Adaptive Signal

Adaptive Signal Control Technology

 

Puyallup has implemented adaptive signal control technology on four arterials:
  • The "bypass" corridor (3rd Street SE/2nd Street NE) from Meridian to River Road
  • Meridian (SR 161) from River Road to 23rd Avenue SE
  • River Road from Meridian to 11th St. NW
  • 9th Street SW between 31st and 39th Avenue

In 2015, the signal lights along Meridian and 3rd and 2nd Streets NE (aka “the bypass”) in Puyallup’s downtown were outfitted with a system designed to improve traffic flow by adjusting signal timings based on demand. The system was then expanded to River Road and has most recently been installed along part of the 9th Street corridor.

The adaptive traffic system monitors roadway volume and uses real-time data to manage current traffic conditions. The system evaluates the data and adjusts the signals based on the most efficient way of allowing traffic to proceed.

In this way, the system is able to keep vehicles in motion with as few stops as possible. Here’s proof, via impressive increases in the number of vehicles served at certain intersections on 9th Street SW (these numbers are preliminary pending a fuller study):

ATS 9th prelim results charts

The 9th Street SW corridor sees about 31,000 vehicle trips each weekday. By prioritizing where and when travel is heaviest, the adaptive system optimizes northbound movement during the morning peak travel period and southbound movement in the late afternoon/early evening. In addition to better managing traffic flow at each individual intersection, the system also coordinates movements between intersections which are in close proximity.

The system maximizes traffic flows in three different ways:

  • It automatically chooses between different cycle lengths depending on current traffic demands (i.e. no more immutable pre-set cycles, which means no more waiting at a red light for a pre-determined cycle to finish, despite a lack of oncoming traffic);
  • It modifies the phasing of left-turn arrows and other movements according to actual demand; and
  • It looks at how many vehicles are in a queue and adjusts green times accordingly.

Well-coordinated traffic signals increase safety, cut down on emissions, and save time and fuel. In short, more green lights make each day better!

Project Documents