"The number of #pollutingvehicles within the #CAZ boundary has seen a huge drop compared to the year before, two thirds of a reduction, or 64 per cent to be precise. Data also shows that the polluting #traffic around the boundary has also dropped by 18 per cent – suggesting that more and more people are making the switch to cleaner vehicles."
I distinctly remember when the 405 freeway in Los Angeles was shut down to build a bridge over it. The newspapers predicted "carmaggaedon", but in practice nothing happened–lots of rerouteing, consolidation of trips, car pooling, and more: traffic evaporation indeed.
And: "Rather than creating chaos, the first closure greatly reduced traffic congestion. Most people chose to cancel trips rather than to reschedule them, but the reductions in travel diminished over the course of the weekend closure as people learned that congestion levels were far below the dire forecasts." https://www.accessmagazine.org/spring-2014/carmageddon-los-angeles-sizzle-fizzle/
What it do is reduce air pollution very significantly: