Wooden pallet smashes train's windscreen in Ferryhill
A train driver had a "remarkable" escape when a wooden pallet smashed through his windscreen.
The Aberdeen to Penzance service was travelling through Ferryhill, County Durham, when the pallet was thrown from a bridge.
British Transport Police (BTP) said it was lucky there were no "tragic consequences".
A £5,000 reward has been offered for information relating to the 25 August incident.
The pallet was thrown from the bridge at 13.50 BST causing significant damage to the CrossCountry train's windscreen and wipers.
The train continued to Darlington where it was taken out of service.
BTP described the act as "mindless vandalism".
Sgt Cheryl Bainbridge said: "Despite the pallet smashing through the windscreen, remarkably the driver was uninjured.
"This was an incredibly irresponsible and dangerous act, and it was lucky no one was injured or killed.
"It is beyond belief that anyone could put items in the path of moving trains and we need to trace these mindless vandals before their actions result in serious harm to rail staff or passengers."
The driver provided a description of people he saw on the bridge and police spoke to four youngsters in the area who have since been eliminated from the investigation.
CrossCountry managing director, Andy Cooper, said: "The possible consequences of these youth's actions are truly terrifying and it is lucky our driver escaped uninjured.
"These vandals must be apprehended before they cause an injury or worse, and I would appeal for anyone with information to contact the BTP urgently."