One sleeper on its own can be heavy to move around. (120 - 220 lbs) It can trap or break fingers, bruise feet and particular care needs to be taken. Many lorry drivers and workers with railway sleepers have permenantly scarred hands or deformed fingers from being crushed by sleepers.
Take special care when you move or stack sleepers. Wear gloves and serious footware. Be clear with your carrying partner who's lifting first etc. Really concentrate and use correct lifting procedures.

A pile of sleepers may weigh several tons, and if it topples can break legs or seriously injure a child. In the case opposite, it was lucky that only the top of a wall that was smashed. Take special care