by Henry Apfel July 1st, 2012
Data from the Washington State Department of Transportation show that over the past decade there’s been a significant downwards trend in The Evergreen State’s total vehicle collisions and fatalities, even with an uptick in vehicle miles travelled. Additionally, the number of accidents per 100 million miles travelled has dropped sharply, as has the death rate. From 2002 to 2010, vehicle miles traveled increased by four percent – less than a fifth of a percent higher than nationally over the same time – while the number of collisions dropped 10.5 percent. Collisions per 100 million miles traveled declined 19.3 percent. There were 43.4 percent fewer driver fatalities in Washington state in 2010 compared to 2002, and given the increase in miles traveled, driver fatalities per 100 million miles in Washington state decreased 53.5 percent from 2002 to 2010. National Highway Traffic Safety Administration data show that his contrasts with a drop in the comparable U.S.-wide rate over the same stretch of 26.5 percent.
We’ve created an original visualization of the data below using the free Tableau Public tool from Seattle-based Tableau Software. We also get an analysis of the data trends from a University of Washington transportation expert.
Data visualization instructions: a) Start with the “Collision and Fatality Trends” tab view, to see color-coded data key. b) Run your mouse along lines to see individual points of data. c) You may also select different tabs for other representations of the information.
(Note: The original data included a category called “Miscellaneous Roadways” that was omitted for the purposes of this article. Consequently, total values are slightly different from the original data. Source: Washington State Department of Transportation Table TT03 on Road Usage and Safety, found in The State of Washington 2011 Databook, January 2012, Office of Financial Management)
A range of factors likely explain the decline in vehicle fatalities and accidents in Washington State, although their relative importance is difficult to determine, said Professor Mark Hallenbeck, Director of the Washington State Transportation Center at the University of Washington. One “has been a big push by USDOT (and consequently the state DOTs) to reduce the number of road fatalities,” he said. Hallenback also cited growing safety improvements to vehicles, “click-it or ticket” programs which enforce the use of seatbelts, and graduated driver licensing laws that allow young drivers to gain experience in a safe environment prior to being fully licensed. He added that many roads have had safety improvements, such as the addition of median barriers where there were none previously.
Other factors figure in, as well. Use of digital devices while driving is a known risk factor but hard to quantify. One study by the Virginia Tech Transportation Institute suggested that dialing a hand-held wireless device increased the risk of a crash or near-crash by almost three times.
Related: Q&A with Professor Mark Hallenbeck, Director, Washington State Transportation Center, University of Washington