Safety Corner logo



Opening Doors

Safety Corner logoby Tad Staley


A car door opened suddenly in front of a bicyclist is one of the great and unanticipated hazards of bicycling on streets shared with automobiles.

“Dooring” crashes can also be some of the most serious, especially when the opening door causes the bicyclist to fall into passing traffic. Even the slightest contact between a car door and the end of a handlebar can result in a spill. And dooring collisions don’t only occur on the driver’s side of the car - passengers exiting a car can be trouble for bicyclists passing a parked car on the right.

Dooring incidents are far from uncommon. Dooring crashes constitute between 5% and 16% of all injury-producing incidents, according to CRW Safety Committee member John S. Allen who cites various sources in his article about car-door collisions, on-street parking and bike lanes. (

How to Avoid Being Doored
The first step in avoiding getting doored is to recognize that it can happen unexpectedly. You can try to look inside each parked car before you pass it and respond accordingly, but in his book Effective Cycling, John Forester describes the limitations of this approach. “At 15 mph it takes more than two car lengths to recognize a danger and stop, and you can’t see the danger two car lengths ahead.” With increased use of tinted windows in automobiles, it has become more difficult to look inside parked cars.

The Door Zone is an imaginary 4-foot buffer along the side of a parked car where an opening door can hit and seriously injure a bicyclist. One simple test of whether you’re in the Door Zone is this: if you could reach out and touch a parked car as you pass it, you’re vulnerable to opening doors.

Even in cases where there is a bike lane alongside a row of parked cars, it doesn’t mean it’s safe from doors. When riding in a bike lane, ride on the left side of the lane - again, at least 4 feet from parked cars. The additional space helps you avoid other hazards too, such as pedestrians who step out from between cars, or a car that encroaches onto the street from a driveway to allow the driver to scan for cross traffic.

Between a Parked Car and a Hard Place
Creating this buffer between you and parked cars can put you into an active traffic lane. The web site suggests that in this case, a bicyclist should assert his or her legal right as a vehicle driver: “Ride far enough to the left that you won’t run into any door that’s opened unexpectedly. You may be wary about riding so far into the lane that cars can’t pass you easily, but you’re more likely to get doored by a parked car if you ride too close to it than you are to get hit from behind by a car which can clearly see you.”

John Forester agrees: “If someone opens a door close ahead of you, you have only one choice: dodge out into the traffic lane. It is much safer to ride there consistently in the first place.”

If possible, keep track of other vehicles behind you with a small mirror mounted to your helmet or handlebars, and by scanning frequently. This will help you interact better with overtaking traffic.

Official Solutions
In many states, including Massachusetts, laws exist to help protect bicyclists from being doored. Since passage of the Massachusetts Bicyclist Safety Law in January, people in cars can be ticketed and fined up to $100 for opening doors into the path of any other traffic, including bicycles and pedestrians. For the full text of the new law, see

Don’t count on the new law to change motorists’ behavior, however. Few people know of the new law and even those that have read it may not be thinking about the consequences when opening their car doors.
Several cities have taken a more practical approach to guiding bicyclists past parked cars. On certain streets in Cambridge and East Boston, for example, you can find chevrons painted 11 feet from the curb and 4 feet from parked vehicles. These shared lane markings, or “sharrows” (share + arrows) are used on roads where there is not sufficient width to stripe a bike lane as a way to indicate where bicyclists can ride safely out of the door zone.

In Closing
Don’t count on being able to see, anticipate or respond to a door suddenly opened in your path. The safest approach is to maintain a healthy distance from parked cars - on the left edge of the door zone - even if it means edging out into an active travel lane. Maintaining that buffer could be a life-saving decision.

Please send corrections, additions, comments and praise to Safety Web Admin

© 1997- CRW, Inc. All rights reserved. Revised: