From: bqueiser@magnus.acs.ohio-state.edu (Brian J Queiser)
Subject: Doors locked while driving, good or bad? [was: Common Myths]
Organization: The Ohio State University
Date: Mon, 28 Dec 1992 17:11:39 GMT

oyalcin@IASTATE.EDU (Onur Yalcin) writes:

>>>One most common that I know is the belief that the doors should be locked
>>>during travel. This is as much wrong a belief as it is widespread.
>>>Actually, the doors are recommended to be *unlocked* during travel, so that
>>>...
>>>Some cars actually have a mechanism that pops the door locks open during a
>>>crash.

>> I think this information is entirely incorrect (but, hey, I've been wrong
>> before).
>>
>> Reason why is this:
>>
>> Car doors *should* be locked during travel for safety reasons.  First safety
>> reason is: carjacking, mugging, etc.  Second reason is:  door locks help
   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

>This reason is irrelevant with this discussion. The safety that is mentioned
>here is not related with that safety tried to be developed by the car
>manufacturers. It is just common sense to lock your door in an area where you
>don't feel comfortable, just like locking your house door at nights. This is
>not related with "driving safety".


Okay, okay, okay.  I was just trying to broaden the scope of the issue;
there are many facets to this discussion.


>> prevent door from opening during an accident.  Onur has it backwords; some
   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

>Eh, no... This is the "common myth" I was criticizing. Locking the car doors
>only prevents them to be opened by hand, from the outside door handle. Except
>that, locked and unlocked doors would react the same way to physical forces.
>Locking the door does NOT reinforce the grip of the door locks; it just
>disengages the exterior door handles.


I know what you were saying, I was just offering the opposing argument.
I am not certain, however, that door locks operate exactly as you mention
for all cars.  Locks can simply "bolt" the door mechanism, preventing it
from being operated at all, much like a padlock on a gate.


>> manufacturers put automatic *locking* mechanisms into doors, so that they
>> *lock* during a crash.  In fact, some newer cars have a "feature" that

>I have never heard of this feature before. But given what I wrote above, this
>is probably meant for cases that you put forward above (carjacking etc...).


This "feature" is becoming more common in newer cars, mostly GM; refer to
the Acheiva example below.  Does anyone know of others...?


>> automatically locks the doors when the car is put into gear.  (I call it
>> a "feature" because in some cases it is annoying, like in the Acheiva,
>> where the doors won't unlock and open when the handle is pulled, forcing
>> you to contort your hand to reach for the lock button that is placed in

>All the cars that I have driven, with only the exception of a friend's 84 Olds
>Caprice Classic (the only american I have driven so far) would let you open
>the door as soon as you pull the interior door handles regardless whether they
>are locked or not. What kind of a safety feature is this, if it makes you lose
>time to evacuate the car?


I think all Fords unlock when the interior door handle is pulled.  GM, for
the most part, does not have this type of handle/lock mechanism.  I don't
know about Chrysler, but I think they're much like GM when it comes to this.
Hey, I agree that one may lose time while trying to evacuate their car if
they've got to hurriedly find the locks.


>> an awkward position on the door.)  Third safety reason:  child locks in
>> back keep little hands from opening doors.

>Child locks act the way normal locks do. Except that child locks prevent the
>door to be opened from the *inside* door handle. Much like the normal door
>locks, they have no effect on the door's opening during the accident.
>Furthermore, they won't help you in cases of carjacking, too. Don't you agree
>that this is not really relevant?


I know how child locks work.  My point was that if doors are locked manually
or automatically when the car is put into gear, then the children in the
back are subsequently automatically kept from opening the door accidentally
(or purposefully) if the child locks are engaged.  I think this is entirely
relevant to the safety issue of driving with your doors locked.  Does anyone
with kids agree?


>> While I agree that it appears to be rather unsafe to be unconscious
>> and locked in your car, it is actually the lesser of two evils (vs.
>> getting thrown out; studies show that driver/passenger(s) are safer
>> in their car during an accident).  The window can be broken by rescue
   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

>I strongly agree with this. But, again, car locks do not improve this chance.


Those that bolt the lock/latch mechanism would.


>> crews or whoever else comes to the assistance of the car's occupants.
>> The glass is tempered so that it shatters into very small, relatively
>> harmless pieces (they look a lot like teeny, tiny cubes).
>>
>> Also, Mercedes and Volvo (and perhaps some others) beef up their door
>> handles so that they can be grabbed and pulled on rather forcefully,
>> or so a crow bar can be slipped through, etc.

>My Renault 21, All Opels starting from Kadet (same design as pontiac Le Mans i
>the US) - that is the Vectra, Omega and the Senator; And Audis equipped with a
>pro-con-ten safety package (the one alternative to air bags - where the steer-
>ing wheel is retrieved backwards, away from the driver) pop the door locks
>open in case of an accident. This is sensed by essentially the same mechanism
>which activates the air bag (i.e. as soon as a deflection is sensed in some
>particular part in [or under] the hood).
>
>Given the door locking feature that Brian mentioned, I should admit that this
>matter is not as straight as I see it. Maybe the locking mechanism on those
>cars is different - but I doubt so.


Okay.  So what we have here is this:

If, and that's a big IF, door locks bolt the latch mechanism, then the door
is more likely to stay shut in an accident.  I think we all agree that this
is good.  However, a locked door is a hinderance to someone trying to get
out or someone trying to get in (to save the car's occupants).  So what we
need is this:  a door locking system that automatically locks the doors
either when the car is put into gear or immediately upon impact during a
crash, and then automatically unlocks them after the accident (say, when
all motion has stopped).  Is this available on any car?

Regards,

Brian

bqueiser@magnus.acs.ohio-state.edu
------------------------------------------------------------------------
I am the engineer, I can choose K.
------------------------------------------------------------------------
Department of Engineering Mechanics
Ohio State University
Columbus, OH