Friday, September 19, 2008

Cable median barrier continues to save lives

This week we released the 2008 annual report on cable median barrier in Washington State. The report is a follow up to the June 2007 report requested by Governor Chris Gregoire.

How is cable median barrier performing? Well, there’s good news and more good news. Cable barrier continues to save lives in Washington. Statewide, cable barrier successfully restrained 95 percent of vehicles from crossing highway medians.

Additionally, in areas where cable barrier has been installed, there has been a 73 percent reduction in serious injuries and fatalities from crossover collisions. While no barrier can protect drivers 100 percent of the time, drivers who strike cable median barrier are less likely to be seriously injured because the cable barrier absorbs the force of the collision. Vehicles that hit the rigid concrete barrier are more likely to ricochet back into traffic. Occupants are at risk of suffering injury from the force of impact with the rigid barrier and from colliding with other vehicles.

So if cable median barrier is so great, why is WSDOT replacing 10 miles of it with concrete barrier in Marysville? Last July, WSDOT, the Washington State Patrol and independent experts completed a detailed review of statewide cable median barrier and cross-median collisions on I-5 in Marysville at the request of Governor Gregoire. The report noted a higher-than-average number of crossover collisions on I-5 in Marysville, for reasons not completely understood by safety specialists. Due to the history of cross-median collisions in this area, the report recommend installation of concrete barrier on the northbound inside shoulder of 10 miles of I-5 through Marysville while leaving the existing cable median barrier adjacent to the southbound lanes. Using both cable median barrier and concrete barrier will help keep southbound traffic from crossing into the northbound lanes.

You can find more about the 2008 Cable Barrier update at:


Anonymous said...

Cool stuff. I'm guessing cable median barrier is cheaper and more environmentally friendly than concrete median barriers, too?

Anonymous said...

No no no no NO! WHY CABLE BARRIERS? Has WSDOT not realised that many countries have been BANNING cable barriers? The United Kingdom used to adore cable barriers like WSDOT is now, but not anymore. Ask why?

Because a motorcyclist in Scotland got sliced in half falling off on a cable barrier. A motorcyclist in New Zealand suffered the same fate.

If WSDOT is to endorse a barrier, it should place motorcycle safety at the top. May I suggest double metal barriers?

With some vegetation in the middle, these barriers are not only functional and sturdy, but also pleasing to the eye. Depending on where you are, these are called B-profile barriers.

Here's a cutout:

Before overpasses, a combination of our current metal barriers and a separate type of barrier would be nice. Like this:

Wayne Dyck said...

(on behalf of Dave Olson)

WSDOT is very much aware of the concern over motorcyclists striking cable barriers. As we evaluate these issues, we want to ensure our decisions are based on accurate facts. We've learned that there is some misinformation on this topic as well as some very real trends in motorcycle safety. The increase in the number of motorcycle deaths over the past few years is a trend that the WSDOT is very concerned about and we are working to reduce the frequency and severity of those collisions.

Clearly motorcyclists are at a greater risk of injury in a crash with any type of barrier because they do not have same protection provided by seat belts, airbags, and vehicle framework. Our review of motorcycles hitting various barriers, reveals that there is no significant difference in injury severity for the various barrier types. During 2007, there were four motorcycle collisions involving cable barrier. In most of these events there is doubt that the rider ever reached the cable barrier system, although the motorcycle itself did. In one of these collisions it is clear that the rider was on the motorcycle when it contacted the barrier. In this case, the rider suffered arm abrasions. We also know of a fatal collision in June 2008 where a motorcyclist contacted the barrier. In this event, the rider was traveling at a high rate of speed and was using both shoulders to pass vehicles when he lost control and struck the cable barrier. We are working with the responding officer to get a better understanding of the nature and specific cause of injuries in this collision.

In contrast, we are also aware of fatal collisions where cars or trucks crossed the median and collided with motorcycles in the opposing lanes. Median barriers reduce the potential for motorcyclists to be struck by vehicles departing from the opposing traffic lanes. Reducing collision severity require attention to all the potential sources of collisions.

We have heard that one European country has banned the use of cable barrier, over complaints from motorcycle users. What is not clear to us is whether the ban was implemented as a result of actual crash experience or over fear (perception) of what might happen. A 2006 study in New Zealand published a paper that concluded "...whilst WRSBs [wire rope safety barriers] have the potential to cause serious injury to errant riders, so do all road safety barriers." They went on to say "there is no reliable evident to indicate the WRSBs present a greater risk or less risk than other barrier types, or indeed, no barrier at all." In January 2008, an international meeting of the Transportation Research Board was convened with a focus on motorcycle safety. There were at least 15 presentations on motorcycle safety. Cable barrier was discussed, and this committee concluded that "there is no clear proof that cable barrier systems are cheese cutters."

The bottom line is, we need more information to help us determine what is happening with motorcyclists and roadside barriers. To help separate fact from fiction and to gain a better understanding of this issue, WSDOT proposed national research through the Transportation Research Board to evaluate the "Factors Related to Serious Injury and Fatal Motorcycle Crashes with Traffic Barrier." That new research project is now moving forward, and WSDOT is participating on the research panel, so that we can ensure that we are keeping abreast of methods to improve safety for motorcyclists.

Dave Olson
WSDOT Design Policy, Standards
& Research Manager

Anonymous said...

Hey wow could WSDOT answer my question too?

Why does WSDOT use outdated metal barriers with wooden supports instead of more modern ones utilised in European countries?

I am talking about guardrails such as these:

You can select the type of guardrail on the left navigation bar.

Wayne Dyck said...

(on behalf of Dave Olson)

Regarding the question from "Anonymous" about barriers used in European countries, the short answer is, the product is not offered for sale here, and we don't know if the barriers would meet safety crash-test requirements.

The roadside barrier products on this website appear to be developed and distributed through PRINS Dokkum, a company based in the Netherlands. While it appears that their products are for sale abroad, I find no evidence that they are offered in the United States. The competitive market normally leads product vendors to promote their products within a given geographic area.

The Federal Highway Administration (FHWA) offers a service that approves new products, such as barriers and other safety devices, for use on the National Highway System. Here in Washington, as in most other states, we rely on FHWA's approval letters as evidence that a specific safety product has successfully passed national crash-testing requirements. It is up to the vendors to get their products approved, as the crash testing and evaluation costs tens of thousands of dollars. I find no FHWA approval letters for PRINS Dokkum products in the US. I should point out that there are crash test requirements in others countries as well, and on the international scale there are efforts underway to make the criteria more uniform. It's probable that this system has proven to be crash-worthy through some evaluation criteria.

Although WSDOT tries to keep abreast of new technologies, there is a fair amount of responsibility on the product vendors to get their products approved and marketed to the states. After that, the competitive market tends to govern which products actually are used. Installation decisions are often based on a particular need, the initial product cost, repair costs, and product availability.

Thank you for your question and your interest in keeping us aware of alternative products.

Dave Olson
WSDOT Design Policy, Standards
& Research Manager

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