In this paper, the authors report on research that shows that high occupancy vehicle (HOV) lanes do not reduce the capacity of general purpose (GP) lanes. Empirical evidence, complemented with simulations, enable the authors to describe how to estimate total bottneleck capacity and how deploy HOV lanes without hindering vehicle flow. The authors also offer a dynamic strategy that increases a bottleneck's total discharge rate.

The science of cities aims to model urban phenomena as aggregate properties that are functions of a systems variables. Following this line of research, this study seeks to combine two well-known approaches in network and transportation science: (i) The macroscopic fundamental diagram (MFD), which examines the characteristics of urban traffic flow at the network level, including the relationship between flow, density, and speed. (ii) Percolation theory, which investigates the topological and dynamical aspects of complex networks, including traffic networks. Combining these two approaches, we find that the maximum number of congested clusters and the maximum MFD flow occur at the same moment, precluding network percolation (i.e. traffic collapse). These insights describe the transition of the average network flow from the uncongested phase to the congested phase in parallel with the percolation transition from sporadic congested links to a large, congested cluster of links. These results can help to better understand network resilience and the mechanisms behind the propagation of traffic congestion and the resulting traffic collapse.