In this note, we describe an implementation of an equilibrium transit assignment based on the concept of optimal strategies. The congestion is modeLED by means of volume dependent cost functions, similar to the volume-delay functions used in the highway equilibrium assignment. After having presented the mathematical formulation of the model, we discuss its implementation in EMME/2.
Fixed Cost Assignment Model
In this section we briefly describe the fixed cost transit assignment model based on optimal strategies. For a more detaiLED description of the model, as well as the proofs, refer to Spiess (1984) and Spiess and Florian (1989).
For the sake of easier presentation of the mathematical formulation of the model, the transit network is assumed to be represented by a standard node/link type network, where a set of nodes 
is connected by a set of links 
. The set of links going out of node i (forward star) is denoted 
, and the set of incoming links (backward star) is denoted 
.
A travel time (or cost) 
and a service frequency 
is associated with each network link
