A river crossing requires specific procedures for success because the water obstacle inhibits ground maneuver in the usual way. It demands detailed planning and different technical support than other tactical operations. Extensive use of corps engineer assets are required. It is critical for supporting corps engineers to be totally involved in all facets of the river-crossing operation from initial planning through preparation and execution.
A bridge operation requires a continuous traffic flow to the river. Units must be briefed and sent to the crossing site quickly. To accomplish this, engineers brief at staging areas and check vehicle load classification and dimensional clearances. Vehicles maintain a maximum speed of 9 kph while crossing the bridge. Vehicles must not stop on the bridge. Operators must not shift or make abrupt changes in speed on the bridge. Vehicles maintain the interval indicated by signs on the side of the road. Operators follow the signals of engineers at ramps and intervals along the bridge.
Organizing and training for war fighting remains the primary mission of Army engineers. However, engineers can be called on to conduct contingency operations. For example, US Army operations in Bosnia included the mission to bridge the Sava River near Zupanja, Croatia, in December 1995. This mission was the largest river-crossing operation since World War II and was conducted under extreme conditions. Seasonal weather caused the Sava river to swell from its normal width of 300 meters to more than 600 meters. Despite harsh conditions, engineers used Chinook helicopters to deploy ribbon-bridge sections into the river while other engineers rebuilt the approaches and successfully bridged the Sava river to allow elements of the 1st Armored Division to cross. As the floodwater receded, engineers built a causeway across the floodplain. As operations in the area continued, the ribbon bridge remained the only crossing means for both military and civilian traffic while preparations were made for fixed bridging.
Versatile engineers provide unique personnel and equipment capabilities that can effectively support complex and sensitive situations in any contingency operation. Therefore, engineer force-projection planning should include the possibility that forces committed to contingency operations may become involved with combat operations. The engineer commander tailors engineer support based on contingency-operation requirements, which may be radically different than supporting combat operations. In many cases, the only difference between a wartime and an engineer contingency operation is the threat level.
Contingency operations may require the same or a greater level of logistics support to engineers as wartime operations. Combatant commanders tailor logistics support to engineers based on theater needs. Logistics efforts are integrated with host-nation or local resources and activities. Engineers invariably get involved with a wide variety of gap-crossing operations that may need flexible logistics support.
The AVLB is an organic engineer asset that travels with maneuvering armored and mechanized infantry formations and can quickly gap up to 15 meters for 70 MLC vehicles. The assault launcher can launch the bridge without exposing bridge personnel to enemy fire and can retrieve the bridge from either end. The Wolverine will eventually replace the AVLB. The Wolverine will consist of an M1- series Abrams tank chassis modified to transport, launch, and retrieve a MLC 70 bridge. The bridge will be capable of spanning at least a 24-meter gap.
Floating bridges are the primary means to cross the force and its supplies rapidly. The same units that provide heavy rafts also provide float bridges. The ribbon bridge is the primary assault bridge because it is quick to assemble. Ribbon-bridge operations normally last no longer than 72 hours. Having the ribbon bridge remain in operation beyond that time frame presents problems for the engineers that normally would not be experienced during a short duration. Equipment maintenance, anchorage systems, constant changes in the water level, and repair of approaches must be considered for long-term use of assault bridges. As equipment remains in use during crossing operations, maintenance services become more difficult to manage. The M4T6 would replace the ribbon bridge to allow the ribbon bridge to continue to move forward with the advancing force. Because it is man-power intense, the M4T6 is slower to assemble than the ribbon bridge. Preassembly of the M4T6 floats in rear areas significantly reduces the final assembly time on the river.
Fixed bridges rest on the riverbanks and intermediate supports instead of floating on the water. They span ravines as well as rivers. They have limited use for the initial assault because they are slow to assemble and vulnerable to enemy action. Where appropriate, fixed bridges supplement or replace float bridges. Engineers also use fixed bridges to repair existing damaged bridges. The rapid construction characteristics of the MGB versus the Bailey bridge provide it with a better capability that can be used well forward in the main battle area. Since the Army does not currently have a tactical dry-gap capability longer than 60 feet, using the MGB in this role becomes an important operational consideration. The primary role of the MGB is for tactical bridging in the brigade area, while the Bailey bridge is used primarily as a LOC bridge. As the tactical situation permits, the MGB is removed and replaced by Bailey, timber, or steel bridges.
