The state’s first diverging diamond interchange is set to open in Lacey following an upcoming weekend closure of State Route 510/Marvin Road overpass above Interstate 5 next month.

The development is a major milestone for the Washington State Department of Transportation’s project that is intended to improve travel and safety in the fast-growing South Sound community.

Locational map of the I-5 - SR 510 Interchange.

Diverging diamond guides travelers through
Clearly marked signs, pavement markings and traffic signals intuitively guide people traveling through the upgraded interchange. Vehicles are briefly directed to the other side of the roadway where they cross back over or merge onto I-5.

A diverging diamond interchange, already in use in many other states, moves vehicles more efficiently than a traditional interchange. They also reduce the potential for collisions as the innovative design removes areas where vehicles merge, diverge or cross.

In order to transform the interchange, WSDOT’s contractor will close the Marvin Road overpass along with the adjacent I-5 off- and on-ramps during the last weekend of the month.

See more virtual drive through videos at https://www.wsdot.wa.gov/projects/i5/sr510interchange/videos

Closures details
9 p.m. Friday, July 31 – 5 a.m. Monday, August 3

  • Marvin Road overpass between Quinault Drive Northeast and Main Street Northeast.
  • Both Marvin Road on-ramps to southbound I-5 and northbound I-5.
  • Northbound and southbound I-5 exits to Marvin Road.

Weekend travelers through the area should plan ahead to reach their destinations in time.

The work is weather-dependent and could be rescheduled due to rain.

Once open in the new configuration, additional work will continue on the project, which include new concrete islands and other associated work.