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From: rs55611@ihuxk.UUCP (Robert E. Schleicher)
Newsgroups: net.auto
Subject: Re: Eliminate traffic congestion
Message-ID: <672@ihuxk.UUCP>
Date: Tue, 3-Jul-84 13:17:47 EDT
Article-I.D.: ihuxk.672
Posted: Tue Jul  3 13:17:47 1984
Date-Received: Wed, 4-Jul-84 04:34:41 EDT
References: <2349@hplabsb.UUCP> <3069@brl-tgr.ARPA>
Organization: AT&T Bell Labs, Naperville, IL
Lines: 29

The idea of using electronic position sensors to minimize car-to-car
distances (and thus get more cars on a crowded highway) would be fine
if the only variable in stopping time and distance was reaction time of the
driver.  The electronics would effectively eliminate the reaction time to
some very low number.  However, actual stopping distances of different
vehicles vary tremendously (fully-loaded semi vrs. a 2500 lb. sports car
with four-wheel disks nd fat tires, for example), so the electronics would
also have to somehow know how fast the car in front was capable of stopping,
if the car in front could stop quicker than you.  Another approach would be to have
all vehicles programmed to have a maximum braking power (or minimum stopping
distance equal to the worst vehicle on the road.  This makes no sense
whatsoever.

While electronics will undoubtedly make braking systems safer in the near
future, I think it will only be in the mode of a fail-safe device that
will prevent drivers who aren't paying attention from rear-ending the car
in front.  The other use of electronics in braking systems that has already
been developed (by Mercedes and others) is in anti-lock systems which
automatically prevent wheel lock-up during panic braking, regardless of 
road and weather conditions. These use rotation sensors on each wheel,
and limit additional brake fluid to any wheel that is rotating appreciably
slower than the other wheels.  This system was available on some higher
priced Mercedes as an option, and works very well.  You can slam on the
brakes in a turn on a snowy road, and the car will slow down as fast as 
possible without sliding.

Bob Schleicher
ihuxk!rs55611
AT&T Bell Laboratories