An article by Eddie Wren
(Amended, August 2022)
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 crucial 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 (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 but instead to illustrate the extra dangers faced by, and caused by, those people who exceed the usual highway limits.