Police say there have been three incidents of people trespassing and obstructing the railway line in Stoke-on-Trent in two weeks.
All three happened in the Meir Tunnel area.
In the first incident, which occurred on Monday 29 May at around 6.45pm, a group of around eight youths were spotted by a train driver walking towards Stalington. Fortunately in this instance he saw them in time and was able to stop the train.
The following day another group was spotted at the same location, again the driver managed to slow down.
On Wednesday 7 June, shortly before 9pm a passenger train clipped a shopping trolley that had been placed on the line. Fortunately no one was injured and the train was not damaged in this instance.
Sergeant Gary Matthews said: “The railway is a dangerous place and is not somewhere to hang about or play, you are literally dicing with death by getting too close to the railway.
"Despite repeatedly issuing this warning still some young people either refuse to believe what the consequences can be, or ignore our advice. We need parents and schools on board to get this message home.
“Hanging around near the railway could cost you your life or leave you with extreme injuries. Please parents, speak to your children and teenagers, make sure you explain in as much detail as is needed just how off limits the railway is.
"If it gets the message across then it’s better than having us knock at your door to tell you your son or daughter won’t be coming home. Please, make it your business to know where they are hanging about after school or in the holidays.”
Officers have substantially increased patrols in the area and are visiting local schools to reinforce the message that the railway is a no-go area.
Priti Patel, route head of safety for Network Rail said: “Summer months means we see a rise in the number of young people trespassing on the railway. The railway is not a playground - overhead electric wires and fast trains are just two of the life-threatening risks that trespassers face.
“We work with British Transport Police to stop trespass and help keep people safe. Taking a short cut or messing around on the tracks can result in serious life-changing injuries or death so our advice is simple: stay safe and only cross using clearly marked, public crossings.”