Uruguay, serving long-distance buses that travel into Montevideo, from other parts of the country and abroad. Inaugurated in 1994, it serves more than 12 million passengers per year. Companies opperating at Tres Cruces bus station: URUBUS, Agencia central, Bruno, Copsa, Cromin, Cynsa, Copay, Cot, Cut, Corporacion, Cita, Cauvi, Colonia Express, El Condor, El Norteño, Ega, Expreso Chago, Expreso Minuano, Intertur, Nossar, Nuñez, Rutas del sol, TTL, Turil, Turismar, etc. Aviation Montevideo is served by the Carrasco International Airport , which is located in the north of Ciudad de la Costa, in Canelones Department, from the city center. It handles over 1,5 million passengers per year, and has been cited as one of the most efficient and traveler-friendly airports in Latin America. Ángel S. Adami Airport is a private airport operated by minor charter companies and in which there is also a flight school. Port Montevideo is also served by a ferry system operated by the company Buquebus that connects the port with Buenos Aires. More than 2.2 million people per year travel between Argentina and Uruguay with Buquebus. One of these ships is a catamaran, which can reach a top speed of about .The port on Montevideo Bay is one of the reasons the city was founded. It gives natural protection to ships, although two jetties now further protect the harbor entrance from waves. This natural port is competitive with the other great port of Río de la Plata, Buenos Aires. The main engineering work on the port occurred between the years 1870 and 1930. These six decades saw the construction of the port's first wooden pier, several warehouses in La Aguada, the north and south Rambla, a river port, a new pier, the dredged river basin and the La Teja Refinery. A major storm in 1923 necessitated repairs to many of the city's engineering works. Since the second half of the 20th century, until the 21st century, physical changes had ceased, and since that time the area had degraded due to national economic stagnation. The port's proximity has contributed to the installation of various industries in the area surrounding the bay, particularly import/export businesses and other business related to port and naval activity. The density of industrial development in the area surrounding the port has kept its popularity as a residential area relatively low despite its centrality. The main environmental problems are subaquatic sedimentation and air and water contamination.