"A pontoon bridge"
A pontoon is basically a flotation device which has sufficient buoyancy to float itself as well as a heavy load.
In boating terms, it is usually an extension of the shore which you can safely tie a boat to in different ways depending on where you are in the world.This pontoon bridge is generally been made up for the two-wheelers and light vehicles to avoid traffic jams and to avoid other road circumstances.
The mainstream use of these bridges are been done during civil emergencies like river water overflow, heavy traffic, festival jams etc. you may have these sort of bridges in “Kumbh Mela”.