In dynamic network traffic loading models with queues spilling back in the links, if one or more links departing a node have demand exceeding capacity, a node model is required to unambiguously constrain the flows exiting the links approaching that node. Basic principles of traffic flow and causality impose requirements on macroscopic node models that have only been recently articulated. Only one existing model fully conforms, but it has a weakness that is identified and discussed. This paper develops a new conforming model from a particular behavior of traffic: vehicles wait their turns to proceed and consume additional approach capacity due to waiting. The model's derivation from behavior distinguishes this model from previous ones that allocate capacity by proportionality rules. A simple, efficient, and convergent solution algorithm for the new model is provided.