Automated traffic signal performance measures (ATSPMs) are revolutionizing the way agency engineers view traffic management. These high-resolution data analytic tools pull from systems and components transportation agencies already have in place to improve the movement of traffic and address safety concerns along key corridors.
ATSPMs are even more powerful when they’re deployed across many facilities within a given agency. With large-scale deployment, forward-thinking network management becomes possible within a given agency’s territory.
In the first article of this series on ATSPMs, we provided an overview of how ATSPMs work. In this article, we’ll describe how agencies can set themselves up to deploy ATSPMs at scale. The scalability of ATSPMs is not an all-or-nothing scenario – agencies can take incremental steps to eventually reach large-scale, and even statewide, deployment.
The biggest challenge facing the agencies that we work with is knowing what components are needed to set up ATSPMs for scalability in their specific system. With the right building blocks in place, it is very possible to expand ATSPM deployment gradually.
The Building Blocks of Scalable ATSPMs
Intersection control has evolved in the past hundred years from a police officer standing in the roadway and manually directing traffic to algorithms controlling device networks. Evolving technology has allowed agencies to control intersections remotely and trust that signal system equipment will serve as a proxy for managing traffic demands.
As demands and technologies change, the need for additional control strategies grows. Traffic signal coordination connects a series of signalized intersections to manage vehicle progression along a corridor. Advanced applications such as transit signal priority and adaptive signal control leverage algorithms to adjust signal timing parameters, improving mobility for specific users. ATSPM, which in some ways is the next evolution of intersection control, can use existing infrastructure to shed light on an agency’s traffic signal system by synthesizing data that are already available.
Reliable communication and detection form the foundation of any traffic signal system. Both are needed to foster public trust in a system’s effectiveness and both are vitally important for large-scale ATSPM deployment.
Digitally Reproduced by the USC Digital Archive (c) 2004, California Historical Society, CHS-36733
Communication for Data Reliability
A robust communication network with adequate speed and bandwidth is needed for a traffic signal operator is to be able to access data remotely and trust its reliability. Existing communication infrastructure at intersections, however, can vary. Some agencies rely on older infrastructure that may not be up to the task. In some rural areas, agencies sometimes don’t have the necessary infrastructure at all. The more an agency has set itself up with fiber or advanced communication, the easier large-scale ATSPM deployment will be.
Detection: Know if Your System is Working
Detection systems monitor and log when vehicles arrive at an intersection. Properly functioning sensors allow traffic signal operators to take advantage of their signal controllers’ capabilities. Collected data makes it possible to know the level of demand at the intersection, further increasing opportunities to improve efficiency. However, if a sensor is broken, operations can quickly become inefficient, rendering any type of assessment incomplete. having fully functional detection sensors is critical for maintaining effective and efficient operations and ensuring that data used for performance evaluations is reliable. ATSPM reporting capabilities are as robust as the network’s capabilities to sense its environment through detection.
The components of a signal system are like a pyramid with communication and detection as the base. ATSPM encapsulates traffic signal management and operations by leveraging the communication and detection systems. Graphic by Darcy Bullock of Purdue University and Jim Sturdevant of Indiana Department of Transportation.
Not All Controllers are Created Equal
With detection and reliable communication in place, agencies may also rethink how they are migrating their traffic controller technologies to support ATSPM scalability. Many agencies have older intersection controllers, which are limited in their processing speeds and data storage capabilities. Upgrading to advanced traffic controllers (ATCs) allows for the higher data resolution that makes ATSPMs so valuable. Without the ability to process high-resolution, tenth-of-a-second data, the reporting may not be as useful. In many cases, it may not even be feasible. Agencies with older controllers should plan and budget for new controller technology with ATSPM deployment.
Some agencies have established vendor relationships to meet their evolving controller needs. Pre-negotiated rates, approved vendor lists, or bulk purchases can make the gradual scaling of your ATSPM deployment more cost-effective. Agencies can also explore what work their controller vendors have done with ATSPMs in other areas and inquire about ATSPM readiness. It’s important to note that each vendor may handle data differently.
Identify Your Agency Champion
The organization itself plays a key role in the scalability of ATSPMs. In addition to staff’s ability to access and monitor the system, an agency needs policy champions. These policy champions work with local government and the public to advocate for the value that ATSPMs bring to performance management. They promote ATSPMs as a key differentiator in traffic operations and a pathway to more cost-effective system maintenance. Policy champions can also advocate for change in other areas, like open performance dashboards, which hold the agency accountable to the public and fully leverage the benefit of their data. When looking to bring ATSPMs on a larger scale to your agency, find your policy champion.
Whether an individual or a team, it takes people who understand and believe in the opportunity and value of ATSPMs to carry them forward.
So, what does my system need?
From controllers to communication to data storage, every piece of an ATSPM system has many options, and it’s important to understand how they are working together and working with the existing system. There is more than one “recipe” for successful and scalable ATSPMs, and each transportation agency needs to decipher which pieces will work best with the infrastructure they already have in place.
We recommend that agencies set themselves up for success by developing a standard, or what we refer to as an architecture, for ATSPMs at their intersections, and that agencies plan ahead at a programmatic level. If an agency can get this architecture right and standardize it, it becomes much simpler to deploy ATSPMs in scale.
As consultants, one of the roles we play for agencies is that we help to assess their existing systems and how the pieces are working together, and what tweaks or additions are needed to get to a larger scale deployment without reinventing the wheel – essentially setting up an architecture customized to their system.
Case Study: Virginia Department of Transportation’s Statewide ATSPM Deployment
Virginia Department of Transportation (VDOT) looked to Kittelson to weigh in on what the future could hold for them with ATSPMs. VDOT knew that they needed to lay the foundation for ATSPMs with the right building blocks (shown in the pyramid graphic above) in place and they were ready to advance from a pilot program to full ATSPM deployment statewide.
As part of our work with VDOT, we’ve examined the components of ATSPMs within the context of their specific system and added in each piece in volume to set them up for a successful outcome. For example, we studied various scenarios for loading the data onto their network for the purpose of determining if the existing network could handle the data or would need to be rethought. Essentially, we are thinking through how to develop each of the components to handle more data, which helps VDOT understand the best way to invest.
In addition to determining the needed components of scalable ATSPMs, consultants can bring value to agencies like VDOT by serving as liaisons for their IT network staff. While a firm like ours traditionally works with the traffic engineering side of an agency, working with the technology involved with ATSPMs also means regular interfacing with IT. It’s important to partner with IT staff and champion their IT network priorities while layering on the advanced applications of ATSPM for a successful outcome.
Step by step, VDOT is moving toward large-scale deployment.
Next Topic in ATSPMs: Performance Management
In the third article of this series, we’re going to talk more about performance management – what can you actually do with the ATSPM data you collect?
ATSPMs can bring tremendous value to transportation agencies, and we’re excited to continue pushing forward in this area. Don’t hesitate to reach out to discuss this topic further!