The Big Question: Should the speed limit be reduced to 20mph in built-up areas?

Why are we asking this now?

Because an influential traffic safety group, the Parliamentary Advisory Council for Transport Safety (Pacts), has released a report saying that the default speed limit in built-up areas should be reduced from 30mph to 20mph. It has said that this new limit will help to halve the number of deaths on our roads over the next few years. But it is also keen that drivers are made to stick to the new limit, with the use of new speed cameras.

What is this group?

Pacts is a charity, set up 25 years ago to advise the Government on transport safety issues. Its conclusions are only recommendations, and the Government is not obliged to act on them. It does have MPs Peter Bottomley and Louise Ellman supporting it. And as the Government's current targets on improving road safety expire in 2010, it may well be open to new suggestions on how to reduce further the needless deaths and injuries on our roads.

What's the UK's record on road safety?

The UK has managed to tackle road safety quite effectively over the past 20 years compared with some of our European neighbours, with the number of road deaths halving compared with 40 years ago. But 3,200 people still die on British roads each year, and yesterday's report brought attention to the fact that efforts to improve the safety of British roads were "flatlining". It points out that the number of fatalities on our roads has not fallen at the same rate as serious injuries. In particular, the numbers of deaths resulting from drinking and driving, failure to wear a seat-belt, or driving too fast have shown little sign of falling.

Some European nations are outperforming the UK in reducing road deaths. Sweden, the example which many road safety experts say the country should follow, has just 49 fatalities a year per million people, compared with 56 deaths per million in the UK. Also, the Government is struggling to meet its target of reducing the number of people killed or seriously injured in road accidents. It is lagging behind its goal of cutting the number of casualties in the mid-1990s by 40 per cent by the end of the decade. That has led some campaigners to suggest that a change in tactics is needed.

Which roads would be affected by the new limits?

The report's recommendations are that 20mph should be the default speed limit in built-up areas in towns and cities across the country, where the vast majority of pedestrian accidents happen. There are already some 20mph zones, and their number is rising, but in the words of the report, "they remain the exception and not the rule". This is in contrast to some central European cities such as Stuttgart, where 85 per cent of the road network is subject to a similarly low speed limit. If the new proposals are accepted by the Government, local authorities would come under pressure to make a 20mph limit the norm in urban areas.

So, more speed cameras then?

Unfortunately for beleaguered motorists, the trusted speed camera would be the main tool for enforcing any new limits in built-up areas. They aren't just any old speed cameras, though. The committee is recommending that the Home Office pushes ahead with the instalment of next-generation speed cameras, which track a driver's speed over a longer period of time. This could be a more accurate and fairer way of catching the real speeders.

But the addition of new cameras is bound to cause unrest among driver pressure groups and vast swathes of the public, who see the speed camera as a mere revenue-raising device for local councils and the Government. With so many people opposed to the use of speed cameras as a way of cracking down on motorists, the Government may be reluctant to use more.

What's the thinking behind the proposal?

That lives will be saved. And if the report is to be believed, a lot of lives. The aim of the committee is to halve the number of deaths on the roads over the next few years and they see the reduction of speed limits as a key element in achieving this. The reduction could have other implications, too. For instance, it might encourage more people to turn to healthier and greener modes of transport, such as cycling and walking. So it would not just be lives that would be saved – the planet and the NHS could benefit, too.

And though the championing of the 20mph limit was the eye-catching part of yesterday's report, it also suggested a whole host of other measures to tackle road safety, including better town planning and road layout, and the wider use of the so-called "pint of milk test" for new residential housing developments, which takes into account whether the residents would be able to buy a pint of milk in under 10 minutes without having to hop into their car.

Isn't it bad driving that kills people?

That might be a popular slogan for the pro-driving lobby, but it's difficult to argue with the statistics involved in the results of speed reduction. A comprehensive study into the effects of reducing a speed limit to 20mph found that accidents of all types fell by 60 per cent, with accidents involving children down by two thirds.

And the supporters of a wider use of a 20mph limit also have some science on their side. A driver travelling at 20mph is able to come to a sudden stop in almost half the time of one driving at 30mph. The total stopping distance for a 20mph driver is 12 metres, compared with the 23 metres it would take for a 30mph driver to stop.

Opponents of tighter speed limits say that the measures can be counter-productive, forcing drivers to spend more time concentrating on scouring the horizon for speed cameras and keeping an eye on their speedometers, rather than concentrating on the road in front of them.

Are more government measures the answer?

Maybe not. There is some logic to the idea that top-down policies like speed limits, fines and road signs can only go so far in improving safety on the UK's roads. What is really needed to tackle the root of the problem is a change in driving culture, in which drivers are more aware of their responsibilities behind the wheel. That can only be done through education – perhaps as part of the driving test, or even by talking to would-be drivers in schools.

A further danger of applying such strict limits in residential areas is that British drivers simply may not accept them or take them seriously, which could damage the credibility of speed limits more generally.

Is a reduction in the speed limit the answer to making urban roads safer?

Yes...

* Simple physics shows that drivers can react and stop much faster when driving at 20mph

* Research has shown that areas with a 20mph limit have a reduced rate of accidents

* Accidents involving children fall by two thirds in areas with the reduced speed limit

No...

* It is just another way for the Government and local authorities to collect fines from motorists

* A change in culture is needed to stop UK drivers from speeding. Simply lowering the limit will not tackle that problem

* By introducing unrealistic speed limits, drivers may be less inclined to obey limits as a whole