Main span means the longest part of the bridge.
The longest single span bridges are suspension bridges. Currently the longest is the Akashi-Kaikyo Bridge in Japan. Its main span is 1,991 metres.
Golden Gate Bridge
The worlds longest cantilever bridge, by span, is Quebec Bridge, Canada at 1800 feet. The second longest is the Forth Bridge, Scotland at 1710 feet
It is the Benjamin Franklin Bridge, with a span of 1,750 feet.
The Akashi-Kaikyo Bridge in Japan
If the question is which type of bridge the answer is a suspension bridge.
16 years
London Bridge spans the River Thames in Central London
1,595 ft and 6 inches
not any more.
The Lake Pontchartrain Causeway (New Orleans)...the World's Longest Bridge. The Causeway is the longest over-water highway bridge in the world.The northbound span extends 23.87 miles and the southbound 23.86 miles.The longest suspension bridge - to date -in America is: Verrazano-Narrows 1298 New York, NY USA 1964 Above graph taken from : http://www.tkk.fi/Units/Bridge/longspan.html