National Academies Press: OpenBook

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

Chapter: Chapter Seven - Lessons Learned

« Previous: Chapter Six - Implementation Costs and Benefits
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Suggested Citation:"Chapter Seven - Lessons Learned." National Academies of Sciences, Engineering, and Medicine. 2010. Adaptive Traffic Control Systems: Domestic and Foreign State of Practice. Washington, DC: The National Academies Press. doi: 10.17226/14364.
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Page 43
Page 44
Suggested Citation:"Chapter Seven - Lessons Learned." National Academies of Sciences, Engineering, and Medicine. 2010. Adaptive Traffic Control Systems: Domestic and Foreign State of Practice. Washington, DC: The National Academies Press. doi: 10.17226/14364.
×
Page 44
Page 45
Suggested Citation:"Chapter Seven - Lessons Learned." National Academies of Sciences, Engineering, and Medicine. 2010. Adaptive Traffic Control Systems: Domestic and Foreign State of Practice. Washington, DC: The National Academies Press. doi: 10.17226/14364.
×
Page 45
Page 46
Suggested Citation:"Chapter Seven - Lessons Learned." National Academies of Sciences, Engineering, and Medicine. 2010. Adaptive Traffic Control Systems: Domestic and Foreign State of Practice. Washington, DC: The National Academies Press. doi: 10.17226/14364.
×
Page 46

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43 INTRODUCTION Each deployment can be different and challenging both to the vendor who installs the ATCS and the agency that operates and maintains the system. Each deployment process is also a learning experience from which agencies can determine what could have been done differently. This chapter identifies major lessons learned through a series of questions answered by interviewed ATCS users. First, ATCS users’ positive and negative surprises from ATCS deployments were noted and then the agencies provided their hindsight perspectives. Sub- sequent sections also present factors that caused several ATCS shutdowns, problems that prevent further ATCS expansions, and the potential for future ATCS deployments. USER PERSPECTIVES Positive and Negative Surprises from Adaptive Traffic Control Systems Deployments The deployment of an ATCS is a challenging process for both ATCS users and the vendors and consultants who per- form system installation and integration. No two ATCS deployments are the same. Idiosyncratic characteristics of deployment site, traffic conditions, an agency’s legacy hard- ware and software, and the institutional and cultural charac- teristics of the agency, make each ATCS deployment unique. For this reason each new ATCS deployment represents a new learning experience both for the agency and the vendor. Although there is significant literature on ATCSs, people who have not worked with an ATCS before tend to get a skewed picture about its abilities. This picture is sometimes intentionally skewed by ATCS vendors who are trying to sell intellectual properties and consulting services for an ATCS to as many customers as possible. From that perspective, it is interesting to discover what operational surprises are noticed by agencies during their deployments. The following list shows examples of positive and negative surprises. • Positive – How well it responded to changing traffic conditions – Short system response time to fluctuating demands – Effectiveness of the system – Does adapt to daily commuter traffic – How well it worked; traffic data stored – Moving special events traffic efficiently – Better than expected results in before-and-after study – It worked with NEMA controllers and cabinets – System is very flexible – Side street venue dumps were dramatically improved – Centralized control, performance measures – Successful possible signal coordinating – Spillback on Interstate reduced – Good early learning opportunities for ATCS – Appeared to handle delays about as well as promised. • Negative – Black box—difficult to explain signal operation – Video detection system a high maintenance effort – Had hardware issue with communications, but it was resolved – Lots of effort required to keep optimal performance – Steep learning curve – System difficulty and lack of support – Hardware was discontinued by manufacturer – Much more sophisticated and complicated than told – Initial set-up costs and time taken – Amount of time needed for deployment – Time and effort to debug central and field equipment – Importance of communications – Some phases not being served in early deployment – Design consultant made mistakes – There was a recurring issue with phase skipping. People were mostly pleasantly surprised by ATCS’s abil- ities to provide what was observed as “efficient operations” and to adjust to within-day and day-to-day traffic fluctua- tions. The second important positive surprise related to a systems ability to store traffic data that previously required much more difficult data collection efforts. Negative surprises were mostly related to difficulties in learning how to operate the system and hardware issues (mostly communications). There were also some complaints about operational features of the systems (e.g., phases being skipped), which reflect a lack of hands-on expertise within the agency, availability of local technical support, or problems with hardware more than deficiencies in operational philosophies of their ATCSs. There is a notion that some ATCS users jumped into installing an ATCS to replace an outdated fixed-time or iso- lated traffic signal system. In such cases, the agencies won- dered if the same operational benefits, which are achieved with the ATCS, could be achieved with conventional actuated- coordinated traffic control. CHAPTER SEVEN LESSONS LEARNED

Hindsight Perspectives To summarize what agencies have learned through their ATCS deployment processes we asked them to answer what they would, in hindsight, have done differently during the implementation of their ATCSs. Most of the responses indi- cated that greater emphasis might be given to local support, either through acquiring more in-house knowledge or by ascertaining that technical support for their ATCS is avail- able locally. Better planning and preparation of the necessary infrastructure (communications and detection) are the next important issues that most agencies would have done differ- ently. Finally, some agencies recognized that they would need more information on the costs and benefits associated with installation of ATCS. The following is a list of the actions, summarized in four major categories, which the interviewed ATCS users would have done, in hindsight, for their ATCS implementations. • Secure good local support from the vendor by – Asking for dedicated support field staff; insisting on local vendor support – Spending more time with the vendor’s engineer(s) – Keeping a more watchful eye on the contractor install- ing the system; design consultant had no expertise in ATCS. Vendor, at first, did not supply the people with the most expertise—so the design consultant made mistakes that had to be changed post-installation – Waiting for vendor-supported product rather then deployed test application. • Improve the planning process to avoid in-house opera- tional and institutional issues by – Starting with a larger region – Allocating more time for debugging – Getting buy-in from operational staff and not just the steering committee and project management – Involving local staff at a much earlier stage and achiev- ing full independence and expertise earlier as a result – Doing it all in-house from the start – Appointing the necessary expertise to manage the network. • Prepare infrastructure (e.g., detection and communica- tions) for an ATCS deployment by – Replacing all existing equipment—not retrofitting – Using conventional loop detection or established non- intrusive detection rather than the first release of a new model of video detection – Testing (thoroughly) local control firmware and ease of use for technicians – Reviewing and planning for better communications; adding CCTVs for monitoring – Waiting for more current algorithms to be developed before deployment; putting more thought into detec- tor placement – Using inductive loop detection exclusively; micro- wave detection was used for about half of the links 44 to reduce installation costs—they turned out to be extremely unreliable – Using 170 controllers, installing new communications (fiber or twist pair) everywhere (tried to use existing old twisted pair), starting smaller and then expand out. • Conduct a detailed pre-installation evaluation to esti- mate the operational benefits of an ATCS before decid- ing to implement an ATCS by – Gathering more before-and-after data – Not deploying an ATCS at areas with normal traffic conditions – Running the operations with traffic signals under actuated coordination before deploying an ATCS. Factors That Caused System Shutdowns Lessons learned might also include instances where ATCSs were turned off. Although the few agencies that turned off their ATCSs did not provide specific details to justify their decisions, the following is a list of major factors that influ- enced those decisions: • Improper detection layout and other operational prob- lems; • Multiple simultaneous events: budget reductions, staff reassignments, construction projects (resulting in sig- nificant removal of system detection); • Operational problems; agency did not shut down the entire system, but it turned most of the ATCS signals to actuated-coordinated operations; • System incompatibility with ramp-metering where inte- gration of arterial and ramp operations was required; and • No operational benefits achieved; problems with hard- ware and software. Problems Preventing Expansion of Adaptive Traffic Control System The results from the survey indicated that the high cost of ATCS deployments is the most prohibitive factor to expanding current ATCSs (50% of the cases). The second factor, by importance, is the lack of traffic signal operations staff—a problem that can also be attributed to inadequate funding. Finally, some agencies reported that the operational ineffi- ciency of their ATCSs is the major reasons they have not expanded their systems. The following is a list of the major rea- sons that interviewed ATCS agencies were prevented from expanding their systems spatially (to neighboring intersections) and temporally (to be used 24 hours a day/7 days a week): • 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 too constrained to meet operational objectives;

45 • Costs of licensing fees and the highly sophisticated expertise needed to set up and fine-tune the system. In addition, it requires lots of 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. Future Adaptive Traffic Control System Deployments Approximately 73% of the ATCS users interviewed would install the same system again. The remaining 27% of the ATCS users, who would not install the same ATCS, indi- cated various reasons for such a decision. The single greatest problem is the high cost of operating and maintaining an ATCS. Other problems, as shown in Figure 17, included high installation costs and a lack of expertise within an agency. Also, ATCS users found, with an approximately equal level of importance, that they did not achieve the expected benefits from their systems and that technical support is weak. Only 5% of the interviewed agencies would not install the same ATCS because they are convinced that other ATCSs work better. Interestingly, when results from Figure 4 and Figure 17 are compared, it can be noted that 79% are satisfied with their systems, but only 73% would install the same systems again. This difference in the results can be explained with combi- nations of the factors against another ATCS deployment, which are shown in Figure 17. To determine whether there is any relationship between the size of an ATCS and user satisfaction of the agency that runs the ATCS, responses on the question from Figure 17 were divided into two categories. One category represented large ATCS deployments with 50 or more intersections under an ATCS and the other category included all other ATCS deployments. The findings showed that approximately 90% of the users with large ATCS deployments would install their systems again versus only 47% of users of small ATCSs. The findings imply that users with more intersections under an ATCS have a better experience with their ATCSs. The better experience is most likely the result of more resources that are available to these agencies to operate and maintain ATCSs, more staff to develop and maintain in-house expertise, and more attention being given by ATCS vendors. SUMMARY This chapter identified lessons learned by ATCS users from various perspectives such as deployment surprises, hind- sight opinions, factors that influenced ATCS turn-offs, rea- sons preventing ATCS expansions, and potential for new ATCS deployments. ATCS agencies were mostly pleasantly surprised by the system’s abilities to provide what was Yes, we would probably install the same ATCS again; 30; 57% No, other ATCSs seem to work better; 2; 4% No, installation costs are too high; 3; 6% No, operations and maintenance costs are too high; 6; 11% No, we do not have enough expertise within the agency; 4; 8% No, technical support from vendor is weak; 2; 4% No, ATCS deployment is not necessary – we did not see expected benefits; 2; 4% No, for other reasons; 3; 6% FIGURE 17 Deploying an ATCS again. Would you install the same ATCS in another location?

observed as efficient operations and to adjust to within-day and day-to-day traffic fluctuations. Negatives were mostly related to difficulties in learning how to operate the system and hardware issues (mostly communications). Lessons learned can be summarized in four categories: (1) better local support from the vendors; (2) better planning for in- house support; (3) a good preparation of the infrastructure (detection and communications); and (4) detailed pre-instal- lation evaluation to estimate operational benefits. When an ATCS was turned off it was done for a variety of reasons; with low operational benefits being one of the major rea- sons. A major reason preventing ATCSs from further expan- sions are the high costs related to operating and maintaining 46 an ATCS (e.g., employing and training the staff). Overall, most ATCS users (73%) would install the same system again. This number increases when larger ATCS deploy- ments are considered. Smaller systems tend to have more problems in securing funding and therefore their overall experience with an ATCS is not as positive. Major draw- backs for those agencies that would not install the ATCSs again are the high costs of operating and maintaining an ATCS (where the emphasis is given to operations and engi- neering and not physical maintenance), weak (local) techni- cal support, and that the benefits of running an ATCS are not always clearly expressed. The next chapter provides the conclusions drawn from the study.

Next: Chapter Eight - Conclusions »
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TRB’s National Cooperative Highway Research Program (NCHRP) Synthesis 403: Adaptive Traffic Control Systems: Domestic and Foreign State of Practice explores the state of practice of adaptive traffic control systems (ATCSs), also known as real-time traffic control systems, which adjust, in real time, signal timings based on traffic conditions, demand, and system capacity.

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