From 7 p.m. to 5 a.m. Monday, May 18 and Tuesday, May 19, travelers should expect lane reductions and single-lane alternating traffic on SR 510 at McAllister Court Southeast/Rockcress Drive Southeast near Lacey. More information below.
Project overview
Crews will build a single-lane roundabout on State Route 510 at the intersection of McAllister Court SE/Rockcress Drive SE in Lacey. The improvement will reduce the potential for collisions.
What to expect
Beginning Monday night, May 18, contractor crews working for WSDOT will begin mobilizing for roundabout construction.
From 7 p.m. to 5 a.m. Monday, May 18 and Tuesday, May 19, travelers should expect lane reductions and single-lane alternating traffic on SR 510 at McAllister Court Southeast/Rockcress Drive Southeast near Lacey.
Construction in stages
Crews will work in stages to build the roundabout, primarily during daytime hours. Some intermittent weeknight work may occur as needed between 7 p.m. and 5 a.m.
Major construction during daytime hours is scheduled to begin later this spring.
Travelers can expect shifted lanes and temporary speed limit reductions of 25 mph through the work zone. Temporary traffic signals will direct one-lane alternating traffic around the clock for up to 60 days during construction.
Crews will not work during Memorial Day weekend.
More detailed information regarding closures and traffic changes will be made available as construction schedules are confirmed.
Construction projects in the area
Several roundabout projects near the Thurston/Pierce County line are expected to start this year:
- Yelm - SR 510 between Cullens Road and 170th Street SE
- Yelm - SR 507 at Bald Hill
- McKenna - SR 702 at Harts Lake Road South
- Spanaway - SR 507 at 208th Street East
A roundabout is planned for the intersection of SR 510 and McAllister Court Southeast/Rockcress Drive.
The intersection of SR 510 and Rockcress Drive Southeast has a history of collisions. As a result, WSDOT conducted a pre-design study of this intersection. Following the study, crews will build a roundabout at this intersection.
Roundabouts help reduce the potential for collisions while keeping traffic moving.
Roundabouts reduce the number of conflict points. A conflict point is an area on a road where paths cross, merge, or diverge.
During 2024, approximately 14,000 vehicles used this intersection daily.
Other benefits:
Low travel speeds – Drivers slow down and yield to traffic. Speeds in the roundabout are between 15 and 20 miles per hour. The few collisions that occur in roundabouts are minor. Roundabouts also reduce the severity of injuries since they occur at low speeds.
No light to beat – Roundabouts promote continuous flow of traffic. Drivers yield to traffic before entering a roundabout. If there is no traffic in the roundabout, drivers are not required to stop. Drivers don't have the incentive to speed up to try and "beat the light".
One-way travel – Curved roads and one-way travel eliminate the possibility for T-bone and head-on collisions.
Roundabouts instead of traffic lights
The history of collisions at this location are typically T-bone crashes. A traffic signal doesn't eliminate the possibility of those types of collisions. A traffic signal may also increase the number of rear end crashes. Roundabouts also help promote traffic flow.
Semi-trucks and roundabouts
Roundabouts on state highways accommodate semi-trucks. This roundabout will have a mountable curb. The curb acts as an extra lane for semi-trucks hauling trailers. The back wheels of the semi can ride up on the curb to complete the turn.
Latest roundabout on SR 510 between Lacey and Yelm
This roundabout is the latest in a series of roundabouts built on SR 510. This will be the sixth roundabout built on the highway. The latest were opened on Yelm Highway and nearby Reservation Road.
Roundabouts help address safety and efficiency. They may not be the ideal solution for every intersection. Several factors are evaluated.
Key engineering considerations
- Collision history - The number of collisions, types of collision, speeds, and other contributing factors.
- Intersection operation - Current and projected travel delay and backups when comparing a traffic light, stop sign or a roundabout.
- Cost - This goes beyond construction costs. The considerations include requirements to buy land and long-term maintenance expenses.