Drivers often flout 30mph limits yet understand the reason for them

That finding from the Department of Transport ought not to be a surprise. A restriction of 30mph can seem severe, particularly if is on a wide, straight road

Yet it is one of the most important speed limits that is in force, because it typically applies in built up areas.

This means that there are countless risks, such as pedestrians suddenly emerging from behind a parked car or a car door suddenly being opened in the path of another vehicle.

Generally roads are safer to use the wider, less cluttered and more isolated they are, which typically means well away from urban areas (although country roads have their own perils).

The government findings on 30mph limits betray a wide degree of impatience with such a low limit, yet 30mph limits are observed more than they were 20 or 30 years ago.

An example is the Upper Newtownards Road past Stormont, which is heavily used and was previously treated by drivers as if it should be — and as if it was — a 40mph limit.

Now it the 30mph limits is widely observed, in part because it has a warning sign that flashes up when vehicles exceed 30, but also because such limits are better respected in general. Few drivers indeed would exceed 40mph in any 30 zone now, yet once such a clearly excessive speed was not uncommon on such a stretch of road.

Limits are not only better enforced, they are better understood, now that advertising, education and training have explained the reasoning for 30 limits.

There is also growing support for 20mph speed limits in residential streets, where driving at even 30 is too fast.

There is also perhaps a case for an 80mph limit on the safest roads, motorways, as compensation for restrictions drivers otherwise face but it would need strict enforcement.

Overall, greater caution on speed is a reason why many fewer people are dying in crashes than they did 20+ years ago.