Adaptive Traffic Control Systems: Domestic and Foreign State of Practice (2010)

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47 The study findings were based on a literature review and two electronic surveys: a shorter e-mail survey for vendors or devel- opers of 10 major adaptive traffic control systems (ATCSs) and a main website-based questionnaire for agencies that deploy ATCSs. The main survey was originally distributed to 42 agencies that run ATCSs in North America (United States and Canada) and several dozen locations around the world. Numerous follow-up requests were made, by e-mail and phone, to remind agencies that had not yet responded, asking them to participate in the survey. Responses were obtained from 34 of 42 agencies in North America, an 81% response rate. Also, 11 responses were received from agencies in other countries. Of the North American agencies, 42% were munici- pal entities, 20% were counties, 13% were state agencies, and 25% were other. The survey indicated that ATCS agencies deploy their ATCSs in operational environments where the systems are known to provide the best performance. Most of those inter- viewed have 10% to 30% of their traffic signals under the ATCS. Handling daily and weekly fluctuations in traffic flows is the highest ranked reason for ATCS deployments. When procuring an ATCS, agencies frequently consider multiple sys- tems. On average, an ATCS installation takes approximately 18 months, from the time when funding is made available to the time an ATCS becomes fully operational. Most of the ATCSs that have been deployed during the last 20 years are still in operation. If an ATCS is shut down it is usually the result of several negative factors. Agencies frequently expand their ATCSs and, in general, most are satisfied with their operations. Review of the most widely used ATCSs showed that var- ious systems use similar strategies to cope with fluctuations in traffic demand and distribution. However, each tool is unique and without direct comparison it is difficult to com- pare the algorithms and adaptive logic of the various tools. Field implementations of various tools are even more unique than their logics, which makes direct field evaluations expen- sive and therefore impractical. For this reason, among others, very few studies in the literature provide evidence that the operational concepts of one particular ATCS are better than those of another. There is a considerable need for expertise to ensure a successful ATCS implementation. Although many agencies implement ATCSs to reduce labor-intensive maintenance of signal timing plans, survey respondents indicated that ATCSs are only tools for traffic management and they need to be supervised and controlled by skilled engineering staff. Proper training and acquisition and retention of expertise within an agency were reported as the most important factors for allevi- ating institutional barriers for ATCS deployment. ATCS opera- tions are often not perceived as being difficult; however, it appears that ATCS users are not often given the opportunity to learn how to fully operate their systems. One of the reported operational problems indicated a lack of the basic knowledge for operating an ATCS. A majority of the ATCS users rely on in-house expertise, which is more an indication of not having adequate resources to hire outside support than that ATCS users are fully trained to control and operate their systems. In general, ATCS users would like to acquire additional expertise; however, the agencies do not have enough financial resources to acquire comprehensive training, and most of the agencies are short staffed. ATCSs are considered more operationally demanding than conventional traffic signal systems; however, agencies are not able to support these systems in the same way they support conventional traffic signal systems. Unlike con- ventional systems that are maintenance-intensive, ATCSs require more emphasis on the expertise necessary to operate their sophisticated operations. This switch in the type of labor (from maintenance to operations), which is needed to support proper ATCS operations, is often not recognized by an agency until the ATCS is already deployed. This inability to recognize the need for additional operational expertise in a timely man- ner can adversely affect the ATCS performance. If the agency is disappointed with the performance, it will be reluctant to expand on the existing system or to procure new ATCSs. Detection requirements for an ATCS are slightly higher than those for conventional traffic-actuated control systems. Most of the ATCS users are satisfied with the way their system handles minor detector malfunctions. Some ATCS users have difficulties with the handling of ATCS-specific hardware, although this is primarily an issue that could be resolved with better training of the technical staff. ATCSs mainly operate on Windows-based platforms and are sometimes integrated with one of the available Advanced Traffic Management Systems (ATMSs). Integration with an ATMS, which is not common, has become more frequent with recent ATCS implementa- tions. As perceived by most of the users, ATCS software is one of the components that need improvement. Interestingly, ATCS users do not find that ATCS communications cause CHAPTER EIGHT CONCLUSIONS

many more problems than the communications of conven- tional traffic control systems. However, communications play a much more important role in ATCS deployments and for this reason need to be regularly maintained, which represents one of the major operational costs for ATCS users. The survey results showed that ATCS installation costs per intersection are approximately $65,000 and are higher than previously reported. Interestingly, results showed that ATCSs require less funding for physical maintenance than conventional traffic signals. This finding contradicts com- mon belief present in the traffic signal community that main- tenance of ATCS detectors and communications is costly. When ATCSs are evaluated most agencies prefer to hire outside consultants, which primarily perform field evalua- tions through a set of before-and-after studies. A majority of the user evaluations reported that ATCSs outperformed con- ventional traffic signal systems. The benefits of ATCS deployments are not easily observ- able in oversaturated traffic conditions. Although ATCS users find that their systems may delay the start of oversatu- ration and reduce its duration, they are not recognized as a cure-all for such traffic conditions. However, modifications of an ATCS to reduce oversaturation is often beyond the competence level of ATCS users; therefore, there is little data available to draw conclusions about ATCSs’ perfor- mances in oversaturation. Most users do not perceive that the performance of their ATCS degrades over time. Public education campaigns about ATCS deployments are not very common and effective, as indicated by most ATCS users. Also, not many ATCS agen- cies conduct public perception surveys. Those agencies that do reported that results from such surveys are supportive approximately 50% of the time. ATCS agencies were mostly generally satisfied by their sys- tems’ ability to provide what was observed as “efficient opera- tions” and to adjust to within-day and day-to-day traffic fluctu- ations. Negatives were mostly related to difficulties in learning how to operate the system and the hardware (primarily com- munications). Lessons learned can be summarized in four cat- egories, which represent pre-deployment actions necessary for successful ATCS implementation: better local support from vendors; better planning for in-house operational and institu- tional support; good preparation of the infrastructure (detection and communications); and detailed pre-installation evaluation to estimate operational benefits. Major reasons that prevent ATCSs from further expansion include the high costs related to operating and maintaining the system (e.g., employing and training the staff). Overall, most of the surveyed ATCS users (73%) would install the same system again. Users with more signals under an ATCS have more satisfactory experiences with ATCS operations. More signals under an ATCS attract more attention within the agency, and therefore more resources to operate and maintain the ATCS, more staff to develop and maintain in-house expertise, and finally more attention from ATCS vendors. Smaller systems are inclined to have more problems securing funding and hence their overall experience with ATCSs is not as positive. Although specific recommendations were not requested in the survey, survey recipients suggested the following research to improve knowledge of ATCS implementations in the United States and other countries. • Explore establishing a coalition for Adaptive Traffic Control, which could serve as a framework for exchang- ing experiences and lessons learned about ATCS deploy- ments. Agencies with smaller budgets for ATCSs may particularly benefit from such a coalition. One of the first priorities could be to investigate factors that represent barriers for new agencies to deploy an ATCS. • Research into funding operations by an ATCS includ- ing the Transportation Pooled Fund Program and other similar programs that could provide resources to con- duct further studies on these systems to address the most important and urgent issues. • More study is needed to estimate the true benefit–cost ratios of ATCS deployments. There is a need for com- prehensive evaluation studies that would show all of the costs and benefits of an ATCS deployment (including investigation of the long-term operational savings result- ing from long-term changes in traffic demand). • ATCS agencies could be encouraged to document and analyze implementation issues (i.e., staff retention) to identify the costs and benefits associated with the use of an ATCS when compared with the deployment of con- ventional traffic control systems. Potentially, these doc- umenting efforts could be a requirement imposed, and financially supported, by federal authorities. Demon- strating benefits can promote more extensive and more appropriate use of ATCSs. • More research is needed to investigate various funding sources used to deploy ATCSs. Research on how much funding is necessary to support various components of ATCS installations [e.g., cost of hardware (electron- ics), software, and labor (installation, maintenance, and operations)] is also needed. It could be also investigated how agencies make decisions to deploy ATCSs and whether decisions are made in coordination with oper- ational staff. 48