When Washington State transportation officials looked at highway crash data seven years ago, they were struck by how many accidents could be prevented with a relatively cheap improvement to their roads. Adding center-line rumble strips — which warn drifting drivers that they are crossing over into the opposite lane — turned out to be one of the most cost-effective ways to reduce crashes.
Like most places, Washington has long used rumble strips along the shoulders of interstate highways and some rural routes. In 1995, the state Department of Transportation first experimented with them in the middle of the road as well. After a review in 2004, it stepped up the use of them dramatically.
The numbers, says Dave Olson of the Washington State Department of Transportation, were "eye-popping."
Washington's experience with rumble strips is just one instance of how states are using data to make decisions about ways to spend money on transportation. But a study released Wednesday shows that they do this much better in some categories than in others.
The study , released by the Rockefeller Foundation and the Pew Center on the States ( Stateline's parent organization), concluded that when it comes to safety, all states do a solid job of collecting performance data and putting it to use. They consistently take into account information on crashes and fatalities when they design and improve highway facilities.
But in areas such as economic development and environmental stewardship, most states are only beginning to learn how to employ performance measurement to enhance the quality of their transportation programs. Only 16 states received high marks in using transportation data to benefit environmental stewardship; the same small number drew high grades in using it for economic development. All the other states either received middling grades in these categories or trailed behind.
"By almost any measure," the report says, "safety is the area in which states are doing the best job of measuring performance and responding to results."
What's remarkable is how much benefit states can accrue in the safety field without incurring very much additional cost. The Washington State rumble strips are a perfect example. In 2004, the state had about 100 miles of experimental center-line rumble strips; now 1,400 miles of highway have them — nearly half the state's highway system.
he grooves in the pavement are especially effective on rural two-lane roads, where vehicles travel at high speeds but are not separated from oncoming traffic with barriers or medians. The rumble strips generate sounds and vibrations easily noticeable to the drivers, who can then steer their vehicles back into the proper lane. When the strips were first installed, officials hoped they might reduce the number of crossover collisions by 15 percent. The actual reduction was three times as high.
The strips are "an effective, low-cost, low-maintenance countermeasure that significantly reduces the frequency of collisions," concluded Washington State researchers during a thorough examination of the devices released earlier this year.
Federal incentive One reason why states scored so well in using data to promote safety initiatives is that federal law all but requires them to. Under a 2005 law signed by President George W. Bush, states must look for ways to reduce crashes and fatalities on highways. Plus, states have joined federal efforts in other areas, such as cracking down on drivers who do not wear seatbelts or who use telephones while driving. Traffic deaths nationally have continued a decline that began back in the 1990s.
Rumble strips are especially effective because they prevent crashes that are disproportionately deadly. Accidents in which a vehicle leaves its lane cause most of the traffic deaths in this country, even more than collisions at intersections.
And that is not because there are more of them. It is just that the relatively small number of crossover crashes results in high numbers of deaths. In a recent four-year period in Washington State, for example, center-line collisions made up only 2 percent of Washington's crashes but 11 percent of its auto deaths.
The accidents are the results of many causes. In bad weather, drivers cannot see lane markers through snow or fog. Other drivers are distracted, drunk or sleepy. After installing center-line rumble strips, Washington saw the numbers of cross-over accidents fall even when drivers were fatigued, distracted, intoxicated or speeding.
Many states besides Washington have pushed for more center-line rumble strips, often with similar benefits. Among these are California, Colorado, Delaware, Maryland, Michigan, Minnesota, Nebraska, Nevada, New York and Wyoming.