Road Management & Engineering Journal
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Traffic safety people talk about the "three E's" engineering, education, and enforcement. By focusing on the first E, AAA Michigan has used relative[ly] inexpensive [methods] to dramatically cut crashes at problem intersections.
"It started from a conversation with our former CEO, Ron Steffens, and Dennis Archer, the mayor of Detroit," explains David Feber, Transportation Engineering Manager for AAA Michigan. "Mayor Archer complained that insurance rates were far too high in the city of Detroit; we looked at the data and agreed." Detroit's crash rates were double those in the rest of southeast Michigan, so AAA began working with the city to change that. A partnership was formed with the Michigan Department of Transportation, the City of Detroit, the City of Grand Rapids, Wayne County, the Southeast Michigan Council of Governments, Wayne State University, and the Michigan Office of Highway Safety Planning, to identify and upgrade problem locations.
The model was a project funded by the insurance company in British Columbia, Canada. AAA Michigan insures 22 percent of Michigan motorists, more than any other company in the state, so it also has a strong financial incentive to improve safety and cut claims.
AAA's engineers worked with city officials in Detroit and Grand Rapids, along with state and county governments in the target areas. Engineers identified high-crash intersections from state policy crash data and insurance records. Consultants studied the problem areas, designated the projects, and estimated the cost. The goal for AAA was a two-to-one direct benefit in three years in other words, the club would recoup its money in a year and a half because there would be fewer insurance claims at that intersection.
BIG RESULTS FROM SIMPLE FIXES
The program has produced astonishing results: During the first 27 months of the four demonstration projects in Detroit, crashes decreased by 47 percent, with a 50 percent reduction in injuries. "The interesting part of the program is that most of these very large crash reductions have been done with low-cost projects," Feber says. "You don't have to spend a million bucks."
The first few intersections cost approximately $35,000 each -- chump change compared to most traffic infrastructure improvements. And as you might expect from the relatively low cost, most of the intersection improvements are simple. "Typically, we upgrade," Feber says. For traffic lights, "We go from 8" to 12" lenses so they're 50 percent larger. We restripe left turn lanes with pavement markings, retime the traffic signals, and add something called an all-red clearance interval, where you leave both sides red for a second or two while the signals are changing." Intersections also get better signs and improved pedestrian signals, and parking that can block drivers' ability to see oncoming traffic is eliminated.
AAA's contribution of $1.5 million seed money generated funding of $14 million from Federal, state, and local sources. Feber stresses that the revamped intersections are intended as demonstrations: "We can't re-engineer all the intersections, nor should we. We're hoping to transfer this model to road authorities throughout the state to replicate these same principles." The City of Detroit has already asked for help identifying their high-crash locations, and Feber hopes other jurisdictions will also re-engineer problem intersections.
"The biggest savings is really from a societal perspective, from the reduced injuries," Feber says. "As the severity of an injury gets worse the insurance costs get less and the societal costs get higher." The estimated societal savings of the AAA seed projects is $100 million, Feber says.
REDUCED RED LIGHT RUNNING
To Feber's surprise, redesigning the intersections also reduced red-light running. "Interestingly enough, we've seen red-light violations decrease by approximately 50 percent," he says. Feber explains that "the larger signal heads are more visible, and we've placed them in more conspicuous places. What we're finding is that not all motorists are running red lights because they are aggressive. Some are running the light because they're not paying attention." Retiming the amber phase also helped: "You have to decide to stop when you see the yellow, Feber says. "So there's an optimal length of the amber phase where people can make that decision safely. If it's too short or too long you get more red-light violators."
Feber thinks that an engineering safety audit should be conducted before installing red- light cameras. "We have to make sure that the motorist has every fair chance of stopping before we ever put up a camera. Some intersections are designed so motorists tend to violate the red we can reduce that through engineering rather than enforcement."