Sir – The arguments so clearly set out in Hugh Jaeger’s letter (April 22) explaining some of the important shortcomings of new high-speed rail lines, deserve a wider audience.

The Climate Change Act requires 50 per cent carbon reductions in the next 20 years and 80 per cent by 2050. As the value in early reductions is even more important, the extra carbon emissions relating to travel speed which is relatively quick, cheap and easy to regulate cannot be ignored.

However, Hugh Jaeger did not take his analysis to the logical conclusion by his proposal of a new 125mph line, at which speed trains emit about three times the carbon as the same train travelling at 70mph. Just as he says “125mph are enough to beat 70mph motorways” (and even the enforced speed of 85mph), carbon-efficient 70mph railways would be enough to beat the 50mph or 60mph-limited motorways that have been recommended by the Committee on Climate Change, the Environmental Audit Committee, University College London, the Transport Studies Unit at Oxford University, the Green Party and UKERC.

The Department for Transport has accepted that a reduction to at least 60mph is necessary, but under a Labour administration regarded such a change as “politically impossible”.

Speed is one of the key elements of the transport system and the driver and technology of a car designed for a maximum speed of 60mph would be a much better fit, in terms of efficiency and behaviour, when travelling at 20mph in urban areas than one both designed for, and sometimes driven at, over 100mph.

Daniel Scharf, Abingdon