Sir – HGVs are about four per cent of road traffic but cause about 45 per cent of road wear.

HGVs produce three times as much CO2 per tonne-mile as rail freight. We must switch freight to rail as much and as swiftly as possible to save our roads and environment.

In 2011, Network Rail (NR) finished its £55m loading gauge enlargement between Southampton and Nuneaton. This extra headroom lets trains take 9ft 6in-high cube containers on standard wagons, increased freight on the route by 35 per cent within a few months and cut the number of HGVs on the A34. To run a two-track railway well, freight trains wait in passing loops as passenger trains overtake. The number of loops determines how many freight and passenger trains can share a line. The length of loops determines how long freight trains can be.

Loops on the route between Southampton and Nuneaton allow 500-metre trains but NR is lengthening them for 775-metre ones. This will raise the number of containers per train from about 80 to over 120, further reducing HGVs on the A34. In August, you reported that residents beside the railway between Oxford and Wolvercote welcome Network Rail’s reinstatement of a fourth track there to extend such a loop.

Christmas gives a rare few days without trains that NR often uses for big engineering works, including overnight. This included bridge replacement at Reading at Christmas 2011 and Sonning at Christmas 2012.

This Christmas NR will install points at Wolvercote linking the extended loop with the main line. David Gautrey regrets the loss of trees at Wolvercote. They were cleared to make enough working space to restore the fourth track. They were a few metres deep, which was not a noise barrier. Trains were already visible from much of Port Meadow, so increasing their visibility from Wolvercote Common is unremarkable.

Hugh Jaeger, Media relations officer, railfuture Thames Valley Branch