Stochastic User Equilibrium Traffic Assignment with Turn-delays in Intersections

Turn-delays in intersections contribute significant to travel times and thus route choices in urban networks. However, turns are difficult to handle in traffic assignment models due to the asymmetric Jacobian in the cost functions. The paper describes a model where turn delays have been included in the solution algorithm of Sto-chastic User Equilibrium traffic assignment (SUE). When the Jacobian is symme-tric, SUE minimises the road users' 'perceived travel resistance’s'. This equals a probit-model where the links cost-functions are traffic dependent. Hereby, overlap-ping routes are handled in a consistent way. However, no theoretical proof of convergence has been given if the Jacobian is asymmetric, although convergence can be shown probable for model data representing realistic road-networks. However, according to the authors knowledge SUE with intersection delays have not prior been tested on a full-scale network. Therefore, an essential part of the paper presents practical tests of convergence. Both geometric delays and delays caused by other turns are considered for each turn. Signalised and non-signalised intersec-tions are handled in different ways, as are roundabouts. In signalised intersections a separate model handles queues longer than one green-period. Green-waves can also be taken into consideration. The model has been tested on a large-scale network for Copenhagen with good results. To make it possible to establish the comprehensive data, a GIS-based 'expert system' was implemented.