The Chainlink

After Dustin Valenta's awful dooring and hit-and-run last week, I've been thinking about how to minimize injury when one is doored. I was lucky enough to come away from a dooring this winter with minor injuries because I swerved left and THANK GAWD there was no car in the lane behind me, but I could've very easily been hit by a car in the travel lane and sustained a really serious injury.

So when you see the door open and you don't have time to stop: what's the best thing to do? Should you brake hard and hope that you don't skid into something that will kill you? Steer into the open door?

I haven't found any great physics/medicine papers on this yet, and would appreciate the input.

Tags: dooring, injury, prevention

Views: 706

Reply to This

Replies to This Discussion

Not sure you can make an action plan for such a thing.  I would imagine that instinct would decide.  Swerve?  Brake?  Take the hit?  It depends on what nanosecond you have when you see an open door.

I suppose, aim for the softest part, which would be the driver.

Since my dooring on Milwaukee in April of 2009 (from the passenger side of a car stopped in traffic), I have slowed my speed considerably when riding on Milwaukee Avenue. Additionally, I typically ride just to the left of the stripe delineating the bike lane. I make frequent shoulder checks so I have a pretty good mental image of what's coming up behind me in the lane of traffic, should I need to move further to the left unexpectedly. And there are times of the day/levels of traffic that I simply will not ride on Milwaukee Avenue. 

I haven't been doored, but I doubt that many people who get seriously injured in a dooring have time to really mitigate the impact.  That said, physics says:

The impulse force is related to the change in momentum (mass * velocity) / change in time (time at which the cyclist's velocity = 0 - time at which the cyclist gets doored).

Since your mass is constant in the timeframe of a dooring, that leaves us dealing with either (a) your velocity or (b) increasing the length of time between when you hit a door and when you come to rest.

But... you really can't control (b) either; dooring is so brutal because the time delta for a change in your momentum is very, very small.  The car is hugely massive relative to you: you hit it, and you stop.  Since the door and its hinges are effectively a lever with some flexibility, taking the hit on the outside of the door (closer to the street than the car) might increase the time delta, thereby reducing the impulse force -- but that also puts you closer to the street and traffic.

The only solution within your control to make dooring less awful is to slow down (and pay attention) when you're in a place where dooring is a possibility.  Oh - and wear a helmet, since your skull doesn't like being slowed down quickly any more than the rest of your body.

I agree with what Lowe said.

My personal opinion would be to take the hit into the door/(hopefully)exiting driver. I feel that you'll stand a much better chance of surviving a direct impact with an open car door than you would a glancing blow off the door and into traffic. Plus, as Lowe pointed out, the car door isn't the "car" and has a much lower mass than the car itself and the hinges on the door will act as springs, prolonging your delta t. Both these things will help to reduce the force of the impact.

That said, I understand that in most (all?) of these instances there will be no conscience thought processing, it's going to be all instinct. My first instinct in the past has been to swerve to the left, into traffic.

Some random side thoughts:

  • car doors could be engineered such that they'd easily fail (crumple/detach from the car/etc.) under a load equivalent to the magnitude and direction a cyclist places on the car during a dooring incident.
  • Would it make sense to perhaps swerve right into the side of the car if possible. This would help to slow you down before impacting the door (maybe?).

The best advice from above is to slow down where doors, poor maneuverability (i.e street), and traffic coexist.  Riding out of the door zone whenever possible should be a given, but it needs to be reminded. If a dooring occurs, it's a complex equation, and so will be your response depending on how you respond to danger in general.

In other words, as our famous man on the 100 bill said, "28.35 grams of prevention is worth 453.59 grams of cure";)



Chi L

But... you really can't control (b) either; dooring is so brutal because the time delta for a change in your momentum is very, very small.  The car is hugely massive relative to you: you hit it, and you stop.  Since the door and its hinges are effectively a lever with some flexibility, taking the hit on the outside of the door (closer to the street than the car) might increase the time delta, thereby reducing the impulse force -- but that also puts you closer to the street and traffic.

The only solution within your control to make dooring less awful is to slow down (and pay attention) when you're in a place where dooring is a possibility.  Oh - and wear a helmet, since your skull doesn't like being slowed down quickly any more than the rest of your body.


Good advice above.  Avoiding being doored is the #1 thing to do.  By that I mean preparation- awareness, your position in the lane, your rate of speed, your frickin' helmet. That being said, there may come a time when you simply know that you will be doored. In the nanonsecond referred to above the first question is whether to swerve.  If you can see what is behind you to your left you can make the move. If you do it blindly...you may become a ghost bike.  You may have to prepare to hit the door, dive into the car, vault over the door.  None are good options. Its also tough because its counter intuitive. The mind wants to avoid the obvious contact. The problem is the path of avoidance may be blindly into death rather than aware into  a broken arm. Ever since the dooring  on Wells St. last  year I have been asking myself if I will have the confidence to ride into the door and take the hit if I am unsure about the safety of a swerve.  I may not know until I am forced to make the choice.

Having been doored a few times over the years, I've found that there is no universal answer for all situations.  The closest I could come is this.

1.  If at all possible to ride completely out of the door zone, DO IT!

2.  If you're on a street like Lincoln where it's usually a choice between riding in the door zone vs. drivers breathing down your neck if you take the lane, take the lane when possible and GO SLOW when the door one is your only option. 


If you're going 10-12 mph vs. 15 or more, you'll have more reaction time to avoid a crash.   If you have a crash anyway, you're likely to suffer less damage. The slower your speed, the lower the force of impact = less trauma to your body.

3. Some factors will be beyond your control. The nature of the crash and extent of your injuries will vary quite a bit depending on whether the door opens in front of you or next to you, how high the door is relative to your riding position (low sports car may stop your bike but not you, while SUV may stop both), how fast you're going, whether there's a vehicle in the lane next to you when you get hit, etc.  In other words, your mileage may vary.

4.  Keep your eyes and ears open.  If you see a car parallel parking ahead or brake lights going off, you know that driver is likely to get out sometime soon.  If you're near a cab with a passenger, the passenger's movements may give you advance warning that he/she will exit soon.  When in doubt, slow down and/or stay further away from that vehicle.

I've been doored 3 times over the course of 20+ years and avoided hundreds more by looking, listening, braking and swerving.  Again, your mileage may vary.

In general I'll agree with what you and Lowe have said, but with one change. Instead of hitting the door head on, turn the wheel somewhat parallel with the door so that you have a glancing initial impact that leaves you sliding along the door toward the car interior. This increases the distance you travel while stopping, thereby decreasing the force required to stop. Also it will leave you coming to a stop away from traffic and impacting the relatively soft car interior/driver.

As for your idea about designing car doors to give way, it's not a complete impossibility and if it happens it will be because of Europe. European crash standards included sections for protecting pedestrians that have lead to things like collapsible hoods and bumpers designed to scope a person onto the hood rather than push them under the wheels.


Will G - 10mi said:

I agree with what Lowe said.

My personal opinion would be to take the hit into the door/(hopefully)exiting driver. I feel that you'll stand a much better chance of surviving a direct impact with an open car door than you would a glancing blow off the door and into traffic. Plus, as Lowe pointed out, the car door isn't the "car" and has a much lower mass than the car itself and the hinges on the door will act as springs, prolonging your delta t. Both these things will help to reduce the force of the impact.

That said, I understand that in most (all?) of these instances there will be no conscience thought processing, it's going to be all instinct. My first instinct in the past has been to swerve to the left, into traffic.

Some random side thoughts:

  • car doors could be engineered such that they'd easily fail (crumple/detach from the car/etc.) under a load equivalent to the magnitude and direction a cyclist places on the car during a dooring incident.
  • Would it make sense to perhaps swerve right into the side of the car if possible. This would help to slow you down before impacting the door (maybe?).

This discussion is reinforcing my initial thought, which was to brake hard and steer into the car. (Better the devil you know- stationary object- than the devil you don't- potentially lethal traffic in the travel lane.) Not having any physics or medical background I also felt like potentially hitting a substance with any "give" (ie the person who just opened their door) would be more forgiving to my own body than asphalt, but there seems to be a lack of case studies and research on this, based on my afternoon's googling. 

Here's hoping I don't have to put this into practice, but yes, if I can think through it before the situation occurs and train my brain to react without thinking in the moment, I feel that'll give me a better change of retaining my own structural integrity.

the interior of the car doors should have some reflective element (like the outline of the door).  i noticed how hard it was for me to see open car doors when it was raining at night.  it didn't tell help that my route was poorly lit.  i've hit the driver's side of a car at low speed.  the bike stopped upon hitting the door, but i got pushed forward.  i guess try to pivot so that your shoulder impacts the car (as opposed to your face).  most crash scene photos, the person's bike looks like it skidded towards traffic.  i'm not sure what if anything that is telling of the physics of the collision.  

This.
Much better to avoid a dooring in the first place than to deal it one.

Kevin C 4.1 mi said:

Since my dooring on Milwaukee in April of 2009 (from the passenger side of a car stopped in traffic), I have slowed my speed considerably when riding on Milwaukee Avenue. Additionally, I typically ride just to the left of the stripe delineating the bike lane. I make frequent shoulder checks so I have a pretty good mental image of what's coming up behind me in the lane of traffic, should I need to move further to the left unexpectedly. And there are times of the day/levels of traffic that I simply will not ride on Milwaukee Avenue. 

I agree. As I've said elsewhere, my target will be the arm that opened that door, and if I break it, then I've shared the pain and dissipated a fair bit of the force with that impact. I'd rather be splayed across the hood of the offender's stationary vehicle than run over by an oncoming vehicle.

Now, if we'd all switch to driving Lamborghinis with scissor doors, the world would be a better place.


D Horst said:

This discussion is reinforcing my initial thought, which was to brake hard and steer into the car. (Better the devil you know- stationary object- than the devil you don't- potentially lethal traffic in the travel lane.) Not having any physics or medical background I also felt like potentially hitting a substance with any "give" (ie the person who just opened their door) would be more forgiving to my own body than asphalt, but there seems to be a lack of case studies and research on this, based on my afternoon's googling. 

Here's hoping I don't have to put this into practice, but yes, if I can think through it before the situation occurs and train my brain to react without thinking in the moment, I feel that'll give me a better change of retaining my own structural integrity.

Reply to Discussion

RSS

© 2008-2013   The Chainlink Community, L.L.C. Julie Hochstadter, Director   Powered by

Disclaimer  |  Report an Issue  |  Terms of Service