I-90 Two-Way Transit and HOV Operations - Variable speed limit and safety signs

As part of WSDOT and Sound Transit’s I-90 Two-Way Transit and HOV Operations project crews installed 14 electronic speed limit signs on westbound Interstate 90 from just west of I-405 in Bellevue to Rainier Avenue in Seattle which will allow varying speed limits to be displayed. We expect these signs will increase safety, decrease collisions and keep traffic moving during construction on westbound I-90 by alerting drivers to reduce their speed when backups or collisions are on the road ahead. 

Tried and true on our mountain passes
WSDOT uses variable speed limit signs on US 2 at Steven Pass and on I-90 at Snoqualmie Pass to alert drivers to slow down during icy, snowy and congested driving conditions. Similar signs installed on European urban roadways incresed safety and decrease congestion-related collisions by 30% or more.

Sign of the times is safety
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 limits signs, similar to those seen on US 2 at Stevens Pass
• 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 tunnel is closed. These energy-efficient signs replace existing

Moving Washington through Smarter Highways
Variable speed signs are the latest traffic technology aimed at increasing safety and reducing collisions. This new traffic technology is a key element of WSDOT’s congestion relief program called Moving Washington. 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.