I think you probably mean "bridge span" rather than "spam bridge." A bridge span is the part of the bridge between its supports.
We may suggest 20ft (6m) to be the criteria but i insist this is practically too short. Bridge span of 20meters or less may be a good standpoint reference of "short span".
for short distance half circle bridge is better and for large span flat bridge is used.
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.
its the span of a bridge for which the cost of building both substructure and superstructure is same....
A span of gap is something in a gas leak or under a bridge that smokes.
the span
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.
Span is a verb, noun, and an adjective. verb - The new bridge will span the river. His acting career spanned 55 years. noun - I talked to him over a span of six years. Small children have a short attention span. adjective - Her apartment was always spick and span.
They are less likely to be hit by waves Short span beam bridges are very strong.