I NOTE that the authorities are to have a look at the effectiveness of speed limits in promoting better driving ("Drivers who speed set to be given lessons and not points", The Herald, January 1).

Until 1965, there were no speed limits on British roads outside built-up areas. A series of accidents in fog where excess speed was identified as a contributing factor brought about a trial speed limit. The arbitrary speed limit of 70mph was made permanent by Barbara Castle, the Transport Secretary, in 1967.

Speed limits may have the opposite effect than that of reducing road accidents. The 70mph limit suggests that on a motorway, if you are travelling at 70mph or less, you are driving legally and safely. While you are legal, whether you are safe is entirely dependent on the conditions. Driving at 70mph through thick fog is legal but dangerous. If you can’t see where you are going, slow down. Driving at 70mph in snow and ice is equally dangerous, but not illegal.

Since 1965 there have been major advances in vehicle technology including braking systems. There have been no such advances in the most important part of a vehicle in motion – the driver. In 2018, there are many more distractions such as mobile phones, audio systems and the like.

The authorities should consider whether speed is the cause of road accidents or the distracted brain behind the wheel.

John Black,

6 Woodhollow House, Helensburgh.