One way to encourage public transportation

You can see the Eiffel Tower -
if you look carefully

Paris imposed a ban on 50% of all cars in the center of the city as a way of lowering severely unhealthy levels of smog. 

Cars with odd numbered plates will drive on odd numbered days - Cars with even numbered plates will be allowed to drive on even numbered days.  Fines will be 22 Euros for anyone driving on the wrong day. 

According to the European Environment Agency (EEA), Belgium, Germany, and France all faced dangerous levels of air pollution with three quarters of France recording PM10 concentrations above the 50 micrograms per cubic meter legal limit. [Business Green]