Figure 1: Simple transfer node.
The key idea of our method is to ``blow up'' the transfer node, by adding dummy nodes, links and segments in such a way that:
- The mathematical structure of the transit assignment is not altered. This means that no time or cost element is added and that the new topology still allows exactly the same set of strategies.
- The elements of the line-to-line transfer matrix appear as boardings or alightings at the dummy nodes.
This goal is possible to achieve by using the following transformation: Let's assume that we have
[Page]L lines, numbered 1 to L, passing at a transfer node N. In this case, the node N is transformed into a linear sequence of L+2 nodes connected with links of zero length, i.e.
. All transit lines passing through T are newly routed through these nodes with zero time segments.
is the egress node. All incoming line segments are connected to this node, as well as are all outgoing auxiliary mode links. All lines allow only alighting, but no boarding at this node. Thus, will be used only by trips egressing at node T.
are the line specific transfer nodes. At node 
, alighting is allowed only for line 
