Improved Float Bridge (Ribbon Bridge)
The Improved Float Bridge (Ribbon Bridge) Transporter is a modified U.S. Army M812 or M945 chassis with a rear-mounted hydraulically operated boom working in conjunction with an 11,000 pound capacity winch. Each Interior bay contains a four pontoon folding section consisting of two roadway pontoons, divided into two separate water-tight compartments, and two bow pontoons joined together by hinges and pins. The Ramp bay is similar to the interior bay but with two hydraulic pumps mounted beneath the roadway; pumps enable the bay to raise or lower the shore side of the bay from 0-20 degrees to accommodate various bank conditions.
The term "assault float bridge" is strictly a colloquial term generated by years of not utilizing the proper name for this bridge. The correct nomenclature is Improved Float Bridge (Ribbon Bridge) or simply Ribbon Bridge [derived from its automatic unfolding (ribbon-like) characteristic]. The only possible Army bridge still in use that might qualify for the term "assault bridge" would be the Armored Vehicle Launched Bridge (AVLB).
The ribbon bridge is a modular, aluminum-alloy, and continuous floating bridge system consisting of interior and ramp bays that are transported, launched, and retrieved by a transporter/launcher vehicle. Bridge bays, which are carried in a folded position, automatically open upon entering the water to form a 22-foot section of bridge. Under certain raft/bridge designs and slower current velocities, the M1 Abrams tank can cross the ribbon bridge.
Ribbon equipment is designed for use, primarily, during the rafting and bridging phases of the deliberate river crossing. Because ribbon bridges and rafts are significantly faster to construct with fewer personnel than other floating bridges, they are heavily relied upon in this capacity. Site considerations are of primary importance when ribbon equipment is to be used for rafting or bridging operations. Both the launch sites and actual bridge or raft sites should be considered.
Ribbon bridges can be emplaced during daylight hours at the rate of 600 feet per hour or 200 meters per hour. Assembly times should be increased by 50 percent when construction is at night. These times are also based upon the use of an experienced bridge crew for bridge construction under ideal conditions.
The velocity of the river's current can impact significantly upon all float bridging operations. Ribbon equipment can be used in currents of 0 to 10 FPS. Rafting and bridging operations can become quite difficult in currents greater than 5 FPS unless the boat operators and bridge crewmen have experience working in swift currents. For raft sites on rivers with currents greater than 5 FPS, the unloading site on the far shore should be located downstream of the loading site on the near shore to allow for downstream drift.
The ribbon bridge is a floating, modular asset with an integral superstructure and floating supports. Individual bays are joined to form rafts or bridges in support of river crossing operations. Ribbon bridges and rafts provide the maneuver commander with a reliable and responsive means to cross wet gap obstacles from the march.
Ribbon equipment was actually reverse engineered at the United States Army Mobility Equipment Research and Development Command (MERADCOM) at Fort Belvoir, Virginia from photographs and drawings of the Soviet PMP Bridge. Since 1962 the Soviet Army was armed with this type of PMP. The Soviet steeltype Folding Float Bridge designated PMP that was used by Egyptian units to cross the Suez Canal in 1973. The only difference was that the US used duralumin instead of steel for pontoons and installed them on American trucks. The US copy even used the same number of bolts on hatches leading inside pontoons.
The ribbon bridge system was type classified in June 1972, and is currently the United States Army's primary assault floating bridge.
The Upgraded Standard Ribbon Bridge (SRB) provides significant enhancements to the Standard Ribbon Bridge. Its ramp and interior bays feature numerous improvements, such as positive flotation and rapid deployment, and are compatible with Standard bays. In the water, the Upgraded SRB includes special non-skid surfaces, high bow dams to keep water from swamping the roadways and improved folding and unfolding mechanisms to reduce cable breakage. Its sealed hydraulic system uses an environmentally friendly, biodegradable hydraulic fluid. The Upgraded SRB has an 80-ton load capacity for tracked vehicles and a 100-ton capacity for wheeled loads in water velocity of 10 feet per second (3 meters per second). Ramp bays and interior bays are transportable using the Common Bridge Transporter and Bridge Adapter Pallet, an M812/M945-based transporter or other commercial trucks.
Ribbon bridge procurement is complete. An improved ribbon bridge (IRB) is in production by EWK Eisenwerke Kaiserslautern GMBH.
The ribbon bridge provides task force (TF) lead elements with a dependable wet-gap bridging capability that can be emplaced rapidly under all conditions. It facilitates the forward movement across wet-gap barriers of wheeled and tracked vehicles in support of ground combat troops. The bridge system accompanies armored, mechanized, and motorized units and provides wet-gap bridging as required. The bridge bays and ramps are also helicopter transportable.
The Basis of Issue is
- Assault Float Bridge Company, Corps: 30 interior bays, 12 ramp bays, 56 5-ton transporters
- Multirole Bridge Company, Corps Asset, 30 interior bays, 12 ramp bays, 56 common bridge transporters.
Driver skills and training for the transporter and bridging sequence are not significantly greater than that presently required by heavy truck drivers and bridge specialists. Training of crewmembers for the transporter and bridging sequence was accomplished at initial issue. Officer and noncommissioned officer (NCO) training for the ribbon bridge is conducted during basic and advanced courses. Driver's training and all aspects of ribbon-bridge operation is conducted during military occupational specialty (MOS) 12C advanced individual training (AIT) at Fort Leonard Wood, Missouri.
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