A new report by the Insurance Institute for Highway Safety says some “relatively simple and inexpensive” changes could dramatically reduce the number of car crashes on urban and suburban roads, which kill about 8,000 people and cause more than 1 million injuries each year.
Motorists travel 2 billion miles every day on 150,000 miles of arterial roads in and near U.S. cities, the report says, a much heavier traffic load than most those roads were ever meant to carry. But major improvements are costly and disruptive, sometimes for long periods.
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Knowing that accidents don’t happen at random, however – they’re often at predictable spots, due to predictable traffic problems – Richard Retting, senior transportation engineer at the institute, set out to see how much he could reduce crashes with smaller-scale solutions.
Retting picked Leesburg Pike, a major artery in Virginia, in the suburbs of Washington, D.C., to demonstrate his idea. He and his team studied traffic on the road, identified frequent causes of crashes, then applied measures such as adding protected left-turn signals at problem intersections, extending a merging traffic lane, and moving a bus stop.
The results were “dramatic,” the IIHS reported: At two of the six locations where such measures were applied, the targeted crash types were reduced to zero. At four other intersections, crash rates were “significantly” reduced.
Behind the figures were small changes with a big impact on motorists. At one intersection, for example, cars used to have to cross several lanes of 45-mph traffic to turn left, and with low visibility to boot; now they have a protected turn signal – and no more crashes.
A merge lane extension elsewhere reduced rear-end crashes from an average of 8.2 a year to 0.9 a year. And by removing one bus stop and widening the shoulder at another bus stop, rear-end accidents in both locations were reduced.
“It’s a matter of studying urban arterials to pinpoint where crashes are occurring frequently and then identifying potential solutions, looking first for less costly measures that can be implemented more quickly than major re-engineering,” Retting said.
That’s definitely a strategy that the Rhode Island Department of Transportation is using, said Robert Rocchio, acting managing engineer for traffic design. The work is happening on two fronts, he said: the “accident reduction program,” which makes lane improvements and whatever else is needed to reduce crashes in particular spots, and the “traffic signal optimization” project, in which contractors are hired to do smaller-scale upgrades.
In the latter, a “quick-and-dirty” approach to traffic improvements, extra traffic signal heads may be added, along with back plates to increase the lights’ visibility. Left- or right-turn signals may be added, and the traffic signal controllers are upgraded so they can respond to different traffic patterns throughout the day. DOT now has a contractor doing this with 20 intersections in northern Rhode Island, he said.
“We can get there, make changes quickly, and get a big bang for our buck,” Rocchio said. The cost averages about $25,000 per intersection, he said, “which is a relatively low cost for the benefits you get.” Adding lanes and otherwise overhauling an intersection, by contrast, costs an average of $100,000 to $200,000, he said, and can take several years.
