Although Roman city traffic WAS notorious...

Explanation: A bit inaccurate in the details - Roman city traffic was godawful. Julius Caesar laid down restrictions on when carts could enter the city of Rome to cut down on the grotesque amount of traffic, and there was a dizzying array of traffic laws and one-way streets in the convoluted metropolis that was Rome. Or, in the words of the Roman poet Juvenal...

Who but the wealthy get sleep in Rome? There lies the root of the disorder. The crossing of wagons in the narrow winding streets, the slanging of drovers when brought to a stand, would make sleep impossible for a [Emperor] Drusus - or a sea-calf.

...

Newly-patched tunics are torn in two; up comes a huge log swaying on a wagon, and then a second dray carrying a whole pine-tree, towering aloft and threatening the people. For if that axle with its load of Ligurian marble breaks down, and pours its spilt contents on to the crowd, what is left of their bodies? Who can identify the limbs, who the bones? The poor man's crushed corpse disappears, just like his soul.