If there is no time for a round of Transport Fever II, Railgrade is a nice little emulation, containing small scenarios where a certain amount of things have to be moved from a to b to c. Nothing really complicated or hard, but fun and well made.
Train-focused automation with tasks to be accomplished within the given levels in story mode, which I like. Sand box mode for free play and no-pressure enjoyment ist also there. Got it from a reseller for 7 bucks which is an ok price tag imo. Can definitely recommend.