Transport in Antarctica has transformed from explorers crossing the isolated remote area of Antarctica by foot to a more open era due to human technologies enabling more convenient and faster transport, predominantly by air and water, but also by land as well. Transportation technologies on a remote area like Antarctica need to be able to deal with extremely low temperatures and continuous winds to ensure the travelers' safety. Due to the fragility of the Antarctic environment, only a limited amount of transport movements can take place and sustainable transportation technologies have to be used to reduce the ecological footprint. The infrastructure of land, water and air transport needs to be safe and sustainable. Currently thousands of tourists and hundreds of scientists a year depend on the Antarctic transportation system. Land transport Roads Winds continuously blow snow on roads in Antarctica. The South Pole Traverse (McMurdo–South Pole highway) is approximately long and links the United States McMurdo Station on the coast to the Amundsen–Scott South Pole Station. It was constructed by leveling snow and in crevasses, but is not paved. There are flags to mark the road. Also, the United States Antarctic Program maintains two ice roads during the austral summer. One provides access to Pegasus Field on the Ross Ice Shelf. The ice road between Pegasus Field and McMurdo Station is about . The other road provides access to the Ice Runway, which is on sea ice. The road between the Ice Runway and McMurdo Station varies in length from year to year depending on many factors, including ice stability. These roads are critical for resupplying McMurdo Station, Scott Base, and Amundsen–Scott South Pole Station. Vehicles The scarcity and poor quality of road infrastructure limits land transportation by conventional vehicles. A normal car on tires has very limited capability in Antarctic conditions. Scientific bases are often built on snow-free areas (oases) close to the ocean. Around these stations and on a hard packed snow or ice, tire based vehicles can drive but on deeper and softer snow, a normal tire-based vehicle cannot travel. Due to these limitations, vehicles on belts have been the preferred option in Antarctica. In 1997, two specialized cars with very large tires running tire pressure as low as travelled onto the high Antarctica Plateau, giving strong indication that tire based vehicles could be an option for efficient travelling in Antarctica. Mawson Station started using classic Volkswagen