Active Traffic and Demand Management - Choosing locations for ATDM signs

Congestion and safety needs, as well as coordination with other high-impact projects helped identify I-5, I-90 and SR 520 as the ideal locations for Active Traffic and Demand Management.The project to use ATDM on I-5, I-90 and SR 520 cost a total of $65 million.

Northbound I-5: Boeing Access Road to I-90

Northbound I-5 - Boeing Access Road to I-90

This seven-mile corridor was selected because it experienced a significant number of collisions that resulted in or contributed to congestion. This section of I-5 also contains several areas where lanes are reduced there are on- and off-ramps that cause significant lane changes and speed variations. The Alaskan Way Viaduct Replacement project is expected to cause additional congestion on I-5 in this area. Active Traffic and Demand Management on I-5 was funded by the viaduct replacement project to help ease traffic impacts. The cost for this work was approximately $23 million. This system was activated on Aug. 10, 2010.

SR 520 and I-90: Cross-lake corridors between Seattle and Bellevue

SR 520 and I-90 Cross-lake corridors between Seattle and Bellevue

Collision history identified these routes as potential Active Traffic Management corridors. About 60% of the collisions on these routes are congestion-related. Reducing the effects of SR 520 bridge replacement construction and the Sound Transit light rail expansion on I-90 also helped drive the selection of these corridors for active traffic management.

The $42 million improvements on SR 520 and I-90 were funded as part of a Federal Highway Administration Urban Partnership Agreement grant. The grant funds active traffic management, tolling, transit and telecommuting projects. 

WSDOT traffic engineers are also looking at other locations where Active Traffic Management strategies can be used. In addition to electronic signs, WSDOT is considering the use of more "hard shoulder running" lanes. This allows traffic to drive on the shoulder when there is congestion. Opening the shoulder and using active traffic management methods can increase highway capacity and provide temporary relief from congestion. A potential hard shoulder running location has been identified for I-5 from Everett to Marysville. Sections of I-5 through Pierce County area also candidates.