Mostly to turn or because the signal doesn't recognize them, according to the latest research.
This past weekend Randy Cohen, former author of the "Ethicist" column in the New York Times Magazine, wrote an op-ed for the paper in which he admitted with pride to running red lights. Although the action is illegal, Cohen considers it ethical:
I roll through a red light if and only if no pedestrian is in the crosswalk and no car is in the intersection — that is, if it will not endanger myself or anybody else. To put it another way, I treat red lights and stop signs as if they were yield signs. A fundamental concern of ethics is the effect of our actions on others. My actions harm no one. This moral reasoning may not sway the police officer writing me a ticket, but it would pass the test of Kant’s categorical imperative: I think all cyclists could — and should — ride like me.
Cohen is certainly not alone. Studies in Brazil have found that nearly two in five bike riders infringe on red light laws. In China that figure is closer to 56 percent. So far researchers have failed to connect the behavior with increased crash rates, but it's been noted as among the most bothersome behaviors to others on the road, and a key contributor to negative portrayals of bike riding by the media.
So why do riders do it? A group of Australian researchers recently posed that question to roughly 2,000 people — many concentrated near Monash University, in Melbourne — in the form of an online survey. In an upcoming issue of the journal Accident Analysis and Prevention the researchers cite three main reasons for the behavior: the need to turn, the failure of a signal to recognize them at an intersection, and the absence of others on the road.
All told the survey found that roughly 37 percent of cyclists in Australia had committed a red-light infringement. About a third of this group said they ran the red to turn left. (In Australia, as in England, people drive on the left, so a left-turn in this survey is equivalent to going right on red in the United States.) About a quarter infringed because the light never recognized their presence at an intersection and therefore remained red unnecessarily.
A little more than a quarter said they ran reds, like Cohen, because no one else was around—with about 17 percent saying they keep going through a signal when there weren't any cars on the road, and about 11 percent saying they do the same in a crosswalk if there aren't any pedestrians. Only a few respondents said they did it because they thought it was safe (4 percent) and very few said they always ran reds regardless of the situation (less than 1 percent).
The researchers made some other connections of note. Male cyclists were 1.5 times more likely than females to have run a red, and younger people (those 18 to 29) were more likely than older riders. There was a noticeable link between infringements and accidents — riders who'd been involved in a bike-car crash were more likely to have run red lights — though the survey couldn't show any causal relationship. Some people seem to disregard red lights no matter their transport mode: survey respondents who'd been fined for a red light violation while driving in the past two years were much more likely to have infringed on a bike than those without a violation.
Knowing why riders run lights suggests potential improvements to a city's traffic organization. Permitting riders to turn right on red (or left, depending on the country) and painting areas where cyclists should stop to activate a signal cycle might increase compliance with the law and also improve travel time. The latter, in turn, would make bike riding more attractive, which could increase the number of riders. Research has shown that more riders on the road actually makes cycling safer.
As for breaking a law you don't agree with, readers are left to decide for themselves whether Cohen's actions are indeed ethical. Sure, some riders will exercise great judgment and save time. Then again others will make poor decisions and create more confusion (and, toward bike riders, resentment) than already exists on city streets. Some traffic laws may be inefficient or just plain wrong, but letting everyone on the road decide which ones to honor doesn't seem all that right.