I refer to Deryk Simpson's letter (NCE last week). The 'Bulleid' 4DD double-deck trains were certainly not overlooked in the recent studies used to develop the SRA's gauging policy.
While it would be fair to suggest that double-deck trains of the types used on the continent would require costly infrastructure works to achieve the necessary European gauge, it would be unwise to rule out the possibility of UK-specific double-deck trains on certain routes.
Modern analytical techniques are able to make better use of our Victorian railway infrastructure. We can now measure it more accurately, model the behaviour of trains passing through it, and understand exactly how much work needs to be done to achieve a safe clearance along the route.
Route capacity is limited by a relatively small number of structures and locations. New technology means that the gauge constraints of the past are not necessarily true today.
The growth in large intermodal rail freight traffic, tilting trains, Eurostar and many modern vehicles has been enabled by these advances in technology on the railways, rather than through wholesale rebuilding. There is no reason why such tools cannot be used to provide new double-deck trains if that is what is required by the country.
David M Johnson (F), managing director, Laser Rail, Fitology House, Smedley Street East, Matlock, DE4 3GH