Speed limits hard to justify if not enforced
When the 20mph speed limit was introduced in inner Belfast at the end of January this year, Transport Northern Ireland said its primary aim was to reduce the number and severity of collisions on the city's streets.
It is an obvious and well-known fact that the faster vehicles go, the greater the risk of death or serious injury in any crash.
Imposing a very slow speed limit appeared to be a positive move. But is it?
We really have no way of knowing if it has been effective for the simple reason that we don't know if motorists are obeying the limit.
Any reduction in collisions or death or injury could be merely coincidental, or perhaps the vast majority of motorists do stick to the limit.
The reason why we cannot make any judgment on the new limit is because no one is monitoring motorist behaviour in the target zone.
No speed cameras are deployed to check on drivers' behaviour and not a single motorist has been prosecuted since January 31.
It is inconceivable that every driver has stuck to the new limit during the past months, yet there is no obvious deterrent to those who speed.
Police say they don't operate or manage speed cameras in the province and no cameras are deployed within the 20mph zone.
If imposing the limit was an initiative to reduce accidents, it is baffling why there has been no apparent attempt to enforce the new limit and punish those who breach it.
That has led to accusations that there were other motives for the new limit - to make Belfast city centre a cold house for motorists.
There is a policy to reduce the number of drivers coming into the city centre and congesting the streets.
A new rapid transit system is being introduced in an attempt to get more people to use public transport and new bus lanes have been drawn, leading to thousands of drivers being fined for entering them illegally.
Whatever the merits of these efforts to drive motorists out of the city centre, it is difficult to argue against the 20mph speed limit, given the proven correlation between reduced vehicle speed, survival rates and fewer accidents.
Most deaths on our roads - there were 74 last year - occur at high speeds and on rural roads, but any measure which can contribute to increased road safety should be applauded, provided it is enforced.