IT IS always good to see the motoring lobby engaging in constructive debate about road safety. It’s just a shame when the apparent concern over casualty numbers comes across as another lazy pop at 20mph limits and zones (The Argus, July 18).

There will be many reasons for people being killed and seriously injured (KSI) on Britain’s roads last year, possibly including reduced road safety budgets.

Without detailed analysis from Portsmouth, it is impossible to know for sure what the main causes were, or what (if anything) the Portsmouth figures might imply for roads in any other town.

But it would be surprising if increased KSI numbers anywhere in 2011 were found to have been caused by reducing speed limits to 20mph.

Apart from anything else, widespread use of 20mph limits in Portsmouth started as long ago as 2007, so it’s hard to see why there should all of a sudden be a link now between slower speeds and higher KSI numbers.

Closer to home, the scrutiny panel set up in Brighton and Hove by the previous Conservative administration considered the road safety benefits of slower speeds alongside other significant benefits of 20mph limits and zones. These include an improved quality of life, better health, stronger community ties, more social inclusion, a pleasant environment and reduced pollution.

Given all of that, it would be nice to think the motoring lobby could stop quoting statistics out of context, and start accepting the reality of 20mph limits and their benefits for everybody.

Chris Murgatroyd, York Avenue, Hove

IT’S really too soon to use data from 20mph speed limits in Portsmouth to suggest causality. This is because the figures fail to explain: 1) Why the implementation of 20mph limits in 2008 should lead to increased casualties in 2011.

2) Why other towns such as St Helens had higher KSI figures than Portsmouth, yet have not implemented area-wide 20mph limits.

Furthermore, there is, as yet, no breakdown of the Portsmouth KSI figures to indicate the increases were on specific speed-limited roads.

It is important we get a better picture of the 2011 casualties in Portsmouth, because only with a detailed understanding of where those casualties occurred, and the type of road and casualty, can any judgements be made.

For example, it has been suggested these increases may have occurred outside the 20mph zone, which would argue for increasing the area subject to 20mph limits.

Interestingly, Portsmouth was one of very few towns which had no road deaths in 2011. But then, with two deaths in Portsmouth in 2010, the numbers are too low to show any reliable trend between 2010 and 2011.

Portsmouth City Council is currently conducting a full analysis of the 2011 statistics. Until this becomes available, we should not rush to judgement.

And, of course, these figures only relate to one aspect of the 20mph speed limit – they tell us nothing of reduced congestion, improved air quality and increased health and well-being as people shift their transport mode due to the increased attractiveness of walking and cycling.

Stephen Young, Living Streets, Brighton and Hove