If using TRANSYT 13 you need to set the saturation flow to a high value to avoid unrealistic queueing.
If using TRANSYT 14 or TRANSYT 15 you can set the link saturation flow to “unrestricted”. This gives it an infinite capacity, therefore avioding any queueing. This feature is particularly useful when adding exit links to your network which you don’t want queues forming on, and influencing the network timings.