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Traffic signal considered at Longview bridge

The Lewis and Clark Bridge between Longview, Wash., and Rainier is a main route to Portland and other points for Clatsop County residents. (Washington Department of Transportation)
Friday, June 29, 2018

The Oregon Department of Transportation thinks a traffic signal is warranted on Highway 30 at the Lewis and Clark Bridge near Longview.

Analysts evaluated the congestion causing traffic backups in both directions on Highway 30, including into the city of Rainier.

There is no identified project or a funding source for the work, however.

The Lewis and Clark Bridge has numerous limitations that create bottlenecks. It’s a narrow two-lane structure with steep grades.

There are few options to alleviate the congestion outside of replacing the existing bridge or building another one. A new bridge or major enhancement project likely isn’t feasible due to the tremendous cost and lengthy design and approvals process, ODOT reported.

The bridge is under the jurisdiction of Washington state’s Department of Transportation. Last year, traffic was backing up into Rainier during peak travel times. The backups increased noticeably last year as did back-ups on the Highway 30 approach from Astoria.

ODOT has identified plans to install a dynamic queue warning system for eastbound traffic to address safety concerns of slow/stopped queues alongside high-speed, downhill flows.

Currently, signs on the bridge entrance ramps indicate that eastbound traffic should proceed directly onto the bridge while westbound traffic should yield. It’s necessary to prevent crashes when eastbound traffic is backed up on the downgrade where there are blind curves and high-speed traffic.

In the traffic analysis, ODOT considered different traffic controls, such as switching the yield and stop control of the two approaches to modify where vehicles queue. While this switch would shorten the queue in Rainier, where speeds are slower and there is another traffic control, it would increase serious crashes on the high speed, downhill eastbound section that already has more severe crashes than the approach from the city.

The proposed new signal went through significant review by the state traffic roadway engineer because it would operate in an unconventional manner.

A future signal would be used to manage traffic entering the bridge much like ramp meters used on urban freeways, rather than controlling traffic from multiple directions as do signals at typical intersections.

ODOT will continue to monitor traffic around the bridge and will continue to work in cooperation with Washington officials and the city of Rainier.

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