Network Rail and Southern would like to stress there is no evidence trains are "too heavy" (The Argus, June 10).

The new Electrostars have been used on the Sussex and Kent railway networks for the past 12 months. While they are slightly heavier, they are lighter than other trains using the Sussex network, including freight and engineering trains.

We are monitoring our tracks to see if their introduction has caused any changes. Visual and ultrasonic tests have been carried out on varying sections of the track and the findings show no abnormal changes.

Network Rail is committed to running a financially efficient and safe railway and any money put aside for future maintenance work is prudent.

-Robin Gisby, Operations and customer services director, Network Rail