This is something I thought about while (surprise) working overtime last night. We should be able to rust worker jobs like roading and irrigation. The extra labor would either be payed for with money or forced labor which would kill the worker, depending on government type. This is really not much different from the way improvements are hurried in cities, but the workers who are putting in the terrain improvements should be able to be rushed, too. Sometimes you really want that road or railroad built as soon as possible.