I'm not sure what sort of evidence would satisfy you, to my mind its more of an issue of logic. Unless you think most of the vehicles that used to use Loughborough Road have just vanished, then its reasonable to assume they are to a large extent the ones currently clogging up CHL.
An hour ago for instance I saw an ambulance, sirens on, lights flashing, moving down coldharbour lane at a snails pace. No place of course for the cars to go to get out of its way.
You know what he thinks. He thinks if you leave the roads closed long enough people will give up and stop driving and then the traffic will all disappear, sorry, evaporate. No doubt he can give you lots of papers with lots of statistics in them to justify that point of view. Of course, in the interim things will be much worse and some number of people might suffer adverse consequences up to and including death on account of ambulances being delayed. But in his world that is "collateral damage" and worth it. The end justifies the means, remember. You can't make an omelette without breaking eggs.