The Washington State Department of Transportation is upgrading all of its remaining three-rope median cable barriers in the region to four ropes.
“This gives the new barriers a lower bottom cable and a higher top cable, decreasing the potential of a vehicle going under or over the barrier,” WSDOT spokeswoman Andrea Petrich wrote in a blog post about the project.
Snohomish County spots that still have three-rope barriers, which will be replaced:
– I-5 from 300th Street NW in Stanwood to near Anderson Road in Mount Vernon
– Highway 522 just west of I-405 in Bothell to near NE 195th Street in Woodinville
The $6 million project will upgrade barriers at 12 spots along six different highways in King, Snohomish, Skagit and Whatcom counties, improving nearly 40 miles of roadway. The project also will add new posts, fittings and hardware and remove worn-out pieces.
Cable barriers are a cost-effective way to help prevent cross-over crashes in certain locations. The ropes are designed to absorb the blow of an oncoming vehicle.
WSDOT first installed cable barriers in 1995, in Marysville. In the years following, there were problems with designs and installation, and Marysville became a tragic example.
A 2005 investigation by The Herald that analyzed crash data showed that the barriers failed to stop cars in the median at a disproportionate rate along a three-mile stretch of I-5 in Marysville. A subsequent state study found the barriers were improperly placed and allowed vehicles to duck under the cables.
A second set of cable barrier was installed, but the move didn’t prevent larger vehicles from blasting through.
Following another fiery fatal crash and an outside expert’s recommendation, Gov. Chris Gregoire in 2007 ordered state transportation officials to make plans for a concrete barrier in a 10-mile stretch of I-5. The concrete barriers were installed in 2010.
Meanwhile, designs for cable barriers have been greatly improved.
As of 2011, four-rope systems had experienced far fewer instances of vehicles breaking through the barrier, and of all crashes into those barriers, none resulted in serious injuries or fatalities, according to a 2013 WSDOT report, the latest available.
Have a question or topic for Street Smarts? Contact email@example.com or 425-339-3432.