Generalized Network Fundamental Diagram for Motorway Traffic Management

The Network Fundamental Diagram (NFD) has recently gained a lot of attention in urban traffic management due to its effectiveness and parsimony over traditional approaches. Nevertheless, its application on motorways has been limited by the existence of instability and hysteresis phenomenon caused by uneven distribution of traffic. It is recently found that spatial spread of traffic density should also be included when one derives the NFD and this leads to the development of Generalized Network Fundamental Diagram (GNFD) concept. This paper presents an application of GNFD to motorway traffic control. The control strategy presented in this paper consists of an optimizer and a stabilizer. The optimizer regulates the influx to the system during the loading process and aims to maximize the throughput of the system. The stabilizer regulates the spatial spread of the density through applying mainline flow control on various locations along the mainline and aims to reduce the hysteresis during recovery. The method presented herein is parsimonious and novel in the area of motorway traffic management.