  Connected and autonomous vehicles (CAVs) improve the throughput of
intersections by crossing in a lane-free order as compared to the signalised
crossing of human drivers. However, it is challenging to quantify such an
improvement because the available frameworks to analyse the capacity (i.e., the
maximum throughput) of the conventional intersections does not apply to the
lane-free ones. This paper proposes a novel theoretical framework to
numerically simulate and compare the capacity of lane-free and conventional
intersections. The results show that the maximum number of vehicles passing
through a lane-free intersection is up to seven times more than a signalised
intersection managed by the state-of-the-art max-pressure and Webster
algorithms. A sensitivity analysis shows that, in contrast to the signalised
intersections, the capacity of the lane-free intersections improves by an
increase in initial speed, the maximum permissible speed and acceleration of
vehicles.
