Help-what is stopping distance on gravel roads

[mdbarb]

Re: stopping distance on gravel roads

Thats a good point.
I got that number from the "NHTSA Light Vehicle Antilock Brake Systems Research Program Task 4: A Test Track Study of Light Vehicle ABS Performance Over a Broad Range of Surfaces and Maneuvers". which is locate on the National Highway Traffic Safety Administration's web site at page 50 of http://www-nrd.nhtsa.dot.gov/vrtc/ca/capubs/NHTSAabsT4FinalRpt.pdf
I understand it to be an overall percentage

 

[beenthere]

Re: stopping distance on gravel roads

Mdbarb
I wasn't questioning the percentage figure that you used. But it seems that percentage would only apply to the stopping distance (brakes applied) number you had for a given speed, NOT the combined stopping distance AND (plus) the reaction distance traveled before applying the brakes. Hope this makes sense, as the reaction time (distance traveled) is the same regardless of having ABS brakes on the car. Don't want you to get picked apart on something other than the figures you present.

 

[MikePA]

Re: stopping distance on gravel roads

I have read that increased stopping distances with ABS on gravel, as well as loose snow, is that the build up of gravel and snow in front of a locked tire assists in stopping. With ABS there is less of this build up.

 

[mdbarb]

Re: stopping distance on gravel roads

What you say is true. ABS has nothing to do with reaction time. It seems they just lumped it all into one total. So actually if the overall increased by 27.2 % but the reaction time was not affected, the the percentage of increase would actually be higher. ...I think... /w3tcompact/icons/hmm.gif

 

[beenthere]

Re: stopping distance on gravel roads

<font color=blue>So actually if the overall increased by 27.2 % but the reaction time was not affected, the the percentage of increase would actually be higher. ...I think... <font color=black>

What you conclude is true....IF the 27.2 % applies to the combined distance.

However, I can't imagine figuring it that way, so if I had to defend some numbers, I would pick the more conservative ones. They are long enough distances to get your point across, are they not? You can decide which will be easier to present and defend as the most realistic and that support your side of the debate the best.

 

[mdbarb]

Re: stopping distance on gravel roads

Sure - We could throw out the abs factor totally and he would still be driving too fast.
There are also so many other variable that would add time distance too. Perhaps his reaction time is slower, pehaps he doesn't even see the pedestrian to even begin reacting, what effect would a 1% slope have..etc. etc...