RER A
The RER A has had a significant social impact on Paris and the surrounding region by speeding up trips across central Paris, by making far fewer stops than the Paris Métro and by bringing far-flung suburbs within easy reach of the city centre. The line has far exceeded all traffic expectations, currently serving over 1.2 million passengers per day, on about 300 million journeys per year. That makes the RER A the busiest single rail line outside of East Asia.