Establishing Monitoring Programs for Travel Time Reliability (2014) / Chapter Skim
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Pages 88-101
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88 This section describes the case studies and use cases employed to test the ideas presented in the Guide for a travel time reliability monitoring system (TTRMS)
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89 Because this technical and institutional infrastructure was already in place, the team focused on generating sophisticated reliability use case analyses. The rich, multimodal nature of the San Diego data presented numerous opportunities for state-of-the-art reliability monitoring, as well as challenges in implementing Guide methodologies on real data.
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90 Freeway Analyses Freeway Use Case 1: Conducting offline analysis on the relationship between travel time variability and the seven sources of congestion. This use case is primarily for the system planner and roadway manager user types.
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91 considerations for integrating a TTRMS into existing data collection systems. The purpose of this case study was as follows: • Describe the data acquisition and processing steps needed to transfer information between the existing system and the PeMS reliability monitoring system.
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92 Agencies interested in acquiring PeMS or a similar system can take steps to make this integration go more smoothly and quickly. First, it is important that the implementation and maintenance of a traffic data collection system be carried out with a broad audience in mind.
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93 95th percentile travel times for each condition. The methodological findings of this investigation are that multistate normal distribution models can approximate travel time distributions generated from loop detectors better than normal or lognormal distributions.
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94 ETC and Bluetooth devices, are extremely new and are not currently integrated into Caltrans District 3's existing PeMS data feed. Consequently, it was necessary to incorporate these data sets into project-specific instances of PeMS for analysis as part of this project.
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95 case study should be required to submit an affidavit indicating that they will not use data collected on the agency's behalf in an inappropriate manner. Integration of Sources of Nonrecurring Congestion The purpose of this use case was to quantify the impact of adverse weather- and demand-related conditions on travel time reliability using data derived from the case study's Bluetooth- and ETC-based systems deployed in rural areas.
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96 Navigator was initially deployed in metropolitan Atlanta in preparation for the 1996 Summer Olympic Games. Navigator collects lane-specific volume, speed, and occupancy data in real time and stores it in a database table for 30 minutes.
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97 2. Data fusion, to link travel times with the causal factor (such as weather or incident)
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98 historical conditions, and details three techniques for constructing route-level travel time distributions. The central outcome of this experiment is the comparison of time-ofday travel time distributions along the route constructed using each of the three techniques.
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99 techniques for creating time–space contour plots based on probe speeds. These contour plots can be made to represent any measured speed percentile, so that contours for the worst observed conditions can be compared with typical conditions.
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100 Use Cases A functioning reliability monitoring system must meet the needs of many types of users because different users perceive and value deviations from the expected travel time in different ways. Each user class has different motivations for monitoring travel time reliability, and these needs have to be accounted for in the types of analysis that the system can support through the user interface.
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101 transit systems, and freight systems. Each of these four groups is further subdivided into providers (supply)
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