How wide is a car door?
 

Therefore, how wide is the door zone? I could take some measurements myself, but of course they will vary somewhat by model. I'm figuring probably 3-4 feet, but I wonder if there are any official numbers given in any street design guide somewhere. Anyone know?

Check John Allen's work first:

http://www.bikexprt.com/bikepol/faci.../doorwidth.htm

I have other references, if that doesn't get you going in the right direction...

I've heard 4-5 feet for the door zone - this is from Hurst's book.

Don't car companies publish specs for these sorts of things? We could just find the largest one available (Bet you it's a cadillac or lincoln or buick) and make the door space 2 more feet beyond that.

Thanks for the replies. John Allen's page gives total vehicle widths for sampled vehicles ranging from 103 to 123 inches (8'7" to 10'4"), including 6" away from the curb. But he doesn't break it down by just door width and vehicle width with door closed, so I don't have just the door numbers. Nonetheless, taking into account width of handlebars, he claims that gives only 10-15" of non-door zone tire track space in the left part of a 5' bike lane next to a 7' parking lane, configurations supported by both AASHTO and the Chicago manual. (I'm not sure what math he's using, I get between 8" and 2.5'.)

FWHA states 2.4m (7.8') to be a standard car width, so add Hurst's 4', and you have close to 12', which leaves nothing outside the door zone in a 5' bike lane next to a 7' parking lane!

I think that's pretty much accurate, in the real world. IOW, almost no North American bike lanes striped next to parked cars are safe to cycle in.

And in the real world they park more than 6" away from the curb...

Aaron:)

I don't have the book in front of me, but I could have sworn he said 4 feet, or 3-4 feet. I remember thinking it was on the low side.

See the article "Bicycling and on-street parallel parking" at http://www.humantransport.org/bicycl.../door_zone.pdf

Could be. 3' is probably too low, you'd potentially hit the door, but then again, at 3', you would probably have enough time to react to the door opening if you were vigilent. Closer than that, probably not.

:eek:

Common misconception alert!

Time to react? Maybe... but "react" in what manner? Time enough to swerve left to avoid hitting the door, right into the path of the bus that is about to pass you at a speed differential of 10 mph?

Here's the worst part: your speed doesn't matter. You can be crawling at 3 mph, and if a door suddenly swings out and hits you in the handlebars or leg or something, it could instantly cause you to fall into traffic.

The only way to deal with dooring is to stay COMPLETELY out of the door zone, period. No exceptions. That should be your habit.

Absolutely right.

So if you want a completely safe 5' bike lane, next to a 7' parking lane, what is really needed is 4' of crosshatching between the bike and parking lane to indicate no one should be there (except on your way to or from your parking space). Is this ever done?

That would mean Chicago's minimum 44' road width (10' travel lane, 5' bike lane, 7' parking lane, on each side) turns into a requirement for 52'.

Reactions are always a "for better or for worse" deal. I'll venture that a bike messenger with several years of experience has his lines drawn more finely than you do.

And don't worry. I don't make it a habit to ride in door zones. I stand by my 4-5' rule for cyclists with my level of experience. Messengers... they have their own rules as they are more informed of traffic patterns and their own limitations than other cyclists generally.

Yes; one must wonder whether some of these minimum "standards" are really motivated by safety, or by a desire to shoe-horn bicycle-specific markings into the road for the sake of having bicycle-specific markings.

i don't measure -- by eyeball, it's pretty simple; take at least 1/3 of the lane when approaching parked cars, and let the whiners honk. so far, only one honker in the last 14 months.

The lane width taken by an opening door is less than the door width, because the doors do not open to 90 degrees and the hinge is usually aft of the front edge of the door.

It depends on the car.

Great post

Huh, reaction time for you shouldn't matter. You're the one that says you can avoid a collision from a car that leaves the stop line on a narrow residential street as you enter the intersection... while you are moving at 20MPH.

With reactions like that, you should always be able to ride in the door zone. I don't get it. :rolleyes:

I don't know the dimensions, but I ride on a road with a painted bike lane, right next to a parking lane once in a while in Providence. Typically when someone opens the door the whole lane is taken.

Gene,

I can't make sense out of this. Are you just looking for an excuse to harass me about something I wrote (and you apparently misinterpreted) in some other thread (which would be in violation of the harrassment and disruption guidelines - which luckily for you are not enforced) , or do you have a point relevant to this discussion? Because if it's the latter, I don't see it.

No matter how fast someone's reaction time is, the only way to avoid a suddenly opening door is to swerve left, possibly into traffic.

Having a fast reaction time is irrelevant. In fact, a slow reaction time might pay off here, because smashing into a door is probably better than swerving in front of a car, truck or bus....

I suppose those messengers with unbelievably fast reaction times and incredible bike handling skills could slide the bike under the door as they jump over the door, and rejoin on the other side.

Harrass you... no way... just trying to point out the realities of the road. Personally I stay well clear of door zones too. But you have told me that your superior training would keep you out of some situations that others have been injured in.

I thought perhaps you could avoid opening doors at 3MPH too.

Guess I am wrong.

So cars leaving the driveways or limit lines as you enter the intersection might be difficult to dodge perhaps?

No way. 3 MPH is 4.4 feet/second, or about 2 feet in half a second.

If a door suddenly opens just as you're passing it, it can easily push you falling right into traffic.

I think a common misconception about dooring is that the main thing to avoid is slamming into the door. I disagree. To me, that seems of secondary importance to avoiding swerving into, or being pushed into, traffic.

Of course they might be difficult, even impossible, to dodge if you ride too close to them. That's why you avoid the "strike zone" in front of them for the same reason that you avoid the "door zone" to the side of parked cars.

It's also why you avoid the "strike zone" behind cars parked at an angle (think north-side/westbound-side of Eastgate Mall between Regents and Genessee), or downtown Encinitas.