Every tank force that is heading to its objective is going to roll in to obstructions, be it man made, such as a destroyed/disabled bridges or by mother nature, this being rivers/water ways or breaks in the ground, which prove to much for a tanks mobility.

This means it needs a vehicle capable of laying down a bridge that can gap these obstructions, so the tank force can cross them. This means the vehicle has to be capable of keeping up with the tanks, so its best to use the tanks chassis/hull/automotive components with the bridge mounted on it.

The Russian MT-55 AVLB is a scissor type bridge mounted on the hull of the most heavily manufactured tank in the world, the Russian T-55.

The MT-55 span is 18 meters long and can hold up loads up to 50 tons. Later Czechoslovakians modified their MT-55s with gap measuring mechanism and infrared equipment for bridge laying at darkness and named those as MT-55A.

The Russian MT-55 AVLB Versions:

MT-55A – Czechoslovakian redesigned version MT-55
MT-55K – Improved version of the MT-55A
MT-55L – Version capable of using longer version of the MT-55K bridge

The Russian MT-55 AVLB MT-55 Operators:

Egypt
Georgia
North Korea
Russia
Syria
Israel

MT-55A Operators:

Czech Republic
Romania
Serbia
Slovakia
Sri Lanka

The Russian MT-55 AVLB Spec’s:

Weight – 36 ton
Length – 9.88m (with in deployed bridge)
Width – 3.3m (with in deployed bridge)
Height – 3.35m (with in deployed bridge)
Crew – 2 (commander, driver)
Engine – Model V-54 or V-55 12-cyl. 38.88 litre water-cooled diesel 520 hp (390 kW)
Power to weight – 14 hp/tonne
Suspension – Torsion bar
Operational range – 750 km (On roads), 500 km (Off-road)
Top speed – 50 km/h