- 1995 –We installed two miles of low-tension cable barrier along northbound I-5 near 116th St.
- 2000 – We installed seven more miles of low-tension cable barrier along northbound I-5 (from SR 528 to the Stillaguamish River).
- June 2005 - We lowered the speed limit from 70 mph to 60 mph on I-5 through Marysville. The Washington State Patrol emphasized law enforcement in the area.
- January 2006 – We first studied the Marysville area after three fatal collisions between October 2003 and May 2005. We found that the cable barrier was catching 92.4 percent of vehicles that hit the barrier. The majority of Marysville crossover collisions involved southbound sedans that ran into the median, bottomed out in the ditch and nudged beneath the cable barrier.
- August 2006 – As a result of our findings, we installed a second run of high-tension cable barrier near the southbound lanes to reduce the risk of vehicles bottoming out and lifting the cable barrier. Work was completed in January 2007.
- July 2007 – In cooperation with the Washington State Patrol and independent experts, we completed a detailed review of cable barrier in Marysville and across the state. Governor Chris Gregoire requested the report after a Feb. 13, 2007 fatal crossover collision on I-5 in Marysville. The report recommended replacing the cable barrier along northbound I-5 in Marysville with concrete barrier.
- Spring 2008 – The 2008 supplemental budget included $26.9 million to install concrete barrier along 10 miles of northbound I-5 in Marysville.
What makes Marysville unique?
As part of the July 2007 Cable Barrier Report, WSDOT engineers and independent experts reassessed I-5 traffic and safety data for Marysville. They found that there is no single reason for Marysville’s unique crash history. Overall, the collision rate in Marysville is lower than the statewide average. The report suggested that several factors need additional study:
- Speeds: Within this stretch of I-5, posted speeds transition between 70 mph and 60 mph. In addition, a significant number of drivers exceed speed limits in this area. One out of every 2,000 drivers – more than 1,000 every month – is traveling at more than 90 mph in this area. Of the 47 locations in the state where WSDOT has permanent traffic recorders, this area ranks fourth highest for speeding. In this area, faster drivers meet slower-moving traffic. This mix of speeds can lead to weaving, tailgating and other aggressive driving behaviors, and force other drivers into erratic, reactive driving.
- Interchanges and ramps: North of Arlington, interchanges and ramps are relatively few and far between. However, traffic on I-5 in Marysville enters and exits the freeway at many ramps: the Smokey Point rest area, SR 528 (4th St), 88th St NE, 116th Street NE, SR 531 (172nd) and SR 530. Many of these ramps carry a high volume of traffic, and traffic volumes have dramatically increased during the past several years. This increases merging and related maneuvers by drivers.
- Traffic volumes: Mirroring nearby residential and commercial growth, this section of I-5 has experienced dramatic traffic growth during the past 20 years. Traffic has roughly doubled.
- Urban meets rural: This 10-mile stretch of I-5 is often the northern boundary between free-flowing rural traffic and congested urban traffic in the greater-Seattle area. Not all drivers anticipate the change in traffic conditions as they enter this area. Nineteen of the 22 cross-median collisions and all of the fatal collisions in this area involved southbound vehicles crossing into northbound traffic. Nearly all of the most severe crashes occurred in the afternoon, which coincides with peak southbound traffic congestion.
What types of highway barrier does WSDOT use?
We use three general types of barriers: cable, guardrail, and concrete. Each barrier type is designed to protect drivers in different ways. No barrier can protect every driver in every situation.
How does WSDOT decide what type of barrier to use for each location?
Before installing barrier, we first determine whether barrier would enhance safety, and if so, which barrier type would work best at each location. Our engineers consider a variety of factors:
- accident trends and history
- community and driver comments
- traffic speeds and volume
- road grade, angle and curve
- available median and shoulder space
- slope of the median
- barrier characteristics
- installation and maintenance costs
Why is installing concrete barrier in Marysville so expensive?
Installing concrete barrier, widening ten miles of the roadway shoulder, and constructing drainage and stormwater treatment facilities all contribute to the high cost of this project. Concrete barrier itself is expensive to construct and install, averaging $150 per linear foot. Installing ten miles of concrete barrier will cost nearly $8 million out of the total project cost of $27 million.
Where can I find out about statewide cable barrier projects?
By the end of 2008, we will have installed about 185 miles of cable barrier in Washington state. Learn more about these projects on our statewide cable median barrier page.