They should first figure out how to make average worker spend less than one 55 minutes commuting by public transit each way.
https://www.thelocal.fr/20160418/parisians-spend-23-days-a-y...
https://www.thelocal.fr/20160418/parisians-spend-23-days-a-y...
At the end of the day the only real solution to commutes / crowding is going to be spreading the load out on more communes and cities.