As can be seen by all the following comments, this is a
Weather/road conditions, type and condition of vehicle,
If nothing else, these do highlight the amount of time and
An even easier way to convert speeds into feet per
The charts are featured at the foot of this
However, when the driver is not on the “alert” mode, the reaction time
To the stopping distance, a big contributive factor, after the Human
A Cf between the dry asphalt and perfect tires is significantly
Thus the ideal coefficient of friction (0.8) would be between a perfect
Although the same road conditions, the Fc decreases to 0.7/0.6/0.5 if
As for the stopping distance, in my opinion, the easiest way to
Multiply the first digit of the current speed with itself. Such as:
Although the information given below
Your advice on
Those of us who have the
The 1.5 seconds quote is an
Applying 1.5 seconds to your
I just want to point something out that seems to cause a lot
This bit of information from John Ruller is informative but
Let’s try to clear this up. The 1.5 second figure that John
If we look at the Highway Code, what we see labelled as
IF the driver is aware of the hazard ahead and knows
However, to react promptly, the driver has to be already
However, in real driving, the driver needs to SEE
This is the true “Thinking” distance and it has to
If the driver isn’t aware of the hazard, either through lack
So if the driver’s not on the ball and it takes 2 seconds
So to calculate stopping distances from 60mph:
Overall Distance 416ft
OK, that is pretty much worst case scenario for the inattentive
Just as well brakes have got better since those figures were
With thanks to Mr. Alex Beet
Instead of having to learn all the data
x? ? 20 + x = Overall stopping distance in
x = speed
For example: If you are travelling
Braking distances for cars. Why
Overall stopping distances (that
Somewhat easier to work out than square
Peter Maddison has
I have an easier solution to Overall Stopping
Kevin Balding – I
1. take the first number of the speed i.e. 5 for 50
2. divide by two and add one to the answer (This will give
3. Multiply the answer by the speed = overall stopping
4 thinking distance in feet is the same as the speed
5. subtract speed from stopping distance to give breaking
all I have to remember is divide by two and add one.
e.g. at a speed of 50
5/2 = 2.5+1 =3.5 x 50 = 175ft overall stopping distance
take of the thinking distance (speed) 175 – 50 = 125
When trying to visualise a
Another way of judging distances has been sent in by
“Pick a fixture on the side of the road (such as a bridge or
Along similar lines
“One thing I remember from a long
I must admit I have heard this before but
I read your article on stopping distances and the laudable contributions by many experts, one or two I recognise having been in the driver training industry for a number of years.
The calculations and debate are great, very informative however I refer to your DOS to Windows conversion and the principles of this web site, make it all understandable for novices.
I have yet to meet anyone who has remembered the stopping distances they so studiously memorised when passing their test far less the Speed = Distance/Time calculation a week after passing their driving test.
The fact is, it’s meaningless, just figures and as most of us learn by visualisation and experience it’s no wonder we forget it.
I’ll also dispel one myth here, the ‘two second rule is nonsense’, although I haven’t worked it out, evidently its incorrect for all but one stopping distance in the Highway Code but what’s more important is that if drivers are continually spotting stationary objects to check their distance from the car in front, how much concentration are they devoting to actually driving?
A cars stopping distance is the lowest common safety denominator. Ask any ‘advanced’ (I hate that elitist term) driver what the most important safety skill drivers should develop and they will almost all say “observations” (every single one I have asked) then ask them what it is in thick fog when observations are virtually useless and they will almost always say “stopping distance”, the last and default safety position.
Unfortunately we confuse our learners by continually throwing figures at the problem when, by our own admission, there is still debate amongst the experts as to what should be considered the finite calculation.
The vast majority of cars on the road are driven by reasonably healthy adults with good eyesight and reasonable reactions. The highway code advises us to beware of other vulnerable road users so elderly drivers, people on their mobile phones, with kids in the car etc. should all be given more time and space by us.
For the rest of us, the visualisation of, say, 23 metres ought to be automatic, many guys will respond to “roughly a quarter of the length of a football/rugby pitch” (and yes I know they vary in length but it’s better than nothing). From that default the calculation becomes more manageable and I was taught that we should be looking at roughly 1 Yard for every mile per hour travelled. Times have changed and the Yard is now a metre, even more useful as at roughly 39 inches it’s about 7%(?) more which gives us a nice little advantage but although it becomes less accurate above 50mph or so its memorable and more important, recognisable especially when drivers can visualise 23M then mentally multiply up.
One of you’re contributors mentioned the problem of people overtaking and pulling into the gap they had left. I would remind him/her that the distance you leave between yourself and the car in front is also the space you need to leave for overtaking vehicles. The reality is, no matter what gap you leave, if
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