SR 524 - Locust & Larch Way - Intersection Improvements

Project news

Why did WSDOT build roundabouts at the intersections of SR 524/Locust Way and SR 524/Larch Way?
Prior to the roundabouts being built, these intersections had collision rates higher than the state average when compared to similar highways. 

Collision history
There were 81 collisions at these intersections from 2011 through 2015, approximately 16 each year. There were 36 injuries to drivers and passengers as the result of these collisions.

  • 47 rear-end collisions
  • 16 turning collisions
  • 11 fixed object collisions
  • 6 opposite direction collisions
  • 1 overturned vehicle

Roundabouts have a proven history of reducing collisions.
With approximately 16,000 trips on this stretch of SR 524 each day, improvements were necessary to reduce the number of collisions and keep traffic moving on Filbert Road. 

Intersection options studied
WSDOT considered six options for these intersections, but most required a wider highway to implement them. Widening will cost substantially more money than currently available because widening will need to address two creeks, a wetland, a narrow bridge built in 1935, right of way, and the I-405 bridge columns. Learn more about the options studied by WSDOT.

Congestion relief will require a separately-funded project
The roundabouts are a safety project designed to reduce the risk of collisions through these intersections.

There may be a slight improvement in through-traffic because cars will no longer need to block traffic while stopping to make a left turn.

Widening this section of SR 524 was included on the Regional Transportation Investment District list of projects for funding on the 2007 Proposition 1 ballot measure. Since voters defeated the measure, no funding has been identified to complete the widening of SR 524. A congestion-relief project will require widening the road, which is a more substantial project that we can accommodate with the current funding level. 

The End Result
Two roundabouts designed to operate in tandem to reduce the frequency and severity of collisions.

Project Benefits

  • Two new roundabouts that will reduce collisions on SR 524.
  • Roundabouts encourage traffic to keep moving at lower speeds, reducing the frequency and severity of collisions.
  • Drivers are less likely to be caught in a lengthy backup due to a crash.
  • Roundabouts are less expensive to build and maintain compared to traffic signals.


  • October 18, 2016 - Open house held at Lynnwood High School.
  • January 2018 - Project is scheduled to be advertised for competitive bidding
  • Spring 2018 - Project is awarded to A-1 Landscaping and Construction, Inc. of Snohomish.
  • Summer 2018 - Construction underway.
  • Fall 2018 - Construction is operationally complete.


Financial Data for PIN 152411B
Funding Source Amount ($ in thousands)
2003 Gas Tax (Nickel Funding) $0
2005 Gas Tax (TPA) $0
Pre-Existing Funds (PEF) $5,127
CWA $0
Total $5,127


Frances Fedoriska
WSDOT Communications

A small map showing the location of Locust and Larch Ways on SR 524 near Lynnwood and Bothell, Washington.

Aerial view of the new roundabout at SR 524 and Larch Way

Crews finish new roundabouts on SR 524 at Locust and Larch ways
View larger photos