by Ben Ross, Greater Greater Washington
Marlyn Eres Ali was killed last week in Wheaton, crossing Connecticut Avenue on foot at an intersection with no traffic light. She was in a crosswalk that has wheelchair ramps and a paved median refuge but no markings on the pavement. Why aren’t crosswalks like this one marked?
Crosswalk where Marlyn Eres Ali died. By permission of nbc4 news.
Legally, a pair of crosswalks exists at every intersection, regardless of whether there are markings on the road. Most of the general public believes that marking those crosswalks makes them safer to use. But the Federal Highway Administration disagrees. Sometimes, at least.
Its Manual on Uniform Traffic Control Devices or MUTCD, the traffic engineer’s bible, states that on roads with 4 or more lanes, speed limits above 40 mph, and heavy traffic:
New marked crosswalks alone, without other measures designed to reduce traffic speeds, shorten crossing distances, enhance driver awareness of the crossing, and/or provide active warning of pedestrian presence, should not be installed across uncontrolled roadways.
Local agencies, reluctant to make cars go slower and short of funds to install the pedestrian warning lights called hawk beacons, usually take this as an injunction to simply leave the crossing unmarked.
The MUTCD bases this provision on studies of crash data. Pedestrians crossing big highways, these studies report, have a greater chance of being hit by drivers at marked crosswalks than at similar unmarked ones.
There are several possible reasons for this.
- Traffic engineers often locate marked crosswalks at the places where they interfere least with vehicle movement. Pedestrians may put a higher priority on safety when choosing where to cross.
- Politicians may demand crosswalk markings at the intersections with repeated crashes, meaning the crashes are not a consequence of the marked crosswalk but the cause.
- Researchers have other suggestions, too, as Tom Vanderbilt discusses on page 198 of his book Traffic.
Whatever the causes of this phenomenon, if it is real, there is an easy way to save lives: FHWA and state transportation agencies could instruct pedestrians to ignore crosswalk markings when they cross highways without traffic lights. Cross at whatever intersection feels safest, not the one with a marked crosswalk.
Of course, you will never hear that advice in a safety campaign. They urge pedestrians, as the current DC effort puts it, to “always use a crosswalk.” Pedestrians understand this to mean a marked one, and the campaigns reinforce that belief with images of marked crosswalks.
FHWA safety poster.
The FHWA’s own pedestrian safety campaign does not explicitly recommend using marked crosswalks. But—somewhat like advertising for an escort service—what isn’t said matters more than what’s said. The text assumes that the reader already has an idea of what’s going on and carefully avoids correcting that impression. The real message is in the pictures.
Why would highway agencies promote pedestrian behavior that their research shows to be unsafe? One potential reason is that the traffic engineers don’t really believe the research. The study results are often inconsistent; the researchers offer many cautions. Scientists know that when you get a result contrary to common sense, it’s most often wrong. If it still stands up after checking and double-checking, you may have a great discovery, but more often you’ll find a subtle mistake buried in your work.
The other possibility is that safety isn’t really what this recommendation is about. Rather, it may reflect drivers’ desire, reinforced by the historic biases of the traffic engineering profession, to get pedestrians out of unmarked crosswalks where they slow down cars. Peter Norton has shown that safety campaigns, when they started in the 1920s, aimed to push pedestrians off the streets and make room for cars.
Intentionally or not, the traffic engineering profession gravitates toward conclusions that support its existing practices and priorities. When the research supports a road design that speeds traffic—wonderful! A safety recommendation that would slow down vehicles—unthinkable!
Continue reading “On crosswalks, research and safety campaigns conflict”
