Each type of sleeper will have a slightly different life span due to different preservative treatment and different wood types. A big factor in the life span of railway sleepers is the ground conditions of the installation site and the quality of the installation. Please read our guide on installing railway sleepers on the link below:
Outdoor Oak and softwood sleepers
Below is some general guidance on life span of different sleeper types:
Softwood treated sleepers (Tanalised not dipped) 8 to 10 years
New Oak sleepers 10 to 20 years
Reclaimed sleepers (hardwood) 15 to 25 years
This life spans are greatly affected by the quality of the timber used and the ground conditions so please take care to select the best sleepers which are quite often not the cheapest.