A bridge spans a river from one bank to the opposite bank. So the span is the distance the bridge must stretch.
I think you probably mean "bridge span" rather than "spam bridge." A bridge span is the part of the bridge between its supports.
Main span means the longest part of the bridge.
span bridge
A bridge's span is the length that crosses the gap.
The span is the distance between supports. The sum of the span lengths is the bridge length.
the span
A span of gap is something in a gas leak or under a bridge that smokes.
its the span of a bridge for which the cost of building both substructure and superstructure is same....
Tsurumi Tsubasa Bridge has a center span of 890m making it the largest bridge in the world!
Akashi-Kaikyo Bridge, Japan is the longest single span bridge which is 1,991 meters long.
That is the correct spelling of "span" (a distance, or to 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.