While Seattleites were busy adjusting their commutes during last week’s Alaskan Way Viaduct closure, SDOT was busy adapting our signal system to changing traffic demands with Traffic Responsive Signal Operations. Traffic responsive signal systems respond to real-time volume and occupancy data to select a predefined timing plan to best serve current traffic demand.
SDOT's Traffic Management Center, aka the TMC
SDOT’s Traffic Management Center (TMC) is the hub where all of the city’s traffic control systems are monitored. Detection technology, including a robust network of cameras, sends up-to-minute data to the TMC where informed decisions can be made to improve traffic flow throughout the city. During last week’s Viaduct closure, SDOT staff relied heavily on this technology to maximize the effectiveness of our roadway network given the circumstances. Staff kept an eye on traffic from the TMC and worked to optimize traffic signal timing wherever and whenever possible.
SDOT has installed traffic responsive signal systems along several key corridors including: Elliott Avenue W/15th Avenue W from W Harrison Street to W Armour Street, First Avenue S from S Royal Brougham Way to S Spokane Street, Fourth Avenue S from S Royal Brougham Way to S Spokane Street, E Marginal Way S from S Idaho Street to the First Avenue S Bridge, 15th Avenue NW from Market Street to Holman Road NW, and Aurora Avenue N from Winona Avenue N to N 145th Street.
Being responsive to actual traffic demand based on real-time data has broad implications for traffic management in Seattle during major road closures and beyond. After all, morning and afternoon commutes are dependent on a number of unpredictable factors like traffic volumes, weather conditions, collisions, emergency operations, etc. Traffic responsive systems handle these unknowns exponentially better than older signal systems that relied on fixed signal phases and internal clocks. Instead of sticking with static signal phasing based on the time of day, these new signals automatically adjust to account for demand!