RE: PD Somerville’s letter of last week in which he responded to a previous A De Boise request and outlined why increasing M40 separation distances by painting chevrons would cause ‘total gridlock’.

IN reply to PD Somerville’s letter of December 5, I have no way of knowing whether the figures for peak hour traffic flow that he uses are correct.

I admit at face value the argument is a good one. I can pick a few holes in it though.

Firstly the reliability of his figures depends on how much time he spent during the peak period counting the traffic. It would not be accurate enough to simply multiply a half hour period by four.

Also, the more times the count took place, the more accuracy.

Nevertheless, the figure would suggest that each vehicle must travel at 50-70mph leaving just one car length (not enough) in front.

This is certainly a possible scenario. Personally I don’t travel very often at these times so I am less qualified to assume this happens all the time.

Secondly, although the M40 is three lanes at Handy Cross, it quickly becomes five lanes at Loudwater and is also four and five lanes in other places.

Thirdly, those 25-30,000 vehicles are coming from the Birmingham, Coventry, Banbury, Oxford, Handy Cross, Loudwater and Beaconsfield junctions.

The waiting traffic would be spread out over those junctions.

It would also help if less lorries were allowed on our roads at peak times and when they are they ought to stick purely to the slow lane at those times (where possible).

It doesn’t help when you get a lorry overtaking a lorry, taking four or five times as long as a car.

Another thing that could make a difference is the peak hour mainline trains from Amersham to London are just two carriages long. That really encourages people out of their cars doesn’t it?

The arguments about volumes and peak periods lend themselves to separate arguments about things like congestion, light rail links to Maidenhead and more reliable and longer trains.

I do concede, that with these volumes, the maths do prove that it is impractical to leave two second gaps in peak periods.

However, my point still stands that people ought to obey the two second rule, at the very least at non-peak hours.

During peak hours, people should leave at least a braking distance, instead of blindly assuming that the traffic will keep flowing.

Those who don’t are the people who shouldn't be on the motorway. For those concerned with climate change, the harsher braking and accelerating involved in ‘rush, rush, rush’ driving increases emissions.

If you don’t do it for the sake of other drivers or the environment, do it for the sake of your wallet.

Mr Somerville felt it necessary to say ‘the lower the speed with the same two second separation the less distance between vehicles that so frightens A De Boise’.

Firstly I do realise the distance decreases.

The reason we have the two second rule is to provide a more reliable gap than attempting to estimate lengths in feet or metres.

Secondly, the distance does not ‘frighten’ me.

The point is, that if I have to stop suddenly, I and my passengers will have to suffer the consequences when Joe Bloggs travelling behind smashes in to me. Or some poor soul in another lane will suffer when Joe Bloggs swerves into their lane or their car.

Then you have the tailbacks that ensue from lanes having to be closed while the mess is cleaned up. The point we both missed, which was picked up in Prof Chris Hudson’s letter last week, was that below 70mph chevrons would be useless anyway. I agree with the principle of them though.

A De Boise, High Wycombe.