New electronic speed signs on I-90

The latest traffic technology aimed at increasing safety and reducing collisions is coming soon to I-90. Beginning this past Monday, drivers will see activity on new electronic speed signs installed last fall on the westbound shoulders of I-90 between I-405 and I-5.

Drivers can expect to see a series of test sequences — symbols or letters — on the new electronic signs during testing. Traffic engineers need to test the new signs to make sure that they are ready for around-the-clock operations. The testing, which takes several months, is a visible heads-up to drivers that the signs should be activated and enforceable by late April.

“We are committed to continue to use our highways more efficiently,” said Paula Hammond, Secretary of Transportation. “I-90 is the east-west backbone of our highway system, and these new signs will help to keep people and goods moving while making roads safer.”

This new traffic technology is a key element of WSDOT’s congestion relief program called Moving Washington. Along with adding new roadway capacity and managing the demand for lane space with more commute choices, the undertaking also uses technology to make highways more efficient and the transportation system better prepared for increasing traffic demands, according to WSDOT officials.

This latest addition of smart highway technology is part of the I-90 Two-Way Transit & HOV Operations Project, providing a new HOV lane across Lake Washington in each direction and new HOV connections with Mercer Island and Bellevue.

To improve safety on westbound I-90, crews installed the variable speed limit signs to alert drivers to slow their speeds before nearing collisions or backups on the road ahead. WSDOT uses similar signs on U.S. Highway 2 at Stevens Pass and on I-90 on Snoqualmie pass to alert drivers to slow down during icy, snowy and congested driving conditions. Similar signs installed on busy, urban roadways in Europe have reduced congestion-related collisions by 30 percent.

Drivers may have already noticed these variable speed signs and a number of other new signs along westbound I-90 between I-405 in Bellevue and I-5 in Seattle. Crews working on the project for WSDOT and Sound Transit installed four different types of signs:

• Overhead electronic message signs will display a variety of driver information including trip times and incident information

• Variable speed/tunnel signs, which will display the current speed limit, but will also change to display a warning message when the tunnel is closed.

• Tunnel information signs, which are normally blank, but display messages when the Mount Baker Tunnel or First Hill Lid are closed. These signs will replace the existing neon signs.

In last week’s story on I-90 bridge closures this May and July, information regarding the July closures was incomplete. All normal westbound 1-90 lanes will be closed July 5-28; however, the center express lanes will be open for traffic.

For more information on new signs and other information go to

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