Dan Martell, regional traffic engineer for the South Dakota Department of Transportation, said the system's engineering process is finished, which determined it is a viable option for the city. The next step, he said, is seeking requests for proposals from companies to evaluate the cost and functionality.
Public Works Director Robin Bobzien said the 15 traffic signals along Sixth Avenue are now governed with a master controller.
"It's far better than when they were all independent," he said.
Martell said the signals are programmed based on traffic patterns for particular times of the day. That means the length of the lights varies based on known traffic patterns.
An adaptive system would continually adjust the length of signals using real-time data by keeping track of the number of vehicles on the street and the wait time at intersections. It would also monitor how far traffic backs up in an area if, for example, a train was crossing at South Fifth Street.
Martell said estimated cost for the work has yet to be determined, but bidding should be in fiscal year 2019 with installation likely in the summer. Federal and state safety funding will cover the cost.
He said the adaptive system could use cameras to detect and count vehicles or sensors that would be installed in the pavement. There will be some disruption for drivers during installation, Martell said. The extent will depend on the amount of infrastructure that's needed, including pavement sensors or fiber-optic cables.
The cameras would only collect data on vehicle numbers and patterns, he said. They would not record video. The traffic data, he said, would help determine if the system is adjusted properly.
Sioux Falls has adaptive traffic signals in three areas. Aberdeen would be the second city in South Dakota to try them.
Heath Hoftiezer, principal traffic engineer for Sioux Falls, said adaptive systems are installed along East 26th Street, 41st Street and South Louise Avenue near The Empire Mall. While the systems on 41st Street and South Louise Avenue were installed in 2017, the one on 26th Street has been in place longer. In addition to reducing commute time, Hoftiezer said, one surprising benefit has been a reduction in crashes.
The 41st Street system covered 13 intersections at a cost of $528,056. The system spanning eight intersections on Minnesota Avenue cost $332,754.
"The way the system works, once the traffic is slowing intersection to intersection, you're less likely to have collisions," Hoftiezer said.
According to the data collected along 26th Street, he said, there was a 21 percent reduction in crashes. Prior to the adaptive signals there were an average of one crash every three days. Now, he said, there's an average of one every four days.
Hoftiezer said one thing drivers might immediately notice is less predictability with the timing of the signal and when the protected left turn arrow appears.
"The system optimizes it on when the left turn works best," he said.
A signal might also go through a quick cycle if there's a vehicle or two waiting on a side street.
Hoftiezer said corridors like Sixth Avenue in Aberdeen are ideal for adaptive systems because there's irregular spacing between traffic lights.
In Sioux Falls, he said, traffic flow improvement was noticeable within the first week or two. Along 26th Street, Hoftiezer said, the system has also helped get traffic flowing after a train. Even while a train is crossing, the signals keep track of the number of vehicles waiting and how long they've been sitting, then clears traffic in a way that minimizes problems.
©2018 the American News (Aberdeen, S.D.) Distributed by Tribune Content Agency, LLC.
