Monday, June 7, 2010

Why bad things happen to bikes on the right

What ties together the three recent car/bike crashes? In each case, the biker was passing stopped (or nearly stopped) traffic on the right. It's not a coincidence. Ironically, traveling along side stopped traffic may be the most dangerous place for a biker to be.

Among bike advocates, it's already well-established that creating bicycle accommodations to the right -- parallel on-road* facilities --create some risks. It's counter-intuitive, but the risks are greater when the traffic is stopped. Put another way, moving traffic to the left provides some protection to bikes on the right.

There are five major dangers on the right:

  • Dooring -- the driver or a left-side passenger opening a door into a cyclist causing a direct injury or knocking the cyclist into traffic
  • The right hook -- a driver going in the same direction turning right across a cyclist, cutting the cyclist off
  • Crossing -- From the right or left, crossing over the lane and the cyclists' path to turn left
  • Merging traffic -- From the right, pulling into the cyclist's path
  • Crossing pedestrians

Traffic moving along on the left discourages or prevents all of these (one assumes inadvertently) bike-unfriendly behaviors.

Drivers and passengers exiting from the left pay more attention when they are opening a door into a lane of moving traffic. The faster traffic is going relative to bikers, the more likely a biker will be ahead of the driver turning right and visible to him before the turn, reducing the likelihood of right hooks. Drivers -- and pedestrians -- are unlikely to cross moving traffic and will be more careful merging.

Drivers and cyclists alike need to understand the special risks of bikes moving to the right of stopped traffic. Drivers need to understand the potentially fatal consequence of standard maneuvers in or across stopped traffic and to be on the lookout. And, cyclists need to be even more vigilant when traffic is slow or stopped, slow down a bit, and be especially careful when going by a gap in traffic.

It's not an answer to say bicyclists shouldn't pass on the right**. Many people are not comfortable riding in traffic when traffic is going at a bicyclist's clip. It's not reasonable to assume that either cars or bicycles will proceed at the lowest common-denominator speed. It's why the law allows bikes to ride on the right and cars to pass bikes in the lane, when safe and possible. As a policy matter, we want bicyclists to enjoy the benefit that accrues from having a small footprint that allows them to operate in a narrow lane and avoid traffic.

So, we all have to get better about what it means for bikes to pass on the right. When cars are slow, everybody really, really needs to pay attention!

*I address here parallel, side-by-side accommodations like bike lanes or striped shoulders. But, there are also parallel, separated facilities, which mitigate many of these issues, but create some of their own, like crossing joining streets.

**Many experienced bicyclists follow the more general rule that faster traffic passes on the left. What seems like weaving is actually predictable, safe behavior. When traffic is going faster, they pull to the right. When traffic is slower, they pull to the left. On the left, many of the problems described above don't arise. Drivers rarely open their doors when they are still in the lane. The left-hook is much less likely and easier to see coming. The cyclist is more visible to traffic. And, traffic is more visible to the cyclist. But, it isn't a strategy for the traffic-averse. We need to accommodate them, and parallel facilities fit the bill.

5 comments:

Steve R said...

I do pass stopped traffic on the right; I'm certainly confident enough to bike to the left of stopped traffic (and I'd rather be there, frankly), but getting there is often difficult. Even when I can plan ahead, cars slowing for traffic are often so densely packed by the time I match or exceed their speed that I don't have room to move left. Any suggestions on that maneuver?

My solution for riding between parked and stopped cars on the right is as you've suggested: slow and careful, scanning both parked and stopped cars for sudden movement. The key is to reduce speed to a comfortable jog--maybe 5-8 mph. At that speed, I can react to hazards, and I know I'll can be "breaking away" (movie reference for those over 40) when the traffic's moving again.

A flashing light also helps visibility. I don't have one (yet) but as soon as I do (soon) I'll be using it in daylight. I noticed one the other day on Beacon when I was driving: it was 50 yards back in my side-view. That immediately sold me on using a forward flasher in daylight.

dr2chase said...

I tend to pass to the right, not the left; my bike is large (cargo bike, daylight running lights, bottom bracket is a foot off the ground) and so I expect I am a bright distraction in people's rear-view mirrors, and also more likely to be visible to oncoming traffic that might be turning left. I realize that daytime running lights is one of those things that ticks people off because of the whole "gives the impression bikes aren't safe" thing, but I think it helps -- it helps for motorcycles and even cars, according to the studies I saw reported.

The "weave" maneuver, where you convert from right side to left side, or vice-versa, I do not like, because of the risk that cars might pick just the wrong time to move (I usually end up doing it when a car is too close to the curb, so there is no room, where the sidewalk option is illegal and/or unavailable). When I do it, I make a point of coming as close as possible to the rear bumper of the car ahead of me, to maximize the distance from the car behind that might lurch forward. This is not something I'd expect a new or uncertain cyclist to do well, among other things, it begins and ends with a quite-sharp turn (in particular, you do not want to pop out into the oncoming traffic)

One possibility, other than a daytime light, would be to install a good horn (Air Zound comes to mind) and to blow it whenever passing traffic on the right in the vicinity of a possible turn out. Horns are supposed to be safety devices, not get-out-of-my-way devices, so legally speaking this makes more sense than the way they are typically used on cars. HOWEVER, I had an Air Zound once, and accidentally used it on the MM trail instead of the ding-ding bell (behind a jogger), and I was so mortified that I took it off the bike.

Michael said...

As a motorcyclist I have sympathy for the situation. Sadly we are all less visible than we would like to be in traffic. I am a firm believer in reducing that disadvantage as much as possible. In my case I have a "rack" of bright lights on the front light bar which sometimes draws an angry light flash from oncoming traffic. I would try to emulate this system to the extent possible on a road bike to make the odds more favorable whichever side you choose to pass traffic.

Anonymous said...

There is always the bike priority lane. Hopefully a few brave souls will risk life and limb to make it better for the rest of us. Who is going to step up and take the challenge? The law be with you. http://www.boston.com/yourtown/news/brookline/2010/06/on_biking_a_ride_on_a_bicycle.html

cycler said...

I've made it my standard policy not to pass moving or "potentially" moving cars on either side. I mainly make an exception when there's a traffic jam caused by something I can easily slip around.
I used to "filter" but it's just easier and simpler and one less thing to worry about to stay in place in traffic. I suppose it would be faster to filer, but If I were worried about moving faster I wouldn't be riding a 40 lb lugged steel bike.
I've only had one accident in 4 years of daily commuting and it was a right hook where I rode up into someone's blind spot just as they turned right.
Cars can turn so quickly, and I just feel more comfortable holding the lane and moving when the cars move.
I guess the other side, is that I'm pretty aggressive about lane positioning, to keep drivers from passing me within the same lane. I feel like if I'm forcing to change lanes to pass me safely- in effect saying that this lane isn't wide enough for both of us to travel in it safely- its a bit rude and hypocritical to then pass them in the same lane when things slow down and it's convenient for me.
I know I'm an outlier on this, but since I started doing this this winter (when I HAD to ride way in the lane to avoid icy gutters) my commuting stress has gone WAY down.