Platoons of connected vehicles can double throughput in urban roads

TL;DR

This paper demonstrates that connected vehicle platooning can potentially double or triple intersection capacity, significantly improving urban road throughput without increasing delays, based on queuing models and network simulations.

Contribution

It provides a quantitative analysis showing how platooning can substantially increase intersection capacity and mobility in urban networks using models and simulations.

Findings

Platooning can double or triple intersection capacity.

Increased capacity does not increase vehicle delays.

Capacity gains are achievable with minimal control impediments.

Abstract

Intersections are the bottlenecks of the urban road system because an intersection's capacity is only a fraction of the flows that the roads connecting to the intersection can carry. This capacity can be increased if vehicles can cross the intersections in platoons rather than one by one as they do today. Platoon formation is enabled by connected vehicle technology. This paper assesses the potential mobility benefits of platooning. It argues that saturation flow rates, and hence intersection capacity, can be doubled or tripled by platooning. The argument is supported by the analysis of three queuing models and by the simulation of a road network with 16 intersections and 73 links. The queuing analysis and the simulations reveal that a signalized network with fixed time control will support an increase in demand by a factor of (say) two or three if all saturation flows are increased by the same factor, with no change in the control. Furthermore, despite the increased demand vehicles will experience the same delay and travel time. The same scaling improvement is achieved when the fixed time control is replaced by the max pressure adaptive control. Part of the capacity increase can alternatively be used to reduce queue lengths and the associated queuing delay by decreasing the cycle time. Impediments to the control of connected vehicles to achieve platooning at intersections appear to be small.