Stopping Distances

 

and

 

Following Distances

 

 

 

All contents copyright , Drive and Stay Alive, Inc., 2003, unless specified otherwise. All rights reserved.

 

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Stopping Distances

An article by Eddie Wren

 

(Amended, August 2004)

 

With the advent of better brakes, vehicle stopping distances have reduced somewhat over the years but it has to be remembered that, no matter how good the brakes and tires, the laws of physics don't change.

 

The most important point for any driver to remember is that if you double your speed -- say from 30mph to 60mph -- your braking distance does not become twice as long, it becomes four times as far.

 

Because there are differences between various vehicles, the following tables are for guidance only. The biggest factor in stopping distances is the speed at which a driver reacts to seeing the hazard in question. Under ordinary driving conditions, very few drivers indeed can get onto the brakes within half a second, and two-thirds of a second to a full second is more typical.2

 

Most frighteningly, Australian research has shown that the very people we expect to have the fastest reactions -- young drivers -- are particularly prone to effectively 'freeze up' with fear, at the sight of an unexpected hazard ahead, and their reaction time can therefore exceed two seconds.

 

Lastly, don't forget that when you read the 60-0mph figures in literature for new cars, the automaker is giving you only the braking distance, not the overall stopping distance.

 

 

Stopping Distances for Dry Pavement/Road 1

 

Speed

Thinking

Distance 2

Braking

Distance

Overall

Stopping Distance

Comparisons

20 mph

20 feet

  20 feet

  40 feet

 

30 mph

30 feet

  45 feet

  75 feet

Full  length of  tractor/semi-trailer or articulated wagon

40 mph

40 feet

  80 feet

120 feet

 

50 mph

50 feet

125 feet

175 feet

 

60 mph

60 feet

180 feet

240 feet

 

70 mph 70 feet

245 feet

315 feet

(USA = "Touchdown !")

80 mph 80 feet

320 feet

400 feet

About six semi-trailer or articulated wagon lengths 3

(Copyright , Eddie Wren, and Drive and Stay Alive, Inc., 2003 onwards)

 

 

Stopping Distances for Wet Pavement/Road 1

 

Speed

Thinking

Distance 2

Possible Braking

Distance

Overall Stopping Distance Can Be:

Comparisons

20 mph

20 feet

  40 feet

  60 feet

 

30 mph

30 feet

  90 feet

120 feet

 

40 mph

40 feet

160 feet

200 feet

 

50 mph

50 feet

250 feet

300 feet

(USA = Touchdown !)

60 mph

60 feet

360 feet

420 feet

 

70 mph 70 feet

490 feet

560 feet

 

80 mph 80 feet

640 feet

720 feet

Almost two and a half American Football fields 3

(Copyright , Eddie Wren, and Drive and Stay Alive, Inc., 2003 onwards)

 

Remember - 1: When the road is icy or covered with compacted snow, or diesel fuel has been spilled (which is a particular risk near certain gas stations) the 'braking distance' for your vehicle can be as much as ten times further than for dry roads/pavement.

 

Remember - 2: ...............Any fool can drive fast enough to be dangerous!

 

Notes

1  For non-US readers, 'pavement' is the American word for the road surface. We are not referring to the British meaning of the word, which is the same as the American 'sidewalk'.

2  The 'thinking distances' shown allow for two-thirds of a second reaction time. This varies from one driver to another and for individuals who are ill, tired or simply not concentrating, it can be much longer.

3  The 80mph examples are not here to condone breaking any speed limits, rather to illustrate the extra dangers faced by, and caused by, those people who exceed the usual highway limits. 

 

Click here to read about Safe Following Distances

 

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This page last updated on 11 Aug., 2004