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Redmond Ridge Drive NE and NE Alder Crest Drive Roundabout Project

Project completed in winter 2024

Crews completed paving, lane striping, and installed native plants in March 2024 to finalize the new roundabout near Redmond, WA. 

Project overview

King County built a single-lane roundabout at the intersection of Redmond Ridge Drive NE and NE Alder Crest Drive. The new roundabout makes it easier for pedestrians, wheelchair users, bicycles, and people with strollers to use the intersection.

Construction work started in September 2023 and lasted until winter 2024.

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Planning ahead to keep traffic moving in the future

Continued growth of the Redmond Ridge community and nearby business park will bring a lot more vehicle traffic to this intersection in the coming years. Building a roundabout now helps to manage projected traffic increase, prevent speeding, and make the intersection safer for middle school students and people walking or rolling to and from the local park and athletic fields. This project provided the county with a rare opportunity to plan now for what the future will bring. Most of the design and construction costs were paid for with state traffic and pedestrian improvement grant money.

Project location map

King County built a new roundabout at the intersection of Redmond Ridge Drive NE and NE Alder Crest Drive. Larger version  PDF 117KB

How to use the roundabout

All vehicles may enter the intersection from all four entry and exit points of the roundabout. Drivers enter the roundabout by yielding to traffic that is already in the circle and drive in a counterclockwise direction until they reach their desired exit point.

Extra room for large trucks

The central island includes a truck apron, a raised section of red concrete that acts as an extra lane for large vehicles. The back wheels of the oversize vehicle can ride up on the truck apron so the truck can easily complete the turn.

Pedestrians and non-motorized vehicles

Signed crosswalks and separated sidewalks allow people to safely walk across all lanes. Accessible curb ramps will make it easier for bikes, strollers, and wheelchairs to use the crosswalks.

Project timeline

  • September 2023 – Construction began
  • October 23, 2023 – November 13, 2023  – 21-day full closure  
  • March 2024 – Construction complete

Project budget

The total cost of this project was $1.54 million. It was mostly funded through state traffic and pedestrian improvement grants. A small amount of county resources was also allocated to this project.

Frequently asked questions

This project provides the county with a rare opportunity to plan now for what the future will bring. The roundabout will help manage projected traffic increase, prevent speeding, and make the intersection safer for middle school students and people walking or rolling to and from the local park and athletic fields.

County traffic engineers looked at several alternative traffic-calming options. Both a traffic light and four-way-stop would require drivers to come to a complete stop at the intersection. A full stop could increase high-speed rear-end collisions on NE Redmond Ridge Drive. A roundabout that slows but does not stop traffic is the safest and most cost-effective choice for this growing region of King County.

Most buses and trucks can get through a single lane roundabout. The central island includes a truck apron, a raised section of red concrete that acts as an extra lane for large vehicles. The back wheels of the oversize vehicle can ride up on the truck apron so the truck can easily complete the turn.

The center island was designed for low maintenance and drought tolerance plants. The county planted four trees and nearly 600 groundcover and shrubs in the center island including lavender, kinnikinnick, and rose glow barberry. 

Photos

The new roundabout at Redmond Ridge Drive NE and NE Alder Crest Drive opened to traffic on Monday, November 13, 2023.

 

 

November 9, 2023: crews prepare the first layer of asphalt for paving the new roundabout at the intersection of Redmond Ridge Drive NE and NE Alder Crest Drive.  

 

Crews plan the next steps of the Redmond Ridge roundabout at NE Alder Crest Dr.

Oct. 31, 2023 – Crews plan the next steps of the Redmond Ridge roundabout at NE Alder Crest Dr. 

 

New roundabout under construction.

Oct. 31, 2023 –Vehicles will be able to enter the intersection when it’s complete from all four entry and exit points of the roundabout. Drivers enter the roundabout by yielding to traffic that is already in the circle and drive in a counterclockwise direction until they reach their desired exit point.

 

A crew member takes more measurements to ensure that after the grinding, the remaining hot mix asphalt (HMA) thickness is the King County standard.

Oct. 31, 2023 – A crew member takes more measurements to ensure that after the grinding, the remaining hot mix asphalt (HMA) thickness is the King County standard. 

 

October 5, 2023: Crews scrape away the road to make space for the new roundabout at the intersection of Redmond Ridge Drive NE and NE Alder Crest Drive 

 

West on NE Alder Crest Drive approaching NE Redmond Ridge Drive

A view of the intersection before the start of construction. The photo above faces west on NE Alder Crest Drive approaching NE Redmond Ridge Drive. The Redmond Fire Station is across the street on the right-hand side.

 

Redmond Ridge Drive facing north.

Redmond Ridge Drive facing north. Photo taken before the start of construction.

 

Aerial view of the new roundabout location.

King County will build a roundabout at this intersection to manage the increase in traffic near the City of Redmond.

 

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