"Railway sleepers" refers to the long and rectangular wooden or concrete beams that are placed horizontally on the tracks to support rails and keep them aligned. Full definition
And then there are the 3,000 sq. foot villas (84 of them) built from recycled railway sleeper cars, volcanic rock and local bamboo. (sandinmysuitcase.com)
The only way to leave the hotel is by a road that looks as though the Romans forgot to finish it, so someone put a couple of railway sleepers down then someone else who does cobbles had a go, then there's a bit that looks like a British council got involved and finally there is a smooth section. (evo.co.uk)
Reuse old railway sleepers laid at single height, cut down or even double stacked to give a defined edge to pebbled or grassy areas. (idealhome.co.uk)