South West Train study shows numbers without valid tickets
Up to one in 20 rail passengers could be travelling without a valid ticket on some routes, according to new research.
A sample of more than 23,000 South West Trains passengers found as many as 5.5% has not paid the correct fare.
The study carried out in Autumn 2015 found forged tickets, misuse of child fares and passengers using tickets at the wrong time.
The problem is estimated to cost the franchise £25m in lost revenue each year.
The research, carried out for the Department for Transport, estimated the proportion of passengers without a valid ticket as being between 2.7% and 5.5%.
In general, longer-distance and non-London services had lower ticketless travel.
The London Waterloo to Weymouth line saw 1.5% of passengers without the correct ticket, compared with 4.6% on trains from London to Shepperton/Kingston.
Ticketless travel was also found to be most prevalent after 19:00 on weekdays, with an average rate of 5.1%.
The research was carried out over 15 days in October and November.