cing a transit version of an ``additional options auto assignment''. In the first step of this process, a partial demand matrix representing the trip using a given line (or set of parallel lines) is extracted. In the second step, this matrix is assigned again to the transit network. The resulting boardings to and alightings from the other lines passing at the transfer node can then be interpreted as the line-to-line transfers between the selected line and the other lines calling at the transfer node. While this method does not change the route choice of the trips, it is very time consuming (several assignments needed), it gives only partial information relative to one line and it is only applicable if the line (or set of lines) in question are not used combined with other lines at the transfer node.

In the following sections, we will describe a new methodology designed to overcome the problems mentioned above. The approach allows to compute such line-to-line transfer matrices for selected nodes with the standard EMME/2 software release, as a by-product of a single standard transit assignment. This is done by a special network transformation at the transfer node, which does not alter the mathematical formulation of the transit assignment problem (i.e. yields the same results as before the transformation), but which renders the line-to-line transfers accessible as boardings and alightings of special transfer segments.

Network Representation at Transfer Node

In a standard network, a transfer node is connected by incoming and outgoing links. Each link can carry an arbitrary number of transit line segments and allow a subset of auxiliary modes for accessing to or egressing from the transit lines. For the sake of simplifying the presentation, we assume that all lines actually stop at the transfer node and allow both boarding and alighting. This is illustrated in Figure 1 below:

 

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