Reminder: Cars are Exponentially More Dangerous than Bikes

Photo by Peter Krupa.

GM is often advocating for improvements to our infrastructure to make biking easier and safer. But inevitably when the topic comes up, someone always (ALWAYS) starts complaining about how cyclists break the law. They argue that until cyclists start obeying the law they do not deserve to be rewarded with more road space being dedicated to them. Oh, and a new one GM has heard is that we should not make any improvement that might induce more people to bike through the side streets of Georgetown.

This is infuriating on several levels.

The first is that multiple studies have shown that cyclists do not break the law any more than motorists do. It’s just that drivers ignore their own law breaking and notice the law breaking of cyclists.

The second should be obvious, but unfortunately gets ignored in the whataboutism: cars are exponentially more dangerous than bikes.

Just last Sunday a driver ran into a pedestrian in the crosswalk on K St. in Georgetown (above). And on Tuesday a driver plowed down four pedestrians on the sidewalk at 9th and New York Ave., downtown. A man died this week as a result of a driver running him over earlier this month at Missouri Ave. and 7th St.But those are just anecdotes. How about some clear data.

Let’s just consider the inherent danger involved in the operation of a car vs. a bike. There are many complicated ways to calculate the force impact of various collisions, but a simpler calculation is to simply compare the kinetic energy of a car vs. a bike. That’s a measure of how much energy the road user is bringing into a collision, the more energy, the more likely the pedestrian being struck will be seriously injured or killed.

Kinetic energy is calculated as mass x velocity² / 2. The unit is Joules. Here’s how an average sized car (1814 kg) going 30 mph (13.4 m/s) compares to an average sized cyclist (plus the weight of the bike) 100 kg going 20 mph (8.94 m/s):

The car goes into the collision with 162,860 Joules of kinetic energy. The cyclist comes in with 3,996. These aren’t remotely similar. Sure, brakes and engineering can limit the force delivered by the car to the pedestrian, but it enters the equation with 40 times the energy that it has to somehow divert away from the pedestrian’s body.

Yes, cyclists can nonetheless seriously injure of kill a pedestrian. But it’s extremely rare. Typically the injury comes from hitting the ground, not the cyclist. And plenty of everyday things can also cause falls, like for instance our brick sidewalks. They are far, far more likely to kill an elderly pedestrian than any cyclist would. Should we rip them up?

If pedestrian safety were truly the cause that animated most people objecting to improved biking facilities, than they would be doing far more to limit the danger from cars. But they typically don’t.

It’s never really about pedestrian safety. If pedestrian safety were really the concern, than slowing down drivers would be steps 1 through 99. But the moment a solution causes even a scintilla of added traffic, the pitchforks come out and the solutions are ripped out. Just look at the lane changes up in Glover Park a few years ago. Nobody cares about pedestrian safety if a five minute drive becomes an eight minute drive.

And it’s never really about lawlessness. Nobody ever complains about how much motorists break the law when it comes time to fill potholes. Group punishment is reserved for cyclists.

It’s time for that to stop.


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4 responses to “Reminder: Cars are Exponentially More Dangerous than Bikes

  1. A win-win for both cars and bikes would be to make most of the north-south streets in the east village one way. Like 33rd and 34th, one way streets allow for parking on both sides, a bike lane, and an easy flow of traffic (as opposed to the daily game of chicken on those streets now,) How about it East Village?

  2. jad6504

    Great graph, and responsibly explained (that this is the kinetic energy; still, very suggestive of the difference in the experience of getting hit by each). A dangerous bicyclist is largely a danger to himself. Not so much for drivers.

    Bicyclists suffer from an outgroup bias for most people. Bad behavior by cyclists is remembered by drivers; bad behavior by fellow drivers gets disregarded as unrepresentative of the group. They don’t know they’re doing it. If you identify with both groups, you notice that both regularly do dumb things, but as you point out the consequences to others are vastly, dramatically different.

  3. Pingback: The Hill is Home | TOMORROW: WABA-Organized Rally for Streets that Don't Kill People | The Hill is Home

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