  As a clear signature of modern urban design concepts, urban street networks
in dense populated zones are evolving nowadays towards grid-like layouts with
rectangular shapes, and most studies on traffic flow assume street networks as
square lattices. However, ideas from forgotten design schools bring unexplored
alternatives that might improve traffic flow in many circumstances. Inspired on
an old and almost in oblivion urban plan, we report the behavior of the
Biham-Middleton-Levine model (BML) \-- a paradigm for studying phase
transitions of traffic flow \-- on a hypothetical city with a perfect honeycomb
street network. In contrast with the original BML model on a square lattice,
the same model on a honeycomb does not show any anisotropy or intermediate
states, but a single continuous phase transition between free and totally
congested flow, a transition that can be completely characterized by the tools
of classical percolation. Although the transition occurs at a lower density
than for the conventional BML, simple modifications, like randomly stopping the
cars with a very small probability or increasing the traffic light periods,
drives the model to perform better on honeycomb lattices. As traffic lights and
disordered perturbations are inherent to real traffic, these results question
the actual role of the square grid-like designs and suggests the honeycombs as
an interesting alternative for urban planning in real cities.
