A culvert is a structure that allows water to pass underneath roads or other obstacles. It has a floor, sides and a roof to form an enclosed passageway that is usually circular or rectangular. A culvert qualifies as a bridge when it has more than two large pipes placed side by side to allow a width greater than 20 feet. Bridges are built over large bodies of water to provide passage for people and vehicles, while culverts allow water to pass under obstacles. The key differences are that bridges have no floor and sit on foundations across water, while culverts have an enclosed structure with a floor.

1. a culvert is made to let water pass through an area by making a circular or rectangular passage
underneath a structure, whether it is a road or any other physical obstacle. While in earlier times,
culverts were mostly made of stone, these days it is common to use, cement, steel, or even PVC to
make culverts. A culvert can be circular in shape (semicircular to be precise as there is floor
beneath), or it can be rectangular, elliptical or pear shaped. It is when two or more pipes are placed
side by side in a culvert so as to enlarge the size up to more than 20 feet that a culvert qualifies to
be labeled as a bridge. There have been numerous accidents because of floods disrupting passage
of traffic above a culvert and in a few cases, the culvert has collapsed.
Most of the bridges in the world are constructed over rivers or other bodies of water to provide
passage to people and vehicles. Despite this similarity, there are differences in design because of
differences in terrain as well as materials that are used for the construction of bridges. A culvert
has an enveloping structure with a floor, two sides and a roof. A bridge does not have a floor and
it sits on foundations along the breadth of the water body.
What is the difference between Bridge and Culvert?
• While culverts are used primarily to allow passage of water across physical obstacles, bridges
are formed to provide passage to people and vehicles over large water bodies
• Bridges have no floors, whereas culverts have a floor and are circular, rectangular, elliptical, or
even square in size
• When it is hard to distinguish between a culvert and a bridge, the deciding factors are the width
of the structure.
A pontoon bridge (orpontonbridge) isa collectionof specialized,shallow-draftfloatsorboats,pinned
togetherend-to-endtoproviderigidconnections,andcoveredwithacontinuousdecktoprovide a path
for pedestriansorroadforvehicles.The boatsorpontoonsare liftedby buoyancy,limitingthe
maximumloadtothe total andpointbuoyancyof the pontoonsorboats.
While pontoonbridgesare usuallytemporarystructures,someare usedforlongperiodsof time.
Permanentfloatingbridgesare useful forshelteredwater-crossingswhere itisnotconsidered
economicallyfeasibletosuspendabridge fromanchored piers.Suchbridgescanrequire asectionthatis
elevated,orcanbe raisedor removed,toallow shipstopass.