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.