Road infrastructure networks play an important role in the emergency response to seismic events and related hazards, to ensure both a quick deployment of aids and resources to distressed communities and a prompt repair of the surrounding lifelines and buildings. In this paper, the seismic performance of bridge structures and the functionality and resilience of highway networks are investigated in probabilistic terms. The seismic capacity associated with prescribed limit states, from damage limitation up to collapse, is assessed for bridges included in the network. The level of seismic damage induced by seismic events is related to traffic restrictions involving different categories of road users and a traffic analysis is carried out over the road network to compute the system functionality and the corresponding seismic resilience. The effectiveness of the proposed approach is shown through applications to a reinforced concrete bridge and different highway networks with detours and re-entry links.