Help-what is stopping distance on gravel roads

[beenthere]

Egon, I too like that feeling on a gravel road. Never felt 'out of control' although I probably was most of the time. One could do a do-nut real easy in the middle of the road with just the right braking and accelerator in combination. Now I just watch them do that on NASCAR races.
I once rode double with a neighbor kid driving his new English cycle in the middle 50's, when he put the speedometer up to 100 mph on a gravel road. At the time it was fun, and never 'felt' out of control. I think we were just off the gravel and not really in contact with it. Survived, but not something I wanted to repeat. He claimed he could go over 120 mph, and it looked like it sometimes when he went by on our gravel road.

 

[mdbarb]

Re: stopping distance on gravel roads

On a different, well read thread regarding my neighbor and an easement. I have a temporary restraining order slowing him down to 7 mph at the blind corners in my backyard. Tuesday we go back to court to discuss this and I would like to have some "facts" to show. He seems to feel that 20 or 25 mph is fine where one can see only about 40 feet ahead. I have found charts that show it would take about 65 feet to stop at that speed on an asphalt road. Gravel would obviously be even longer. But I need some "Facts" for de judge.

 

[Turfman]

Re: stopping distance on gravel roads

Catch me privately and I'll e-mail you the information from the KING of speed and accident information, Northwestern University Traffic Institute.

 

[ByuBill]

While considering all of the variables mentioned above. You also have to take into account if the vehicle has ABS or not. The stopping distance on a gravel road for a vechile equipped with ABS can be from 20-60% further, depending on the ABS system and the condition of the road. Although, with ABS, you have the option of being able to steer.

 

[patrickg]

Re: stopping distance on gravel roads

Don't forget to factor in reaction time. Distance to stop doesn't begin until after the brakes are applied. Reaction time for your neighbor's age group and general health would be fair to use (too bad you can't use his mental health).

Patrick

 

[mdbarb]

This is good.
What is the source for this formula - They could say I'm just making this up.
Just to make sure I've got it - 25 mph on a level gravel road:
25 x 25 / (30 x .4)=52.08 ft.
Now I understand ABS brakes actually lengthen the stoppping distance and this does not take into consideration the reaction time before braking

 

[Green_in_MI]

A search for stopping distance info will find lots of hits for paved roads. I suspect the variables for gravel road are so many that all bets are off when not on pavement. Just guessing, I would use a coefficient of friction about half that of pavement.
Now if you are asking for stopping sight distance that is another matter.

 

[PaulInMi]

If its not too late, you can email or call me directly and I can give you some information that we use in accident reconstruction/w3tcompact/icons/smile.gif.

Paul
pcmhart@chartermi.net
810-750-6148

 

[mdbarb]

Re: stopping distance on gravel roads

This is the little chart I came up with combining everyone's input so far

 

[beenthere]

Re: stopping distance on gravel roads

<font color=blue>
Speed............gravel..........reaction.........+ 27.2 % ABS.............Total

25.................52.083............55.............107 (0.272) = 29.13........136.21...your numbers
<font color=black>
25.................52..................55................52 (0.272) = 14...........121.......my numbers

Is the increase in "Stopping due to ABS brakes" a percentage of the stopping distance on gravel? rather than a percentage increase of the stopping distance on gravel and the reaction distance?