Adaptive Traffic Control Systems: Domestic and Foreign State of Practice (2010) / Chapter Skim
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Pages 10-16
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From page 10... ...
Some agencies are looking for a traffic control system that will be able to handle high day-to-day variations in traffic. For other agencies the primary reason for installing an ATCS may be the reduction in costs to retime signal timings every 3 to 5 years, which may be necessary owing to the steady increase in traffic demand and changes in traveler's patterns.
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From page 11... ...
Surprisingly, if only a single factor with the highest rank for each ATCS deployment is considered then results show that such a system was most frequently deployed because: • The agency served as a testing facility/early deployer of an innovative signal control method -- seven ATCS deployments. • It was recognized that an ATCS would help to resolve conflicts between vehicular traffic and other modes (pedestrian, transit, etc.)
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From page 12... ...
One particular agency (LA DOT) decided to further enhance its Urban Traffic Control System, which resulted in the development of its own ATCS platform.
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From page 13... ...
13 Adaptive Traffic Control System Deployments Figure 2 shows the percentages of the ATCSs deployed by the responding agencies; it is noticeable that SCOOT and SCATS are still the most dominant. However, these results are correlated to the maturity of the systems and their presence on the market.
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From page 14... ...
The following are examples of the agencies' responses: • Insufficient staff and funding to operate and maintain; • Poor communications between vendor and client; • Not cost-effective if volume fluctuations are insignificant or where cycle lengths and splits are quite constrained to meet operational objectives; • Because it is very expensive for the licensing fees and very sophisticated to set up and fine tune. In addition, it 14 requires much vehicle detection that is well-maintained and working properly; • Difficult to program and data intensive; • High cost of supplying communications or low priority sites; and • Only use it at times of high traffic flows as standard vehicle actuation is more reactive at quieter times when linking becomes less important.
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From page 15... ...
15 0 1 2 3 4 5 6 Engineers Timing technicians Field technicians Maintenance technicians Others Staff category N um be r o f s ta ff Average Median Mode (a) y = 0.1973x0.6708 R2 = 0.6527 0 10 20 30 40 50 60 0 500 1000 25001500 30002000 4000 50003500 4500 Number of signals N um be r o f s ta ff (b)
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From page 16... ...
In general, agencies deploy ATCSs in operational environments where ATCSs are known to provide the best performance. For most of the agencies, traffic signals under an ATCS contribute from 10% to 30% of the 16 overall signal population under their jurisdictions.
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