March 13, 2015

Reduced vehicle weight and speed limits are coming for traffic on the Morrison Bridge, as Multnomah County takes steps to keep the bridge in service until the deteriorating lift span deck is replaced.

The gross vehicle weight limit on the bridge will be reduced from the current 40 tons (80,000 pounds) to 10 tons (20,000 pounds). The goal is for the new weight limits to go into effect on Monday, April 13. Bridge speed limits will be reduced from 35 to 25 miles per hour. New speed limit signs will be installed the week of March 16.

In a notice sent to local freight industry groups, the county announced that “the deterioration of the fiber reinforced polymer deck on the Morrison Bridge lift span has reached the point where the County needs to reduce the vehicle weight and speed limits on the bridge in order to keep the bridge open. Our analysis has led the County Engineering staff to conclude that keeping heavy vehicles off the bridge and reducing the impact from high speed vehicles is the best and least costly method to extend the life of the deck until it can be replaced. Multnomah County’s goal is to have as many traffic lanes open as possible to cars and small trucks until the new deck is installed.”

A traffic plan for overweight vehicles is being developed in consultation with other agencies and freight interest groups. Signage will be installed prior to the weight limits taking effect. The weight limits will require one TriMet bus route (Line 15-Belmont/NW 23) and several C-TRAN morning routes to use alternate routes. Transit agency staff are working on new bus routes that will delay riders as little as possible.

County staff are working to complete deck repairs that have closed two traffic lanes on the bridge. The county plans to reopen the closed lanes after the weight limits go into effect. Cars and small trucks represent the vast majority of the estimated 50,000 vehicles that cross the bridge each day. County engineers are working with an engineering consultant to select a design option for the new deck so that design work can begin this year. The existing deck was installed in 2011-12 and has been the subject of recent litigation.

Multnomah County maintains six Willamette River bridges and 300 miles of roads. For more information, visit www.multco.us/bridges.