Incorporating Reliability Performance Measures into the Transportation Planning and Programming Processes: Technical Reference (2014) / Chapter Skim
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Pages 152-161
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From page 152... ...
151 Agencies can use five broad categories of traffic data sources to monitor travel time reliability: 1. Infrastructure-based detectors that can sense volume, occupancy, speed, and other data; 2.
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152 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE some processing and extrapolation before travel times can be calculated. This also means that the accuracy of the travel time measures they produce is a function of how frequently detectors are spaced along the roadway.
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153 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE detection zones on a computer that are in the field of view of each camera, meaning that it is important that the cameras not be moved and the detection zones be set up correctly. Some specialized systems can also re-identify vehicles detected at two separate cameras, giving them AVI capabilities.
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154 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE This technology is advantageous in that it is accurate, low-cost, and portable. A drawback, however, is that currently only a small percentage of drivers have Bluetooth-enabled devices in their vehicles; recent (2010)
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155 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE As a result, in Orlando, toll tag readers usually only generated between 10 and 20 travel time estimates per hour. Agencies should thoroughly evaluate their regional saturation rate of RFID toll tags to determine whether this technology can supply the number of travel time samples needed to robustly estimate reliability measures over time.
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156 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE accurately represent travel time variations. However, it can be reasonably assumed that more vehicles and devices will have GPS capabilities in the future.
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157 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE E.4 PRIVATE-SECTOR–BASED SOURCES In addition to the public sector sources described previously, private sources of data can be used to support reliability analysis. SHRP 2 Project L02 conducted a series of focus group interviews on data collection practices and business processes related to measuring, monitoring, and recording travel time reliability information.
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158 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE and ubiquitous smart phones, this is rapidly changing. Currently, an estimated 35% of drivers have smart phones, many of whom use the device's GPS capabilities invehicle for navigation assistance.
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159 INCORPORATING RELIABILITY PERFORMANCE MEASURES INTO THE TRANSPORTATION PLANNING AND PROGRAMMING PROCESSES: TECHNICAL REFERENCE happening by saving operator actions time stamps. These time stamps can be used to determine the time the lanes were closed for an incident, the agency response time, and what time the lanes were cleared.
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