A timed network is a parallel composition of timed automata synchronizing on common actions. We develop a methodology that allows to use partial-order methods for the reachability problem in timed networks. It is based on a local-time semantics [Bengtsson et al. (1998)]. A new simulation based abstraction of local-time zones is proposed. An efficient algorithm for testing subsumption with respect to this abstraction is developed. The abstraction is not finite in general. We show that, under some weak assumptions, there is no finite abstraction for local-time zones that works for arbitrary networks. We introduce a notion of bounded spread networks, where it is possible to use subsumption and partial-order methods at the same time.