Currently railway sleepers (in Dutch dwarsliggers) are made of concrete. From a sustainability perspective concrete is not a desirable material because of the high CO2 footprint. By setting up a test-track for sustainable sleepers we challenged different parties to come up with new designs or materialization for sleepers. Setting up an "in service" test-track (where actual trains drive) is a big challenge because of all procedures that are needed to ensure safe driving but it was a necessary step to take in order to change the conservative way of the application of sleepers.