.
Note that in this type of ``exploded'' network representation, the itineraries of the transit lines are implicitly contained in the network topology. The set of nodes not only contains the physical nodes of the underlying street or rail network, but also one additional node for each transit stop of each line. Correspondingly, the links are subdivided into various classes, such as boarding, alighting, in-vehicle and walking links. Note that only boarding links imply waiting, thus have a finite frequency 
. All other links are served continuously ( 
).
The waiting time at a node depends on the set of attractive links 
, i.e. the set of outgoing links which are considered for travel by the travelers by boarding the first vehicle leaving on any of these links. For any given set of attractive links 
at node i, the combined waiting time is proportional to the combined total frequency of these links is
and the probability of leaving node i on link a is
Given the above relations, any strategy for reaching destination r i
