Parents have been warned that children are almost twice as likely to trespass on the railway in the summer than the winter.
Network Rail (NR), which manages Britain's track system, said the longer evenings and extended school holidays "spell danger" for young people.
Analysis of Rail Safety and Standards Board data for 2015/16 showed there are almost 600 trespass incidents involving people under the age of 25 in August, compared with fewer than 300 in December.
Over the past 10 years, almost 170 young people have been killed after trespassing on the railway.
Some 72% of all trespassers killed over the past 10 years were hit by a train. A further 17% were electrocuted - while others fell from structures or trains.
Taking a short cut was the motivation for 42% of trespass incidents, with 19% due to thrill-seeking.
Graham Hopkins, head of safety at NR, said: "We are urging parents to remind their children that if they are on the railway, they are on dangerous ground.
"It may seem like a good idea to take a short cut, or like fun to play on the tracks, but this is not only illegal, it is also dangerous."