ATSPM is Reducing Traffic and Saving Drivers $2.2 Million a Year

ATSPM is Reducing Traffic and Saving Drivers $2.2 Million a Year
Posted on 04/30/2019
By Council Member Scott Bracken

In 2008, our city engineer had a great idea on how to make traveling along Fort Union Blvd (and other arterials in the city – Union Park, 1300 East, Highland Drive) a lot more efficient. The goal was to reduce local emissions and improve air quality by getting people to where they need to be more quickly and effectively through and around our major intersections.

The concept of Automated Traffic Signal Performance Measures (ATSPM) came to mind. ATSPM involves adjusting traffic signal performance at intersections to the traffic flows, using real time data rather than simply setting a timing cycle. The process had potential to save us all some time, money and stress as we drove around the city. The end result (just in case you want the spoiler without all the detail) is that the system is up and working and is now saving vehicle users collectively about $2.2 million per year. Transit times on our main corridors have been reduced in aggregate by 3 minutes per complete trip.

The city made application to the Wasatch Front Regional Council (WFRC) to use Congestion Mitigation and Air Quality (CMAQ) funds and received the go-ahead to put a project together. During that planning phase, the Utah Department of Transportation (UDOT) became a partner in the planning and implementation as the core concepts had statewide application. The final agreement with UDOT was that Cottonwood Heights would be the first city to have equipment installed to provide real time data to help improve traffic. Data is collected every tenth of a second. Anytime we can aid in improving air quality, save money and make things better is a win in my book so I supported the project from the beginning.

There were three phases to the initial study/project: The “before” phase was April 1 to May 31, 2017, when five intersections had equipment to provide some baseline data. The “intermediate” phase was Sept. 23 through Nov. 23, 2017. Equipment was installed and running at 19 intersections and adjustments to a few key timing points could be made as the system was being fully integrated. The “after” phase ran from March 22 through May 23, 2018, where data was analyzed and some final tweaks could be made with coordination and synchronization schemes.

Some key findings of the study are as follows:
• As previously stated, aggregate travel time was reduced by 3 minutes across the four corridors, amounting to user benefits of about $2.2 million annually;
• The split-failure rate (i.e., how often vehicles had to wait more than one full cycle to clear an intersection) decreased by 35 percent in the intermediate phase, and another 4.5 percent in the after phase. Remember that this is data aggregated across the city. There were a few specific times of day when split failures went up at a single intersection, but overall there was a significant reduction in vehicles having to wait multiple cycles to get through an intersection;
• Overall, there was a 6 percent increase in vehicles that arrived on a green light and didn’t need to wait at all. While this may seem to be a small increase, in my experience the impact is still significant as it eliminates all the start-up/acceleration noise and extra fuel needed to get your car back up to travel speed.

One additional benefit of having all the ATSPM equipment up and running should be realized once the intersection of Fort Union/Highland Drive construction project is completed (slated for late June) with double left turn lanes in each direction and additional dedicated right turn lanes. Rather than having to wait to complete the project, conduct a thorough traffic study for a few weeks, and then analyze the data to figure out how to best coordinate the new traffic flows with all the other intersections in town, with the new systems in place, the data collection is instantaneous and analysis can begin immediately. Furthermore, it can be continuously looked at as part of a whole system in the city and not just an isolated intersection. Other cities in the county (and I assume the state) are already bidding out upgrades to their intersection equipment to take advantage of UDOT’s new core capabilities.

This project took a long time from genesis to fruition. But it is creative ideas and inter-governmental cooperation on projects like this that demonstrate good governance and honest public service, resulting in an increase to general welfare. Our city has a rich history of inter-governmental cooperation with the state, county, Canyons School District, the Cottonwood Heights Parks & Recreation Service Area, neighboring cities, and many other agencies. By working together, we can achieve great things, all while keeping governance as close to the people as possible.