance” among other economic or statistical terms are difficult for practitioners to understand. Some terminology used throughout the guide is not consistent with standard practice in transportation planning. For example, the term “nominal loading” in the guide represents the congestion level, but is more commonly known to practitioners as the “peak period.” “Multimodal” in the guide is a statistical term that the guide defines as “one point at which the probability density function reaches a maximum” (e.g., when weather and incidents both occur during the same time period). Transportation practitioners, however, refer to “multimodal” as representing different modes of travel, such as single occupant automobile, public transit, or walking. Although the guide does make this distinction and uses the term “regime” instead of multimodality, the term “multimodal” is still used throughout the guide to describe the statistical meaning. The language in the manual could be streamlined to appeal to day-to-day managers and operators of the transportation system. 43