Well this is a first.

Literally, the first roundabout in the state of Washington to feature a metered traffic signal, the very thing the roundabouts were put in for to replace in the first place, is being turned on Tuesday.

WSDOT

In 2007, WSDOT built a roundabout at the intersection of Steptoe Street and Columbia Park Trail off of State Route 240 to relieve congestion and ensure better traffic flow. However, increased urban growth and traffic volumes over the past 11 years has presented a new challenge. During peak travel hours, traffic is starting to back-up onto the eastbound off-ramp of SR 240, which creates opportunity for high speed, rear-end collisions

The Washington State Department of Transportation will activate the new metered signal which is located about 100 yards from the roundabout entrance going westbound on Columbia Park Trail before entering the roundabout at SR 240 and Steptoe.

This particular roundabout has been modified before. The roundabout was whittled down to one approach lane in two of the four entrances in 2016.

The cost is $100,000 for the traffic meter and associated equipment. The gear is in place and ready to go. An engineering crew will calibrate the system Tuesday and turn it on.

Sensor “loops” embedded in the off-ramp will detect stopped traffic and activate the red-green meter on Columbia Park Trail. You are highly encouraged to not run the red metered light.

When the meter is active, westbound drivers on Columbia Park Trail will have to wait for a “green” to even get to the roundabout entrance.

A green light does NOT mean you are free to enter the roundabout. Drivers must still follow the roundabout rules, which includes yielding to traffic approaching from the left and semi trucks which turn wide and can’t stop quickly.

For now, the plan is only to flip the switch afternoons Monday through Thursday. If it is a success, WSDOT might consider another meter at another entrance to ease the morning commute hassles at the roundabout. Officials hope the metered gap loops will ease congestion on all sides of the roundabout.

More here.