Linda Poon is a staff writer at CityLab covering science and urban technology, including smart cities and climate change. She previously covered global health and development for NPR’s Goats and Soda blog.
When it comes to road markings, some experts say less is more.
In some parts of the U.K., the roadways are looking kind of bare. Markings that indicate bus and bicycle lanes remain, but gone are the white lines that separate opposing traffic. That may seem like a hazard, but according to some experts, the lack of centerlines can actually make roads safer by making drivers slow down.
In a 2014 report, the Transport for London (TFL) argued that while centerlines are standard, not all roads need them. They further noted that “most traffic engineers prescribe them by default without questioning the necessity.”
The agency is currently testing centerline removal on at least three roads with a speed limit of 30 mph, and the results so far show promise, according to the report. TFL found that drivers slowed down, on average, by five to nine miles per hour. Researchers also observed that speeds were particularly lower when drivers were passing oncoming traffic.
One theory is that by removing the centerlines, engineers make roads riskier, thereby replacing confidence with a sense of uncertainty. “[Center] lines and hatching can provide a psychological sense of confidence to drivers that no vehicles will encroach on ‘their’ side of the road,” the researchers wrote.
The thinking rests on the idea that perceived changes in risk and personal safety people influence behavior—what John Adams, a geographer at University College London, calls “risk compensation.” According to Adams, who studies risk management in the transportation sector and who isn’t involved with TFL’s study, everyone has a “risk thermostat,” set at each person’s natural tendency to take risks. That propensity is balanced by a number of things, namely the magnitude of the reward, the experiences of previous accidents as a result of taking risks, and our perception of what is safe or dangerous.
So safety measures don’t always lead to safer conditions. It may make drivers feel safer, which in turn could make them more inclined to be a bit more daring behind the wheel. Since the dividing lanes come with the expectation that drivers will stay in their individual lanes, for example, someone might hit the pedal just a little harder.
The opposite can also be said: “If you change the environment in a way that drivers, pedestrians, and cyclists perceive it to be more dangerous, then they will adjust their behavior and be more cautious,” Adam tells CityLab.
Adam points to a study looking at accident rates in Ontario in relation to the weather, which he details in his book Risk:
…[O]ver a ten year period in Ontario the number of fatalities was highest in August, when the roads are clear and dry, and lowest in February, when the roads are frequently covered with snow or ice. … Drivers appear to compensate for the hazardous conditions by slowing down, so that the accidents that they do have are much less serious.
Risk compensation, says Adams, is often applied to a hotly debated concept known as “shared space,” in which the safety of roads shared by bicyclists, drivers, and pedestrians benefits from having little to no traffic lights, signs, curbs, or roadway markings. The idea: When you have to pay more attention to your surroundings, you’ll use social interactions to determine right of way, and you’ll adjust your speed accordingly
But critics of shared space and centerline removal aren’t convinced. George Lee, the chief executive of the U.K.-based Road Safety Markings Association, told Transport Network that the approach was unproductive, adding that such schemes would “create a wild West.”
“There should be no uncertainty in the road environment,” he said. “Drivers should travel in a standardized environment where they know exactly what to expect.”
And speaking to the BBC, Neil Greig, the director of policy and research at the Institute of Advanced Motorists, said that the lines should remain an option to treat routes with a poor safety record.
Echoing the TFL researchers, Adams notes that removing centerlines isn’t a solution to all roads. “It wouldn't work on roads with a high speed limit and not many pedestrians and cyclists,” he says. “It depends on a mutual recognition on the parts of all the participants.”