Paris enjoys one of the best public transportation systems in the world. Strikes are not uncommon but when it's running nearly every corner of the city and the near suburbs are served by train, bus, tram and metro, which is by far the most popular mode of transportation. The streets are filled with scooters, motorcycles, cars and, increasingly, bikes but because parking is generally a nightmare in the city, everyone (rich and poor) uses public transportation some of the time. The Ile-de-France is served by metro, RER (a regional express train network) and Translien suburban trains. The RATP, the city’s transportation authority, runs both metro and bus lines and shares control of the RER with the SNCF, the national railway company, who is in turn responsible for all suburban, national and international trains.