Evaluating Alternative Operations Strategies to Improve Travel Time Reliability (2013) / Chapter Skim
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Pages 22-33
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From page 22... ...
22 Given the reliability needs of stakeholders and the ability to manage reliability by agencies, a set of agency goals and performance measures has been identified to improve travel time reliability. This section describes existing data issues and the need for developing goals and performance measures to improve travel time reliability.
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23 be collected on most major freeway systems at a moderate cost if the data are not already available through existing sources. What is unknown is whether roadway agencies will have the discretionary funding to pay for the collection of these data.
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24 Without these data, it is impossible to determine whether changes in roadway performance are due to the actions of the operating agencies or changes outside of the control of those agencies. The data are needed for the following reasons: • To improve roadway agencies' operational decision making in real time; • To support traveler information services; • To determine the causes of unreliable travel in planning time; and • To evaluate the effectiveness of programs implemented to improve travel time reliability.
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25 circumstances, these delays have been minimized as part of the design and implementation of the traffic-control system. In many cases, however, the traffic-control plan works less than optimally, because the control system does not adequately account for variations in the traffic volumes being served at that specific time.
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26 Roadway Performance Measures Performance measures relate to the physical performance of a roadway. These measures consider travel demand and a variety of factors both within and outside of the roadway agency's control.
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27 The last proposed performance measure is of interest mostly to roadway facility managers. Volume (i.e., use)
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28 when travelers must leave home on the way to work, which provides for different levels of exposure to routinely congested time periods. It is unclear at this time whether freight mover reliability should be reported differently from passenger traveler reliability for the same roads.
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29 202, Guide to Benchmarking Operations Performance Measures (Tarnoff et al.
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30 traffic management plans in order to determine the performance of those control plans and the need for any changes. Bottlenecks Specific reporting statistics describing bottlenecks are not recommended in this report.
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31 significant portion of the basic roadway performance (travel time and speed) data.
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32 costs. Therefore, it is important that the performance goals be selected after considering whether the intended outcomes are reasonable.
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33 they do not have the necessary data to establish a baseline. As a result, these agencies are reluctant to set goals without knowing whether they can possibly meet them.
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