The intersection of SR 510 and Rockcress Drive Southeast has a history of collisions. 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.
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 can ride up on the curb to complete the turn. Approximately 12,000 vehicles and 500 trucks use this intersection daily.
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.
Engineers consider:
- 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.
Project amount will be available after project is awarded to private contractor.
There are no related maps and drawings.
Learn about modern roundabouts which are built to serve emergency vehicles, buses, and truck and trailer combinations.
If you are new to roundabouts, WSDOT has a video on how to travel roundabouts.
