Up to now, EMME/2 offered two choices for defining the times on auxiliary transit links: either using a mode specific constant speed or using a mode specific auto time factor. Usually, constant speeds are used for walk and bicycle type auxiliary transit modes, whereas the auto time factor is particularly suited for motorized access modes, such as park&ride or feeder bus lines.
While these two possibilities cover well the needs of most applications, there are some types of models in which auxiliary transit times need to be specified explicitly at the link level. In particular, this is the case for models which are concerned with the congestion on auxiliary links, such as modeling the access to railway platform or the pedestrian tunnels connecting two subway lines.
For such applications, Release 9 offers the new
possibility to tie the travel times of an auxiliary transit mode to
one of the three link user data items ul1, ul2 or ul3.
Link specific auxiliary transit times are specified at the mode level
in module 2.01. This is done by entering (interactive or batch entry)
a time factor of the form ulX*factor.
The auxiliary transit times are then computed as the product of the
link user data item ulX times the specified factor.
If e.g. the link specific auxiliary transit times for walking are stored
in link attribute ul3, the time factor for the walking mode would
have to be entered as ``ul3*1''. The possibility of having, in
addition to the attribute itself, a mode specific time factor allows
using the same attribute for several auxiliary transit modes,
but with different ``weights''.