Online Newsletter of the UC Berkeley Traffic Safety Center: Volume 3, No. 2, Summer 2006
Walking the Walk
An Interview with Pedestrian Safety Expert Charles Zegeer
One of the experts invited to address the Transportation Safety Seminar during the 2005-2006 academic year was Charles Zegeer, Associate Director of the University of North Carolina’s Highway
Safety Research Center and director of the Pedestrian and Bicycle Information Center. He has written numerous reports, including How to Develop a Pedestrian Safety Action Plan for the Federal Highway Administration, and has a long resume of accomplishments in the field (see sidebar).
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One of his recent projects for the Federal Highway Administration is developing a Pedestrian and Bicycle Safety Index, which will allow city engineers to identify dangerous areas for pedestrians before problems occur. It is part of a larger federal effort to improve conditions for bicyclists and pedestrians to encourage more physical activity and decrease use of cars and other motorized forms of travel.
Pedestrians and bicyclists suffer a disproportionate share of traffic fatalities, when measured as the share of travel done on foot or bicycle. Though the latter figure is difficult to estimate with great accuracy, it is generally accepted that walking and cycling trips comprise no more than nine percent of overall trips, yet pedestrians and cyclists account for 12 percent of the deaths each year from traffic crashes (some 4,000), in addition to an estimated 80,000 injuries. Calculated as a function of miles traveled, since this type of trip is much shorter than typical car trips, the danger is even more pronounced.
A federal goal of doubling the current 9 percent share of biking and walking trips makes pedestrian and bicycle safety improvements all the more compelling.
With a federal goal of doubling the share of biking and walking trips (as overall trip rates rise even faster), there is accompanying interest in making this type of travel safer. To achieve these goals, the FHWA has embarked on research efforts on a number of fronts, chief among them better understanding and estimating of pedestrian (and often, by extension) bicycle behavior. Because the emphasis on safety research has historically been on crashes involving motor vehicles, and because the number of non-motorized trips is not very well-known, this is proving to be especially challenging.
The Safety Index that Zegeer is developing is one such element. It helps correct for assumptions made in the past that emphasized street and intersection designs tailored to the goal of pushing more vehicles through a road network in less time.
Another element is pedestrian and cyclist and driver behavior, which is crucial to understand, but difficult to measure.
Zegeer discussed these questions in the following interview with staff at the Traffic Safety Center:
Q. Why do we need a Safety Index?
A lot of agencies would routinely only identify sites that had a cluster or a number of crashes at each intersection. Because of the relative infrequency of pedestrian crashes at any given site, it often meant that pedestrian and bicycling problems and needs were largely ignored.
In addition, a Safety Index could help engineers see the unseen as far as where the dangers might be, by helping identify intersections that are discouraging pedestrians from using them. Many are wide and have a lot of traffic moving in multiple lanes at high speeds, so pedestrians are afraid to cross. And because they are afraid to cross, crashes involving pedestrians are rare. So there is no way to identify those sites as being in need of treatment to make them safer for pedestrians.
Q. You have been studying intersection safety treatments that are low-cost?
Yes, it's a three-year study with the Texas Transportation Institute funded by the FHWA, where HSRC (UNC Highway Safety Research Center) is a sub-contractor to them. There may be information that comes from the study that might find its way into the Manual on Uniform Traffic Control Devices, as well as sites like yours. We may be evaluating things like the effectiveness of pedestrian countdown signals, or motorist-yield signs in the street, or advanced stop lines which helps with multi-threat conflicts.
To avoid one of the more common crashes, where a pedestrian is struck by a second vehicle in a crosswalk, advanced stop lines for cars could be used.
This is where we have a multi-lane road with two or more lanes in each direction in front of a marked crosswalk. As the first vehicle stops, it blocks the sight of pedestrians and oncoming vehicles in adjacent lanes. The pedestrian steps in front of the stopped vehicle and then into the path of an oncoming vehicle and there’s a collision. But if you move the stop line back, the stopped vehicle doesn’t block views of nearby pedestrians who might otherwise go unseen. The pedestrian has more time to stop or step back.
So something as simple and low-cost as advanced stop lines with signs saying "yield here for pedestrians" may help reduce multiple-threat crashes, even though there’s been a limited amount of studies to look at behavior. Part of the difficulty in this whole field is that we’re dealing with human behavior. We’re not robots, and everyone has his or her own behavior. Also, you and I don’t behave the same every day. We may be tired or distracted.
That is why the Traffic Safety Center’s Pedestrian Survey study is so timely. With all the national research that’s going on around technologies to support decisions made in intersections, very little has focused on trying to quantify pedestrian and bicyclist behaviors in crosswalks.
It’s difficult and it’s expensive to collect. Even though you can observe behavior to some extent, you can’t know all the time whether a pedestrian has really been searching for cars. You may see a head turn, but you can’t see the eyes of the pedestrian. You don’t know whether he or she is paying attention or distracted, and you certainly don’t know what’s going on with the driver. You can monitor speeds and brake lights and yielding behavior but there’s really only so much you can do from a particular standpoint with the standard techniques. So it’s difficult, it’s costly and that’s even if you can collect things like conflict and bad behavior. We don’t really know much about the relationship between behaviors and ultimately crashes.
Q. Has the increased funding and research for pedestrian safety translated into increased consideration for pedestrians and bicyclists in transportation engineering and planning instruction?
Certainly with planning schools. I know in the planning school at [University of North Carolina at] Chapel Hill there’s been a lot of emphasis on pedestrian and bike issues. There’s student demand at the university level for bike courses to be taught, and the faculty has been willing and very eager to comply with that. Probably a little less so in engineering, but I think that the engineering professors are trying to incorporate more information to students on walking and biking facilities.
Q. You went to Europe two years ago as part of your evaluation of low-cost treatments for pedestrian and bicycling conflicts study for the FHWA. What did you find there?
We can learn some valuable lessons from them, but they don’t have a lot of answers either. One thing that was interesting were automatic pedestrian detectors that use pressure sensitive materials that sense your weight and activate the signal to switch to walk. We do know pedestrians only push the button about 50 percent of the time. Having automatic detection of people at signalized locations takes care of those people.
There's also a smart signal that’s a red light camera with an advance loop detector in the pavement that tells when that vehicle is going to run a red light because of the speed of the vehicle and the distance back. Then it sends a call to the signal to hold the red light on the side street. In other words, not only do you get a picture of the guy running the red light but you can prevent a potential collision.
One of the main lessons we learned is that the Europeans have really learned how to use the carrot and the stick. The carrot is that they build nice pedestrian and bicycle facilities: sidewalks, bike lanes, separate paths, bike signals and bike lockers to make it enjoyable. The stick? One example is downtown Frankfurt, which is tearing down the biggest parking deck in town. They're going to reduce parking so people have to take the transit or walk or bike.
I don't hate cars. I enjoy driving my car, especially for longer trips, but I believe there’s real value in providing safe and convenient ways for people to bike and walk. It's about options.