A method of route determination for mobile elements in a network comprising a plurality of paths each having a predetermined path capacity. The method comprises the steps of registering centrally a plurality of route requests from a corresponding plurality of mobile elements each of said requests defining a journey between an origin and a destination and registering centrally for each route request a journey start time. Routing instructions are centrally determined so as to optimise use of path capacity across all synchronous journeys requests in said network with reference to said registered information, and issued to corresponding mobile elements. The mobile elements adapt their route to comply with the routing instruction. There may be provided further steps of monitoring and rerouting the mobile element whenever new journeys requests can impact its remaining trip.