Rural Safety News is an electronic newsletter of the Center for Excellence in Rural Safety (CERS) at the University of Minnesota. Rural Safety News brings you the latest research and resources concerning rural safety.
New research shows extended safety benefits of decision-support systems at rural intersections
A driver pulls up to a stop sign at the intersection of a busy rural highway. As cars and trucks whiz past at high speeds, the driver questions when to safely proceed onto the highway and how much space is needed to make the turn safely.
Sometimes these questions are hard to answer and drivers make the wrong decision. In fact, intersection collisions account for about 21 percent of all traffic fatalities. Rural intersections are especially dangerous due to high travel speeds. But what if technology could help these drivers make better decisions—saving lives in the process? That’s exactly what researchers at the University of Minnesota Intelligent Transportation Systems (ITS) Institute are working to discover.
Previously, ITS Institute researchers documented the immediate safety improvements of an intersection decision-support system known as the Cooperative Intersection Collision Avoidance System (CICAS). An electronic sign placed in the median of a rural road intersection shows drivers when a car is approaching the intersection and alerts them when the gap between their position and the oncoming vehicle is too small to safely enter or cross the roadway.
In their latest study, researchers examined how drivers adapt to the technology in the short term and whether the technology improves performance after drivers stop using it. The research was funded by ITS Institute, the HumanFIRST Program, and the Center for Excellence in Rural Safety.
“Most traffic safety technology studies look at performance over an hour, but in the real world that is never the case,” said Mike Manser, lead researcher and HumanFIRST program director. “It’s important to determine how drivers are going to respond to these systems over time. Do they adapt in positive ways, or, in the worst-case scenario, do benefits taper off over time?”
For this study, the sophisticated HumanFIRST driving simulator was used to create an exact replica of a rural intersection in southern Minnesota. Study participants “drove” through this intersection 12 times on five days. The system was inactive on days one and five and activated on days two, three, and four. Researchers compared results between the days the system was activated to learn how participants adapted to the technology. They also compared days one and five to see how use of the system affected driving behaviors.
The results show the promise of this technology. On the first day of use, drivers began rejecting smaller, less-safe gaps when entering the roadway. As they became more familiar with the technology, they became more likely to make better crossing decisions. When the system was turned off on the final day of the study, participants continued to reject less-safe traffic gaps.
“We hope this would translate into real-world drivers continuing to make good crossing decisions when the technology is no longer available or even when they go to a different intersection,” Manser said.
For next steps, researchers have begun two long-term CICAS studies in real-world situations. By enhancing the decision-making power of drivers and teaching drivers how to better negotiate potentially dangerous rural road intersections, CICAS researchers hope to save even more lives on our nation’s rural roads.
In an effort to improve safety on Minnesota roads, the Minnesota Department of Transportation (Mn/DOT) is partnering with the state’s 87 counties to develop individual county road safety plans, according to Mn/DOT assistant state traffic safety engineer Brad Estochen. Estochen was the featured speaker during a November 9 webinar, part of a series about best practices for rural traffic safety sponsored by CERS, in cooperation with the Federal Highway Administration.
Each county road safety plan is designed to identify the county’s areas of risk and institute strategies to reduce fatal and severe crashes. Estochen explained that the purpose of these plans is to distribute road safety funds to areas where fatal and serious injury crashes are occurring or are at risk of occurring on local roadways. Each plan will be completed over a nine-month period, with 20 to 24 counties in-process simultaneously.
The primary difficultly in developing the plans, according to Estochen, is that local road networks have more miles of road and fewer crashes per mile than the trunk highway system, making it harder to determine a county’s riskiest roadway areas using traditional techniques.
The traditional approach to risk identification, where “crash equals risk, and no crashes mean there’s no risk,” is not as effective for county roads because they don’t have many locations with multiple fatal and severe injury crashes, Estochen said. In one 3,000-mile county roadway sample, for example, Mn/DOT identified only nine “black spots,” or locations where two or more severe crashes have occurred in a five-year period. Seven of them were intersections with the trunk highway system.
The lack of black spots contributed to the Mn/DOT approach to develop the county highway safety plans, Estochen explained. Instead of looking only at crashes, the new approach treats roadway and traffic characteristics that contribute to fatal and severe crashes as surrogates. For instance, when considering the safety of a curve, crash surrogates include elements like the presence of an intersection or a visual trap. (A visual trap occurs when the county highway curves but there is another road on the tangent extended, usually a gravel township road.)
As part of the safety plan assessment, roadway segments that meet the criteria of a surrogate measure receive a star to indicate each risk. These star ratings determine high-risk areas of county roads as well as how funding is allocated and which safety strategies to apply. Mn/DOT uses strategies suggested by the National Cooperative Highway Research Program.
At the conclusion of the process, Mn/DOT will hold a safety workshop in each county to present crash data and assist the county in limiting safety strategies to a manageable number. Workshop attendees are allowed to vote on strategies they believe are important, and Mn/DOT considers the results when compiling the final version of the safety plans.
Thus far, county road safety plans have completed in Mn/DOT Districts 3 and 6, and Districts 4 and 8 are currently under way. Mn/DOT expects all counties to have safety plans in place by 2012.
One nation’s no-excuses approach to highway fatalities pays off in lives saved
A few traffic safety statistics are no different in Sweden than in the United States or elsewhere in the world. The Swedes estimate 85 percent of all traffic crashes are the result of human error. But while most people—and most countries—use this statistic to explain the inevitability of traffic fatalities, Sweden takes a far different approach.
“We believe we do not have the right to kill people for the sake of mobility,” said Swedish Transport Administration road safety expert Patrick Magnusson. “We forget about the ‘blame the victim’ approach and recognize it is our responsibility to take the necessary steps to prevent drivers from being killed or injured on our roads.”
This no-excuses safety philosophy was formalized by the Swedish government in 1997 when its parliament passed the “Vision Zero” initiative stating that no loss of life is acceptable on the nation’s roadways. The initiative centers on the idea that while humans will make mistakes behind the wheel and crashes will occur, the highway system should be designed in way that reduces injuries and prevents loss of human life.
Magnusson identified several “silver bullets” that have helped the country make large strides toward its goal of zero fatalities. One of those is a rural road safety tactic known as the 2+1 road. In the 1990s, hundreds of Swedes were killed and injured on the nation’s 2,200 miles of 43-foot-wide, two-lane roadways. These rural roads were some of Sweden’s most dangerous, accounting for 25 percent of severe-injury crashes even though they made up less than 4 percent of the total road system.
After searching for a low-cost way to improve the safety of 13-meter roads within the existing right-of-way, they settled on an innovative approach: the 2+1 road. In this design, the existing two wide lanes and shoulders are converted to three narrow lanes with a cable barrier down the centerline. The central lane alternates between traffic directions at regular intervals to provide ample passing opportunities. After years of discussion and debate, the first 2+1 road was built.
“Today, Sweden has more than 1,200 miles of 2+1 roads,” said Swedish Transport Administration road design strategist Torsten Bergh. “We’ve seen a 90 percent decrease in fatalities on our 13-meter roads and are saving more than 50 lives a year. The level of service has also increased, with drivers travelling at higher average speeds.”
With the Vision Zero initiative, the Swedish commitment to highway traffic safety is paying off in lives saved. Sweden is now a world leader in traffic safety. In 2008, it had just 4.3 highway deaths per 100,000 in population, compared with 12 per 100,000 in the United States. The country is equally committed to the global cause of traffic safety, sending experts around the world to talk about Sweden’s vision of a safer road system and help other governments adopt their own “vision zero.”
Roadway departure crashes are frequently severe and account for more than 50 percent of U.S. traffic fatalities. One cause of roadway departure crashes, particularly on rural two-lane highways, is vertical pavement-edge drop-offs. These drop-offs develop during paving or over the life of the pavement as aggregate and other material adjacent to the pavement settles or is worn away.
A typical pavement-edge drop-off-related crash occurs when the driver attempts an immediate return to the roadway but loses control of the vehicle as a tire catches on the edge of the pavement. Drop-off crashes usually involve a collision with a roadside object, a head-on collision, a rollover, or an opposing sideswipe.
“We do have a serious safety problem,” said Cathy Satterfield with the FHWA Office of Safety. “We’ve selected a few technologies that we think are out there ready to be installed and we’re going to push a little harder to try and move forward faster so we can get the benefits much sooner.”
One such paving technology, known as the Safety Edge, has been in development for almost a decade and is now part of the Federal Highway Administration (FHWA) Every Day Counts (EDC) innovation initiative. EDC is aimed at “taking effective, proven, and market-ready technologies and getting them into widespread use” to help “improve safety, reduce congestion, and keep America moving and competitive.”
The Safety Edge replaces vertical drop-offs during the paving process with a 30-degree slope at the edge of the pavement, allowing drivers to recover safely if they drift off the road.
The FHWA is working with states to develop specifications and adopt this pavement edge treatment as a standard practice on all new and resurfacing pavement projects. The preventive technology has been used on a limited or test basis in several states.
In October, FHWA partnered with Dodge County, Minnesota, the Minnesota Department of Transportation, and the Minnesota Local Technical Assistance Program to discuss and demonstrate the Safety Edge during a county road paving project. The event is just one example of a growing number of several similar events involving a mix of partners, including federal, state, and local agencies as well as industry, to share the safety solution.
A major challenge to widespread implementation of the Safety Edge, however, has been a lack of data about the role of edge drop-offs in roadway departure crashes. Available crash data often contain no clear, easily quantifiable indication of whether an edge drop-off was a factor in a crash. But a 2006 AAA Foundation for Traffic Safety study of rural paved roads with unpaved shoulders in Missouri and Iowa found that drop-off crashes were two to four times as likely to be fatal as all rural crashes. The same study found nearly a quarter of all roadway departure crashes in Missouri involved edge drop-offs.
Despite the limited data supporting the need for the Safety Edge, a small-but-growing body of experience with the technology has yielded positive results. “Because we have so few sections, and they tend to be on lower-volume roads, we don’t have a significant number. But everything seems to be better, and our best estimate right now is a 5.7 percent reduction in all crashes," Satterfield said at the Dodge County demonstration.
As a further benefit, the Safety Edge involves minimal time and cost to implement. It is installed during paving, using a special commercially available shoe that attaches to existing equipment in just a few minutes. The special paving shoe costs about $3,000. Typically, little or no additional asphalt is needed (less than 1 percent of the total project). The Safety Edge also has been used for concrete pavement edges.
Because the Safety Edge provides an additional compaction along the edge, it also improves pavement durability and contributes to longer pavement life. It can also help save contractors money during the paving process of some projects by reducing the need for traffic control and improving temporary access to detour lanes without extra paving.
Sue Miller, county engineer in Freeborn County, Minnesota, and past president of the National Association of County Engineers, has been an advocate of the Safety Edge since implementing the technology in response to a fatal crash in 2004 involving teens and a 2-inch edge drop-off. She characterized the Safety Edge as low-cost insurance against tort liability, especially for roads with hard-to-maintain shoulders and for roads with no shoulders.
To date, Freeborn County has paved about 65 miles of road with the Safety Edge. “There’s so much stuff going on in our cars today,” Miller said at the Dodge County demo. “We have to provide more of a safety net for drivers and safety-proof our roads.”
CERS director Lee Munnich participated in a panel discussion about the political dimensions of traffic safety at the annual Minnesota Toward Zero Deaths Conference in October. He talked about public support for rural road safety policies, based on data from the CERS National Rural Road Safety Public Opinion Survey.
Munnich also participated in a seminar immediately following the TZD conference about Sweden’s Vision Zero Initiative (see related story in this issue). At the seminar, high-level safety advocates and transportation officials from Sweden and Minnesota discussed ideas and practical solutions within their respective traffic safety strategies. Topics of discussion included how Sweden has changed the culture of traffic safety, how roads can be built cost-effectively and still minimize the fallout from driver error, and how Sweden’s approach to impaired driving differs from that of Minnesota.
The new Transportation Research Board (TRB) Joint Subcommittee on Rural Road Safety Policy, Programming, and Implementation is cosponsoring a rural road safety panel session with three committees at the TRB 90th Annual Meeting, January 23–27, 2011, in Washington, D.C.
The rural road safety panel session (#617), scheduled from 7:30 to 9:30 p.m. on January 25, 2011, at the Shoreham Hotel, will feature presentations on preliminary findings from a roadway departure domestic scan (Daniel Helms, Mississippi Department of Transportation), rural intersection treatments (Daniel Magri, Louisiana Department of Transportation and Development), international road assessment program activities on rural roads (Peter Kissinger, AAA Foundation for Traffic Safety), and development and implementation of comprehensive local safety plans (Howard Preston, CH2M Hill). The session also will be taped.
Another session (#144I), sponsored by the Committee on Vehicle User Characteristics, will focus on human factors and rural crash issues on January 23, 2011, from 9 a.m. to 5 p.m. at the Marriott Hotel. Expected speakers include former CERS director of transportation safety engineering Keith Knapp as well as Nic Ward, Sue Chrysler, Melissa Walden, and Gary Davis. The session, which will involve a multidisciplinary presentation and interactive case-study approach, is aimed at ongoing safety efforts like the national Toward Zero Deaths effort and others. Advanced registration for this and other Human Factors Workshops is recommended.
The first official meeting of the Rural Road Safety Policy, Programming, and Implementation Joint Subcommittee is scheduled from 10:15 a.m. to 12:15 p.m. on January 26, 2011, in room Virginia C at the Marriott Hotel. Knapp, now Iowa LTAP director, and Julie Skallman, director of State Aid for Local Transportation at the Minnesota Department of Transportation, will moderate the session.
The new joint subcommittee is the first entity to focus solely on the issue of rural roadway safety. The parent TRB committees of the joint subcommittee are Transportation Safety Management and Low-Volume Roads. The Committee on Transportation Safety Management will meet January 24, 2011, 1:30 to 5:30 p.m. at the Marriott Hotel. The Committee on Low-Volume Roads will meet January 25, 2011, 8 a.m. to 12 p.m., also at the Marriott. The Committee on Roadside Safety Design, which is a cosponsor of the rural road safety panel session, meets at the same time as the Committee on Transportation Safety Management.
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Center for Excellence in Rural Safety
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