Currently, an average of over 100,000 vehicles use the Golden Gate Bridge every day. Approximately 40 million vehicles used it in 2003, which is not much more than its first year’s volume of 33 million. There have been over 1.8 billion crossings since it opened in 1937. It has been closed only three times because of high winds (mostly to protect motorists from wind-whipped trucks) since it opened, once each in 1982 and 1983, and once in 1951, when 62 mph winds caused slow vibrations that threatened to damage the roadbed – a large project then began to add more structure under the roadbed to stiffen the structure against the wind, which appears to this date to be great success. It has been closed to traffic briefly for various construction projects and to vehicles on special occasions, such as its 50th Anniversary Celebration.