US 12 and SR 7 - Intersection Improvements

This intersection was identified as a location for a roundabout  that would increase safety under the I-2 Collision Prevention program due to the number and severity of collisions observed during a five-year period between   2015 and 2019.   

All collisions involved vehicles driving south on SR 7, with many collisions occurring when drivers were turning left onto US 12.  Between 2015 and 2019, there were ten collisions at this intersection, some causing serious injuries. All involved cars going south on SR 7, and most happened when drivers were turning left. Similar patterns of collisions are continuing and show there is a need to make safety improvements. Studies show that roundabouts are safer than traditional stop sign or traffic signal-controlled intersections.  They also allow for truck and large vehicle movement through the intersection. 

Roundabouts reduced injury crashes by 75 percent at intersections where stop signs or traffic signals were previously used for traffic control, according to a study by the Insurance Institute for Highway Safety (IIHS). Studies by the IIHS and Federal Highway Administration (FHWA) have shown that roundabouts on average: 

Community Feedback: 

Community members who live or work in the area, as well as the travelling public were invited to complete a survey from August to September 2024.  We received over 90 responses and will use the feedback to help us design for: 

Q&A  

Why a roundabout?  
 Modern roundabouts are a safe option for managing speed so vehicles can enter the intersection from SR 7 and join more easily into US 12 traffic.   

Roundabouts improve overall traffic flow and safety when compared to other types of intersections. By traffic flowing in one direction, potential collisions are reduced. As a result, there are fewer number of turning movements in the intersection when crashes happen, and collisions that occur are less severe.   

Roundabouts ease congestion by moving traffic more efficiently, reduce fuel use and air pollution, and require less maintenance than traffic lights. Roundabouts help slow down traffic naturally by using their shape and design instead of relying only on signs or traffic lights. 

Learn more about the types of roundabout WSDOT considers (PDF 1.8KB)  

I didn’t personally witness any crashes. What crash data did you collect?   
 WSDOT collects crash data from law enforcement following a crash the same way as other states. Crashes are categorized using the KABCO scale (PDF 335KB) based on guidelines established by the Model Minimum Uniform Crash Criteria.  

The data analyzed for this project spans five years, from Jan. 1, 2015, to Dec. 31, 2019, with ten reported crashes.  During this period, two types of crashes occurred at this intersection:   

Data collected between 2020 and 2024 see similar patterns at this location. 

Why did you not consider a signal at this location?  
 The history of collisions at this location were at-angle, also called T-bone, crashes. A signal at this location would not lessen the potential for T-bone crashes as well as a roundabout and could also result in more rear end crashes.   

  Isn’t a roundabout a bad idea for a high-speed corridor like US 12?  
  WSDOT has successfully used roundabouts on high-speed roads across the state. For decades, roundabouts have been a proven way to improve safety and reduce crashes nationally and statewide.  

Here are just a few examples of roundabouts on high-speed corridors in Washington:  

  Will freight trucks be able to use a roundabout?  
 Yes! WSDOT will work with the freight community and other agencies to adjust the roundabout design and accommodate user needs. Typically, roundabout designs include truck-friendly elements like:  

 This roundabout will include a “truck apron.” What is that?   
 A truck apron is a special feature built into a roundabout to help large vehicles make turns. It is a raised section of concrete around the center island that acts as an extra lane for trucks. The back wheels of a large truck can roll over the apron, making it easier to turn. The truck apron is slightly raised and often a different color or material than the road to keep smaller vehicles from using it since it is not meant to be a regular driving lane. 

But there is so much truck traffic!  
 A good example of a successful roundabout on a high-speed road with heavy freight traffic is the SR 500/NE 182nd Intersection Improvement project. In 2022, a compact roundabout was built at this location. On average, about 5,000 vehicles pass through this intersection each day, and 26% of that traffic is freight vehicles. 

Why was this intersection chosen over other nearby areas?  
 While crashes occurred at other intersections, the severity of crashes was significantly higher at the intersection of US 12 and SR 7. This intersection was found through a data-driven review of the state's roads, focusing on accidents that caused serious injuries or deaths. Intersections were chosen based on the number of crashes that happened each year, with the goal of finding places where improvements would make the biggest difference.   

Don’t roundabouts create more traffic and backups?  
 Many people believe roundabouts slow down traffic, but they help vehicles move through intersections more quickly and with less traffic. Roundabouts promote a continuous flow of traffic. Unlike intersections with traffic signals, drivers don’t have to wait for a green light at a roundabout to get through the intersection. Traffic is not required to stop – only yield – so the intersection can handle more traffic in the same amount of time.   

Studies by Kansas State University measured traffic flow at intersections before and after roundabouts. In each case, building a roundabout led to a 20 percent reduction in delays. Studies by the Insurance Institute for Highway Safety (IIHS) of intersections in three states, including Washington, found that roundabouts contributed to an 89 percent reduction in delays and 56 percent reduction in vehicle stops. Studies by the Federal Highway Administration (FHWA) show roundabouts can increase traffic capacity by 30 to 50 percent compared to traditional intersections.  

Roundabouts are confusing and will cause more crashes!  
 WSDOT understands that learning how to move in new traffic patterns can be an adjustment.  However, we have seen time and time again that after a roundabout is constructed, the community quickly learns and becomes more comfortable using the roundabout. If you are new to driving through roundabouts, learn how to navigate a roundabout here.  

Did WSDOT do public engagement on this project? 
 A survey was taken during the planning stages of this project in 2024.  As the design moves forward, the WSDOT project team will create more opportunities to hear from the community and work with nearby groups, including freight companies, fire departments, property owners, county emergency managers, and first responders. By working closely with these road users, we can make sure the roundabout is designed to fit the needs of all types of vehicles that use the intersection. 

 How are you funding this project?  
 This roundabout installation project is funded through a portion of the WSDOT Safety Improvement (I2) Program. The goal of this program is to make roads safer by reducing and preventing crashes. It focuses on high-risk areas where safety improvements are most needed. After reviewing and scoring several locations, this intersection was chosen as top location to improve safety with construction of a roundabout.  

Are more roundabouts going to be installed in Southwest Washington? 
 It’s true! Roundabouts are here to stay as a tool in the toolbox to address safety and efficiency, but they may not be the solution for every intersection. Several factors are evaluated when deciding to build a roundabout at a specific intersection: