Be sure to conduct a detailed evaluation prior to installing an Adaptive Traffic Control System (ATCS), and be aware that conducting a public education campaign on ATCS risks building expectations too high.
Experience acquired from multiple agencies in the United States and Canada.
Date Posted

NCHRP Synthesis 403 Adaptive Traffic Control Systems: Domestic and Foreign State of Practice

Summary Information

A study published in 2010 reported the survey results of agencies with Adaptive Traffic Control Systems (ATCS). The survey results described the benefits and lessons learned acquired by domestic and foreign ATCS agencies in terms of working principles of ATCS, aspects of training, institutional factors, and benefits. Responses were obtained from 34 of 42 agencies in North America (an 81% response rate) and included city agencies and state Departments of Transportation (DOTs) in Arizona, Arkansas, California, Delaware, Florida, Georgia, Michigan, Minnesota, Missouri, North Carolina, Ohio, Oregon, Texas, Utah, Virginia and the state of Washington. Canadian agencies that participated in the survey included the ATCS vendor Econolite Canada and ATCS user agencies from the cities of Halifax, Red Deer and Toronto. International survey participants included ATCS agencies in Ireland, New Zealand, Australia, Chile, the United Kingdom, and China.

Lessons Learned

The following lessons learned provide insight on ways of successfully implementing an ATCS project, and whether conducting a public outreach campaign is likely to be of value.

  • Conduct a pre-installation evaluation to estimate the benefits of an ATCS before deciding to implement the system. When asked what they would do differently in hindsight, ATCS agencies indicated that they would be sure to conduct a detailed pre-installation evaluation. If possible, run operations with traffic signals under actuated coordination to estimate probable benefits. A thorough pre-installation evaluation helps determine whether or not to install an ATCS, which may not be necessary at all if intersections have regularly repetitive traffic conditions, or if a good coordinated actuated control is sufficient to realize improvements. A pre-installation evaluation serves other functions as well, such as allowing an agency to gather the "before" data that is so often lacking but needed in before-and-after studies, identifying the areas that do not require improvements (such as the areas with normal traffic conditions), and determining where the ATCS must be integrated with other applications. Some ATCS agencies reported that they turned off their systems when it was discovered that the ATCS was incompatible with the ramp-metering system.
  • Be aware that conducting an ATCS outreach campaign may not be effective, or can even backfire, because the benefits of an ATCS may not be readily observable to the average traveler. The implementation of major traffic improvements is often accompanied by education campaigns to inform the public of a project's anticipated benefits as well as expected changes in traffic patterns. Such campaigns can facilitate public acceptance, which is often a key factor determining the success of a deployment. However, as indicated by the experience of several ATCS agencies, ATCS benefits may not be observable to the average traveler (particularly in oversaturated traffic conditions). ATCS agencies reported that their campaigns were either ineffective or backfired, resulting in increased complaints from the public. Conducting a public campaign runs the risk of building expectations too high and subsequently disappointing travelers who do not perceive improvements or even experience delays in other areas.
  • Seriously consider installing an ATCS if extensive capital costs for intersection infrastructure are needed. Agencies should consider deploying an ATCS when faced with carrying out capital-intensive upgrades on intersections. ATCSs remain in better shape over longer periods than do conventional traffic control systems. It is an opportune time for an agency to install an ATCS as it works on major intersection projects such as re-configuring intersection geometry, replacing signals, or installing detection systems.
  • Insist on retaining local vendor support from the ATCS vendor, at least for the months immediately following deployment. ATCS users reported that a key factor in successful deployments was retaining local vendor support. Having dedicated support staff in the field meant that issues were addressed as they arose, which is particularly important in the early months of deployment when agency staff have not yet had the time to gain the engineering expertise to tweak (or repair) the system.

Learning from the experiences of ATCS users improves future planning and deployment. By following the recommendations above, as well as others, agencies considering an ATCS will develop and deploy better systems. One effort that may not be needed is for agencies to conduct outreach campaigns on ATCS. ATCSs provide improvements on a system-wide basis, but their benefits may not be readily observable to the public.

System Engineering Elements

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