  We consider a novel, analytical queuing model for vehicle coordination at
signal-free intersections. Vehicles arrive at an intersection according to
Poisson processes, and the crossing times are constants dependent of vehicle
types. We use this model to quantitatively relate key operational parameters
(vehicle speed/acceleration, inter-vehicle headway) to key performance metrics
(throughput and delay) under the first-come-first-serve rule. We use the
Foster-Lyapunov drift condition to obtain stability criteria and an upper bound
for average time delay. Based on these results, we compare the efficiency of
signal free intersections with conventional vehicles and with connected and
autonomous vehicles. We also validate our results in Simulation of Urban
Mobility (SUMO).
