Stopping distances in the UK Highway Code should be re-evaluated as drivers’ thinking time has been underestimated, according to figures obtained by Brake, the road safety charity.

Brake asked the Transport Research Laboratory (TRL) to provide evidence on the time taken by car drivers to perceive, recognise and react to emergency situations. TRL referred to academic literature and concluded that the average thinking time is 1.5 seconds, more than double the 0.67 seconds set out in the Highway Code (see table).

This means that average total stopping distance − including thinking and braking distance − is an extra 2.75 car lengths (11 metres) at 30mph and an extra 3.75 car lengths (15 metres) at 40mph compared with the distances used in the Code. This difference rises to an additional 6.25 car lengths (25 metres) at 70mph.

Overall average stopping distances

Speed 20mph 30 mph 40 mph 50 mph 60 mph 70 mph
Brake/TRL study 19m 34m 51m 71m 95m 121m
UK Highway Code 12m 23m 36m 53m 73m 96m
Difference 7m 11m 15m 18m 22m 25m

Average car length = 4m

“These figures suggest stopping distances taught to new drivers in the Highway Code fall woefully short. Even though car braking technology has improved in recent years, the majority of the overall stopping distance at most speeds is actually made up of the time taken to perceive the hazard and react,” said Jason Wakeford, spokesman for Brake.

“The research shows that average thinking time is more than double that set out in the Highway Code. A true understanding of how long it takes to stop a car in an emergency is one of the most important lessons for new drivers. Understanding true average thinking time reminds all drivers how far their car will travel before they begin to brake − as well as highlighting how any distraction in the car which extends this time, like using a mobile phone, could prove fatal.

“Brake is calling on the Government to increase the stopping distances in the Highway Code as a matter of urgency,” Wakeford said.