November 2009
- Check out Smarter Highways and our brand new video on YouTube to learn about the latest active traffic management tools and technology included in this project.
- Drivers may notice vertical poles popping up along northbound I-5. These will be the legs of the sign bridges. Be prepared for nighttime lane closures on northbound I-5 as they do this work.
- Want to know more about making our highways smarter? Check out our folio (1 MB).
Crews will install a series of electronic speed-limit and lane status signs over each northbound lane on I-5 between Boeing Access Road and I-90 in Seattle. The new signs, expected to activate summer 2010, are the latest smarter highway technology aimed at increasing safety and reducing collisions.
This new traffic technology, also known as active traffic management (ATM) is a key element of WSDOT’s congestion relief program, Moving Washington, and will help manage traffic during the Alaskan Way Viaduct replacement. Along with strategically adding new roadway capacity and managing the demand for lane space with more commute choices this statewide solution also uses technology and new techniques to make our highways more efficient and our transportation system better prepared for increasing traffic demands.
An innovative approach
I-5 commuters will experience safer and smoother traffic on a roadway that detects changing traffic flows and automatically adapts to traffic congestion by adjusting the speed limit and providing drivers with useful traffic information.
The signs will display speed limits from 40 to 60 mph, depending on traffic levels. The result will be fewer traffic collisions and less collision-related congestion.
Automatic variable speed-limit technology is the latest innovation under WSDOT's Moving Washington program, which is using new tools to reduce congestion, improve traffic flow and manage congestion.
Safer roads mean less congestion
The project is designed to improve traffic safety and highway efficiency in one of the state's busiest corridors. Fewer collisions mean less congestion, especially on this stretch of highway where collisions account for as much as 70 percent of congestion.
Drivers get better traffic information
The speed-limit signs also will alert drivers with a lighted arrow to warn of an approaching lane closure and a red ‘X’ at the closed lane to better manage blocking incidents.
Drivers will see varying speed limits, alerts or even blank signs, depending on traffic conditions. Electronic signs will display traffic alerts and information, such as backups and incidents ahead and alternate route suggestions.
New highway sign technology
- WSDOT will install 15 new sign bridges, or gantries, between the Boeing Access Road and I-90 on northbound I-5.
- Sign bridges will support electronic lane status and speed-limit signs over each lane and electronic message boards that warn of backups ahead.
- Signs will be linked to traffic sensors that record traffic speed and volume used to determine the speed limit.
- The Washington State Patrol will enforce speed limits as displayed.
Smart highways
WSDOT crews will install other intelligent transportation system (ITS) components to improve conventional signs along the roadway. All of this technology is included in WSDOT's smart-highways approach, widely known as active traffic management (ATM). The tools use information technology to make our roadways, access ramps and bridges operate as efficiently as possible.
Coming to a highway near you
Smart-highway technology is planned for the central Puget Sound region's busiest corridors, including I-90 and SR 520 between I-405 and I-5. Additional smart-highway tools will be installed on I-90, SR 520 and I-405 in the near future.
Already, crews have installed electronic variable speed limit signs on I-90 between Bellevue and Seattle.
Why is WSDOT
using technology to improve I-5?
Active traffic management tools have proven effective at reducing collisions and improving traffic flow in Europe. This technology has resulted in several benefits including a 30 percent reduction in collisions and a 22 percent increase in roadway capacity.
Installing active traffic management signs on I-5 will help keep people and goods moving during initial construction for the Alaskan Way Viaduct and Seawall Replacement Program.
The Alaskan Way Viaduct, part of SR 99, is one of the most heavily traveled north-south routes for freight and commuters through the Seattle area. Construction to replace or repair the viaduct could increase traffic levels on parallel routes, such as I-5.
The End Result
The new signs will post variable speed limits that will warn drivers of backups ahead and smooth out traffic as it approaches a lane block incident. The overhead signs also can quickly close entire lanes and provide warning information to drivers before they reach slower traffic.
This advance notification and variable speed limits will help reduce collisions that cause backups and stop-and-go traffic. The new system will make I-5 safer and help us better manage and clear blocking incidents.
Project Benefits
- Safer driving with fewer collisions
- Less collision-related congestion
- Less congestion caused by traffic increases during replacement of the Alaskan Way Viaduct
- Better information for drivers about traffic problems ahead, travel times and alternate routes
- Less waiting for traffic-blocking incidents to be cleared from highway lanes
- A more efficient I-5 that performs closer to its true potential
What is the project timeline?
Mar. 11, 2009 - We awarded the sign bridge construction contract to C.A. Carey Corp.
May 2009 - We started constructing the sign bridges.
June 2009 - We selected Elcon Corporation to install the ATM signs.
January 2010 - We plan to start installing the new ATM signs on the sign bridges.
July 2010 - We plan to activate the new ATM signs.
Financial Information
The I-5 Variable Speed Safety project is funded as part of WSDOT's Alaskan Way Viaduct and Seawall Replacement project.
- Available funding for preliminary engineering: $2 million.
- Available funding for construction: $21.8 million
Total available funding: $23.8 million
How can I get more information?
Contact:
Jennifer Charlebois, P.E.
WSDOT Project Engineer (electronic signs)
Urban Corridors Office
401 2nd Ave. S.
Seattle, WA 98104
Phone: 206-716-1106
Mark Sawyer, P.E.
WSDOT Project Engineer (sign bridges)
3241 118th Ave. SE
Bellevue, WA 98005
Phone: 425-649-4429
Patricia Michaud
WSDOT Communications
Urban Corridors Office
401 2nd Ave. S.
Seattle, WA 98104
Phone: 206-716-1133
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