Why do some vehicles overlap in queue?
Most likely the length of the link as drawn by TRAFVU is shorter than the link length input for the link. You can check this by right-clicking on the link and selecting the Geometric Data item while in TRAFVU. Both the TRAFVU calculated length and the input length are displayed. Remember that the link length is measured from upstream stop bar to downstream stop bar, not from node-to-node. There can be quite a discrepancy between those two distances when the upstream and downstream intersections are not similar. This is not only a drawing issue but can affect your link storage if not corrected. CORSIM uses the link length from Record Type 11 when determining how many vehicles can be on the link, not the node-to-node distance.
