Speed Limit Assessment Projects

Want to request a speed limit or speed zone change?

Call the 24/7 Road Helpline at 206-477-8100 or email maint.roads@kingcounty.gov. 

Program overview

Between 2014-2023, 33% of traffic fatalities in King County were due to a speeding driver.

Reducing speed limits can make roads safer for everyone. When vehicles go slower, drivers have more time to react to sudden changes. Slower speeds also reduce the force of crashes, which means fewer serious injuries. It helps pedestrians and cyclists feel safer too, encouraging more people to walk or bike. By lowering the speed limit, we create safer and more pleasant communities for everyone.

This work supports the King County Target Zero Traffic Safety Strategic Plan for 2024-2027, which includes a goal of zero traffic deaths and serious injuries on roads in unincorporated King County. Using the Safe System Approach, we aim to reduce the likelihood and severity of crashes by lowering speed limits in locations where current speeds create higher safety risks.

Community involvement

For each speed limit reduction proposal, Road Services opens a 14-day public comment period. We use the comments provided to help our decision making and better understand how a reduction may impact the community and the people who use the road. This is not a simple yes or no vote. Sometimes community members offer alternative suggestions that are incredibly valuable and can be incorporated into road improvements.

Safety benefits of speed limit reduction 

Reducing the posted speed limit has many safety benefits. Here are some key advantages: 

• Reduced traffic collisions and severity: Slower speeds give drivers more time to react to unexpected situations, which lowers the chance of collisions and reduces the severity of crashes.
• Improved pedestrian safety: Gives drivers more time to notice and react to pedestrians at crosswalks or along the road. Reduced speeds can also decrease the severity of injuries in case of collisions involving pedestrians. 
• Shorter stopping distances: Slower speeds mean shorter stopping distances. This can be critical in situations where a driver needs to stop suddenly, such as when a vehicle ahead brakes unexpectedly or when approaching an intersection.
• Encourages walking, biking (active transportation): Lower speed limits can make roads more comfortable for pedestrians and cyclists. This can have positive effects on public health and reduce traffic congestion. 

What is the process for getting a speed limit reduced in my community?

The process to consider a speed limit reduction on a road in unincorporated King County has several steps:

1. Concern is identified: A concern about the speed limit on a road can be brought by a community member or a Road Services team member.
2. Data collection and review: The Road Services staff visit the area and use tools to count vehicles and measure speeds. We also look at the road itself to better understand how it is used and if the speed limit is appropriate for the real-world conditions. This part of the process often takes six to eight weeks. Next, the county reviews the data and determines if a speed reduction proposal is warranted. 
3. Outreach period: If the speed limit outreach period is approved, then we share the proposal with the community and open a 14-day public comment period. Community members can share their comments through an online form or by sending a letter. The comments are tabulated and summarized.  It is important to note that comments received do help us better understand the community’s perspective, however comments are not counted as votes.
4. Review comments: Road Services staff meet and discuss the results and review comments.
5. Decision on speed limit proposal is made: Once a decision is made, we will post it on this website and send an email to those who shared their email address on the feedback form. 
6. If approved, new speed limit signs are installed: Once the change is approved, we submit a work order for the new signs. Installing the signs usually takes about 8 to 10 weeks after the order is placed.

What is King County’s procedure for evaluating speed limits?

King County follows Washington State law, King County Code and national guidelines to determine appropriate posted speed limits.

In 2018, a new rule allowed the Director of Local Services to change speed limits by up to 10 mph based on certain factors including:

• Road conditions and visibility
• How fast most people drive
• Nearby activity centers and destinations
• Safe speeds for curves and tricky spots
• Parking and pedestrian activity
• Recent collision history

If a short piece of road (less than 1 mile) has a different speed limit than the roads around it, the County can change the speed limit by up to 5 mph without a detailed review. This often happens when a city takes over part of a road and changes the speed limit, leaving a small part with a different limit.

For other changes, the County first looks at the road and then asks for public comments for two weeks. These comments are reviewed by the County Traffic Engineer and County Road Engineer. If approved, they make a recommendation to the Director of Local Services, who sends it to the King County Council to make it official. 

2026 Speed Assessment Projects

View a map of active 2026 locations: 

Vashon Locations

• SW Gorsuch Road between Vashon Highway SW and 91st Ave SW
  Overview: A new 41-unit housing development has been constructed at 95th Place SW, with tenants expected to move in as early as September 2026. This .5-mile area is windy and contains hills, and the new development is expected to increase the number of pedestrians along SW Gorsuch Road.
  • Proposed: Reduce the existing speed limit from 35 mph to 25 mph and add additional speed limit signage for drivers traveling east.
• Vashon Highway SW between SW 171st Street and 300 feet north of SW Cove Road
  Overview: Road Services recently conducted a review of the existing speed limit on Vashon Highway SW, north of the Vashon Town Center. The review included the intersections of SW Cove Road and SW Gorsuch Road.
  
  Based on the findings of the review, we recommend extending the existing 25 mph speed limit on Vashon Highway SW north of the town center to include both the SW Cove Road and SW Gorsuch Road intersections.
  • Proposed: Reduce the existing speed limit from 40 mph to 25 mph for a length of about 875 feet.

2025 Speed Assessment Projects

Public comment for the locations listed below took place in December 2025. All 10 locations have been approved and are either completed or scheduled for implementation.

White Center locations

• SW 106th Street and SW 107th Street from Seolia Beach Drive SW (city of Seattle limit) to 12th Avenue SW (plus three short sections of connecting roadway to the east)
  • Proposed: Reduce posted speed limit from 30 mph to 25 mph.
  • Result and action: Implementation planned for Fall 2026.
• 4th Ave SW from SW Roxbury Street to SW 116th Street
  • Proposed: Reduce posted speed limit from 35 mph to 25 mph.
  • Result and action: Following public comment, the speed limit was reduced to 25 mph in March 2026.
• Des Moines Memorial Drive S from 200’ south of S Director Street to S 108th Street
  • Proposed: Reduce posted speed limit from 35 mph to 30 mph.
  • Result and action: Implementation planned for Fall 2026.
• SW 102nd Street from 16th Avenue SW to 4th Avenue SW.
  • Proposed: Reduce posted speed limit from 30 mph to 25 mph.
  • Result and action: Following public comment, the speed limit was reduced to 25 mph in July 2026

Union Hill/Novelty Hill area

• NE Novelty Hill Road from Eastridge Drive NE to Redmond Ridge Drive NE

  • Proposed: Reduce posted speed limit from 45 mph to 35 mph.

  • Result and action: Following public comment, the speed limit was reduced to 35 mph in March 2026.

Lake Youngs area

• SE 240th Street from 196th Avenue SE (city of Covington limit) and 800’ west of 215th Avenue SE (city of Maple Valley limit)

  • Proposed: Reduce posted speed limit from 40 mph to 35 mph.

  • Result and action: Following public comment, the speed limit was reduced to 35 mph in April 2026.

Black Diamond area

• SE Auburn-Black Diamond Rd, 192nd Ave SE and Kent-Black Diamond Rd SE from 168th Avenue SE and 250’ east of 227th Avenue SE (city of Black Diamond limit)
  • Proposed: Reduce posted speed limit from 45 mph to 40 mph.
  • Result and action: Implementation planned for Winter 2026/2027.

Skyway locations

• Renton Avenue S from S 112th Street (city of Seattle limit) and S 130th Street (city of Renton limit)
  • Proposed: Reduce posted speed limit from 30 and 35 mph to 25 mph.
  • Result and action: Implementation planned for Fall 2026.

• Rainier Avenue S from 700’ west of S 106th Street (city of Seattle limit) and 500’ south of S 116th Street (city of Renton limit)
  • Proposed: Reduce posted speed limit from 35 mph to 30 mph.
  • Result and action: Following public comment, the speed limit was reduced to 30 mph in June 2026.

Fall City area

• Preston-Fall City Road SE from SR 202 and SE David Powell Road
  • Proposed: Reduce posted speed limit from 30 mph to 25 mph.
  • Result and action: Implementation planned for Winter 2026/2027.

2024 Speed Assessment Projects

East of Maple Valley

• 276th Avenue SE between the 22800 block of 276th Avenue SE and SE 247th Street
  • Proposed: Reduce the speed limit from 50 mph to 40 mph. There were 13 collisions in this area between 2019 and 2024. There is a school bus stop on this stretch of road and drivers have limited sight distance to the other side of the hill and they can’t see lights on the stopped bus. Our engineers believe that reducing the speed limit would reduce crashes. The original study area was a 0.4-mile section of 276th Avenue SE from Levdansky Park (22800 block) to SE 236th Street. Based on multiple comments from area residents during the comment period, the study area was extended to SE 247th Street. The extension lengthens the study distance to approximately 1.35 miles. The extension provides a consistent 40 MPH speed limit throughout the corridor.
  • Result and action: Following public comment, the speed limit was reduced to 40 mph. The new speed limit signs were installed in September 2025.

Fairwood

• 140th Avenue SE between Renton city limits and SE 192nd Street
  • Proposed: Reduce speed limit from 40 mph to 35 mph
  • Result and action: Following public comment, the speed limit was reduced to 35 mph. The new speed limit signs were installed in January 2025. In addition to lowering the speed limit, the county made additional traffic calming improvements. A full list of these improvements can be found on the Traffic Safety in Fairwood website. Highlights include installing pylons in the center turn lane along 140th Ave SE to prevent drivers from using the center lane to pass slower traffic in the main travel lanes, adding additional speed radar, and new speed limit signs.

Near Black Diamond

• SE Lake Holm Road between SE Lake Moneysmith Road and SE Black Diamond Road
  • Proposed: Reduce speed limit from 40 mph to 35 mph
  • Result and action: Implementation planned for Fall 2026.

Vashon Island

• Vashon Highway SW between SW 182nd St and SW Cemetery Road
  • Proposed: Reduce speed limit from 40 mph to 35 mph
  • Result and action: Following public comment, the speed limit was reduced to 35 mph. The new speed limit signs were installed in August 2024.

• Vashon Highway SW between SW 127th St and SW 153rd St
  • Proposed: Reduce speed limit from 50 mph to 45 mph
  • Result and action: Following public comment, the speed limit was reduced to 45 mph. The new speed limit signs were installed in August 2024.