The Mabey Logistic Support Bridge (in the United States, the Mabey-Johnson Bridge) is a portable pre-fabricated truss bridge, designed for use by military engineering units to upgrade routes for heavier traffic, replace civilian bridges damaged by enemy action or floods etc., replace assault and general support bridges and to provide a long span floating bridge capability.[1] The bridge is a variant of the Mabey Compact 200 bridge, with alterations made to suit the military user as well as a ramp system to provide ground clearance to civilian and military vehicles.
The Logistic Support Bridge is a non-assault bridge for the movement of supplies and the re-opening of communications. It is a low-cost system that can be used widely throughout the support area, as well as for a range of defined applications. All types of vehicles including civilian vehicles with low ground clearances are accommodated.[1]
The Mabey Logistic Support Bridge originated from the Bailey bridge concept. Compared with World War II material in use throughout the world, LSB is manufactured with chosen modern steel grades, with a strong steel deck system. With strong deep transoms, there are only two per bay instead of the four previously needed on Bailey bridges.[citation needed]
Beyond the need for the re-opening of communications, Logistic Support Bridge-based equipment (Compact 200) can be used as a rescue bridge for relief in natural disaster situations or as a civilian bridge for semi-permanent bridging to open up communications in some of the most remote regions of the world.
The bridge is manufactured by Mabey Group at its Mabey Bridge factory in Lydney, Gloucestershire (Mabey Group's original factory, now closed, was in Chepstow and manufactured large bridge girders; in May 2019, the Group sold Mabey Bridge to the US-based Acrow Bridge).[2]
The name LSB was given by the British Army (Royal Engineers) to supply bridging to satisfy their specific requirements for a logistic or line of communication bridging. The LSB went into service with the British Army on 21 December 2001. The system is proved and approved by a number of NATO forces.
Armies from a number of countries around the world own equipment or have trained and deployed on the system, notably during the crisis in the Balkans. These armies include Argentina, Austria, Belgium, Brazil, Bulgaria, Cambodia, Canada, Chile, Denmark, Ecuador, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Malaysia, Nepal, Netherlands, Romania, Sri Lanka, Slovakia, Slovenia, Spain, Sweden, Switzerland, Tanzania, Turkey, Venezuela, United Kingdom, United States.
The bridge has been built in many locations across Iraq and Afghanistan by the U.S. Naval Mobile Construction Battalions (Seabees) and the United States Army Corps of Engineers. During the Canadian OPERATION ATHENA, members of 1 CER on Task Force 3-09 constructed a Mabey Logistic Support Bridge over a pre-existing bridge after a vehicle borne suicide bomb detonated on the bridge close to Kandahar Airfield
The Swedish Transport Administration also uses the bridge where it is used during road renovation and construction or as a stop gap after road damage.[3]
The LSB combines standard off the shelf equipment with a range of purpose designed special equipment to meet the expectations of modern military loads and traffic expectations.
The bridge can be constructed by the cantilever launch method without the need for any temporary intermediate support. This is achieved by erecting a temporary launching nose at the front of the bridge and pushing the bridge over the gap on rollers.
After pushing the bridge over the gap, the launching nose is dismantled and the bridge is jacked down onto its bearings. The launching nose is largely constructed from standard bridge components.
There are a number of floating versions of the Mabey LSB in use across Iraq: Floating Piers which consist of steel Flexifloat pontoon units, Landing Piers consisting of 16 pontoon units, and Intermediate Piers which consist of 8 pontoons each. Hand winches are mounted on steel trays which are bolted to the pontoons. The anchors are connected to the hand winches and pontoons via steel chain and polypropylene ropes. Special span junction decks allow for the rotation of the floating spans as the spans deflect under live load.
If the bridge is relatively short in terms of the number of spans, it may be possible to launch the complete bridge from one bank. On a long span bridge, launching intermediate spans and floating them into position on intermediate piers is more practical.