Automated Traffic Signal Performance Measures

Automated Traffic Signal Performance Measures Before and After Every Day Counts-4

Automated traffic signal performance measures (ATSPM) are fueling a transformation in how transportation agencies approach the management, operations, and maintenance of signalized intersections. The Federal Highway Administration's (FHWA) inclusion of ATSPMs in the fourth round of Every Day Counts (EDC-4) initiative catalyzed the transformation of traffic signal operations from traditional reactive, temporal, and complaint-based approaches to active, objectives- and performance-based approaches. The outcome of shifting traffic signal operations from reactive to proactive results in high-quality traffic signal operations that are consistent with the needs of communities and reflected in operations and maintenance objectives. ATSPMs empower agencies to provide signal operations that are safer, promote greater mobility, reduce congestion, and demonstrate fiscal responsibility.

Deployments and Agency Participation

Prior to EDC-4, the largest catalyst for ATSPM deployment was the American Association of State Highway and Transportation Officials Innovation Initiative led by the Utah Department of Transportation. It resulted in early ATSPM technology implementation by states and local agencies and established a community of peers ready to share implementation experiences. In Fall 2016, regional EDC summits were held to discuss the selected EDC-4 innovations (including ATSPM) and to find opportunities for implementation. After the summits, State Transportation Innovation Councils (STIC), which bring together public and private stakeholders, met to evaluate innovations and set goals for their deployment. STICs are active in all 50 States, the District of Columbia (DC), Puerto Rico, the U.S. Virgin Islands, and Federal Lands Highway. In January 2017, eleven State departments of transportation had implemented ATSPM to either the demonstration, assessment, or institutionalized levels. The remaining 43 states (whose count included Federal Lands Highway, Puerto Rico, U.S. Virgin Islands, and DC) reported ATSPM in the development stage or were not planning to implement.¹

At the conclusion of EDC-4 in December 2018, 31 states had achieved their implementation goals of deploying ATSPM on either the demonstration, assessment, or institutionalized levels. The remaining 23 states reported ATSPM in the development stage or were not planning to implement. While the goal of implementation by at least 35 states was not achieved, it is notable that during this two-year period the percentage of states demonstrating, evaluating, or institutionalizing ATSPM crossed the 50 percent threshold and reached 57 percent by December 2018.

Software Options and Private Sector Products

During the course of EDC-4 implementation, the number of ATSPM solutions have increased significantly. Prior to EDC-4, UDOT developed an opensource ATSPM software solution with the support of FHWA and the private sector. UDOT also hosted workshops to share their experience and support ATSPM implementation by others. As EDC-4 unfolded, the number of private sector ATSPM solutions increased and provided operating agencies with a diverse family of options to support implementation.

In parallel with EDC-4, FHWA has also worked to provide other opportunities for support to operating agencies. This includes hosting the latest versions of the ATSPM open source code on the GitHub software platform. FHWA has also worked to foster a community of ATSPM users and developers by hosting regular User Development Forum webinars that provide a venue for developers to provide updates on code enhancements and for users to learn from the deployment experience of their peers.

Private sector products featuring ATSPM capabilities have surged during the time-frame of EDC-4 implementation from four to 14. The largest growth in private sector ATSPM adoption has been the result of traffic signal equipment manufacturers including ATSPM capabilities into their traffic signal management software. Third-party data solutions companies have also entered the mix with vendor-agnostic platforms that can integrate with existing systems regardless of controller manufacturer. Most third-party options provide a subscription-based solution that hosts an agency's ATSPM data in the cloud. Agencies without large in-house information technology resources may find cloud-based ATSPM solutions easier to implement since most of the administration and storage is handled off-site by the third-party provider.

Guidance

Several lessons learned were identified by FHWA during the EDC-4 implementation initiative.

• Technology alone cannot solve every problem with a traffic signal system. As part of outreach activities, care was made to present ATSPM as one component of an objectives- and performance-based traffic signal program. In spite of that effort, some agencies continue to view ATSPM as an automatic "quick fix" to traffic signal timing issues. Instead, for ATSPM to be effective, agencies should change their business process and staffing to encourage traffic signal optimization based on data-oriented triggers. Eddie Curtis, traffic operations specialist with the FHWA Office of Operations, likens ATSPM to the tire pressure light on a car dashboard. "The tire pressure light is a great thing, since it tells you when your pressure is low. However, it doesn't put the air in your tires for you—that's something you as a driver must do." In the same way, ATSPMs can serve as a warning light for traffic signal system issues. However, there should be a process in place for traffic engineers and technicians to take action based on the information they receive. ATSPMs by themselves will not improve traffic flow. However, ATSPMs give traffic engineers and technicians a much clearer picture of traffic system and intersection performance. This information allows them to find and address issues faster than was possible in the past. Good information together with taking proper action can lead to improved traffic operations.
• A more comprehensive approach to local engagement could address under-reporting of ATSPM implementation. EDC-4 implementation goals for ATSPM were defined as state-level goals through coordination between FHWA and each State DOT. Implementation progress was tracked though information provided by State departments of transportation (DOT) to their local FHWA Division Office. Because of this, FHWA typically has good visibility into ATSPM initiatives conducted at the State level. However, the situation is more complicated in States with large numbers of local maintaining agencies. In some cases, implementation by local agencies may not be reported to the FHWA Division Office, so the status of implementation in the State may be under-reported. In other cases, a local agency may have a greater interest in ATSPM implementation than the State DOT. A State DOT may have established a "no implementation" goal, while at the same time a local maintaining agency may be operating a very mature ATSPM deployment. This State would not receive credit for implementation even though the state of the practice was being advanced. Because of these issues, a more comprehensive approach would be helpful in engagement with local maintaining agencies to avoid under-reporting of ATSPM implementation.