During my daily commute, I am too frequently put in danger by drivers who don't know the 2 Second Rule for following another vehicle. Between nervous glances in my rearview mirror, I often think about different methods that could be used to measure the time interval between my car and the one behind me. The device could detect if their is not sufficient stopping distance between my rear bumper and the car behind me.

I have always thought of this in the context of alerting me of a problem, but it has occurred to me that for this device to be useful, it has to impact the tailgaters driving, not mine.

So here's a discussion question: If you could detect a tailgater, how do you use that signal to get someone off your bumper?

 

Since this is rather simple technology, many high end vehicles have sensors to adjust the cruise control setting based upon the distance to a vehicle in front of the car, using the same technolgy, just have the device flash your brake lights on.

Oh, the following rule is 3 to 4 seconds, at a distance of 2 seconds, many state patrolman will write you a ticket for following to close. Simple math also will tell you that at 60mph, 2 seconds is not enough distance - ~88ft/sec = 176ft, put in reaction time, you will probably exceed 220ft easy and many cars can barely stop in that distance.(at 30 mph, this is ~44ft/sec, which is 88ft, + reaction time, so you could be in the 132ft or more range.) I am allowing for only 0.5 seconds of reaction time which is less than average, based upon NTSA studies. Braking reaction times and distance studies are done on closed courses, with profesional drivers, under ideal road conditions, with properly inflated tires, and are usually based on a panic stop conditon, since this does not happen in day to day driving and we are all not professional drivers, reaction times are higher, distances are greater and drivers are not paying attention enough and they are not performing panic stops in traffic, road conditions are not ideal, tires are worn, improperly inflated and that guy behind you is digging for a CD or tape.

Sure I can get my Suburaban to stop in a very, very short distance, but I am not willing to prove that in traffic, besides its hard on the tires and the brakes.

I have taught my teenagers to follow at 4 to 5 seconds. Driving is all about physics, time, distance and awareness. If the guy behind you is not aware, well, he may be in for a rather big surprise one day.

When in traffic if someone tailgates my Suburban, I just tap the brakes a couple of times, they always backoff - no one wants to risk hitting anything from behind, especially something that big.

So, using the sensor to determine when a vehicle is closer than 3 seconds and having the brake lights come on will usually work, if not, just just slow down aburtly, if they hit you from behind it is their fault and they will also get the ticket for following to close.

Unfortunately, there are lots of bonehead drives out there, changing their habits is hard to do, I just pay attention and make sure they don't hit me. As my dad once said, the first two rules of driving are, don't hit anything and don't let anything hit you, this has served me well in over 30 years of driving. Since I don't hit things, I am more worried about the other things hitting me.

MJH

 

Using it to deploy a TOW missile should work. Or even a paint sprayer.

Regards

cww

 

Thanks for sharing the 4 to 5 second rule and for teaching it to your teens.

I will surely take this advice to heart. Afterall, a man who can teach a teenager ANYTHING someone worthy of great respect in my book.

Brian

 

WD40 sure blurs up a window enough to ruin someones tailgating confidence.

 

Brian,

Thanks! And for the other wonderful responses, the idea of launching a TOW missle, ejecting WD40, really made me laugh. I also though it would be great to just send out a signal over the FM bands and tell them to BACK OFF! Or maybe, a small well focused EMP to disable their car for a couple of hours!

MJH

 

What about a ninja-like spike dispenser?

No seriously, a lighted indicator in the back of the car being turned on and signaling Back Off or whatever?

 

you could light your tail lamps as if you were on brakes so that the car from behind should be afraid to get close to you...

even more you could have a led message panel to write "back off".

 

Flashing the brake lights sounds okay, but only if you are careful. It should probably only work if the vehicle behind you "approached" too close. IOW you measured the vehicle behind you at good distance, followed sometime later by the same vehicle being too close.

Imagine if you just did a lane change and the car in front of you hit its brakes? That's what would happen if it was just triggered by instantaneous distance measurement. Someone changing lane behind you would be quite surprised.

Very dangerous.

Rufus

 

A few months ago, I was on my way home from work, and I was following a Chevy truck. It was one of the smaller models from the mid 90s. We were going down an incline, and I got a little too close to his bumper, and when I did, suddenly all of the lights (brake lights, reverse lights, dome light, signal lights) all started flashing wildly in a sort of pattern. It scared the crap out of me, and of course I slowed down. Didn't dare get close to him again. I guess it served it's purpose, but I wonder if he had some kind of sensor kit installed on his car? I'd love to find one of those for my car.

 

Of course, that could have been manually operated as well. He may have just need to press the "Light Show" button on his dash.

But it still required some kind of controller inline with the light controls...