A new node model based on macroscopic model with capacity determination
Despite the results obtained in literature to improve the macroscopic node model it is necessary to consider a general node model approach. A general node approach could take into account different aspects about conflicts at intersections. We present a new node model based on Cell Transmission Model (CTM) to represent traffic flows that crosses signalized and unsignalized intersections. It allows to model complex intersections for urban contest. We have named it, Cell Transmission Model for Urban Traffic (CTM-UT). In particular, to represent different turn movements of the inflow at intersection and belonging at the same lane, the model introduces a new variable. It is utilized to represent the percentages of different turns. The model takes into account also the estimation of the merge flows at the intersection.
The CTM-UT can represent: the connection of the demand upstream intersections to the supplies downstream intersection; the demand percentages of turns for every single lane; complex signalized and unsignalized intersection; merging flows or conflict among crossing flows. In the following example are presents two principal flows and and one minor flow that want cross the intersection at the same time.
A comparison made between CTM-UT and another node model based on gap acceptance, shows that the new node model is suitable to compute the minor streams that are limited by major stream on unsignalized intersections. This model reduces the problems and the complexities of the capacity determination (based on gap acceptance) and it could be used for dynamic traffic assignment. Our model could be used also for complex signalized intersection, where many conflicts among through flows are presented.
More details about CTM-UT can be found on the following paper:
