Combat Bridges Shoulder 70-Ton Tanks
Two contractor teams are pitching competing portable bridges to the U.S. Army during ongoing tests at Aberdeen Proving Ground, Md. They are vying for an upcoming contract award to build several dozen bridges-which must be capable of spanning gaps of 150 feet and sturdy enough to sustain a 70-ton tank moving at high speed.
The Army's inventory of bridges includes so-called assault front-line systems, which are launched from a tank, and tactical bridges-deployed by specialized engineer units-that facilitate the passage of tracked and wheeled vehicles. Typically, the tactical bridge units are farther to the rear in the brigade or corps area.
There are two assault bridges currently in use: the armored vehicle launched bridge (AVLB) and the Wolverine heavy assault bridge. Tactical bridges include 1970s systems such as the ribbon bridge, which floats in water, and the medium girder bridge, designed to become a fixed structure. The Army now is seeking to replace both tactical bridges.
Age and Labor
New bridges are needed, officials said, not only because of aging inventory of existing systems, but also in response to the Army's desire to cut back on the manual labor associated with bridge installation and maintenance.
"The ribbon bridge and the medium girder bridge are getting old and are particularly labor intensive to erect," said James Sutton, project manager for heavy tactical vehicles at the Army's Tank-automotive and Armaments Command, Warren, Mich.
In an interview, he explained the Army recently reorganized and created a multi-role bridge company-which replaces two engineer companies-and will be capable of deploying both floating and fixed bridges. "The Army is in the process of activating those companies," Sutton said. The units, under the plan, will be equipped with new bridges. The fixed bridge is called the heavy dry support bridge (HDSB) and the floating system is called improved ribbon bridge (IRB). Either bridge can be transported on one common vehicle.
Four of the companies will be active Army units-two in the United States, one in Korea and one in Germany. The remaining 12 to 16 will be part of the National Guard and Army Reserve.
"The new bridges will support the heaviest loads we have in the Army," Sutton said. That means they must hold up a trailer truck carrying a 70-ton Abrams tank. Existing bridges, which can bear 60-ton loads, can, if needed, allow crossing of a 70-ton tank. "But they have to do it cautiously and go very slowly," Sutton added. "These new bridges will accept the loads at normal speeds."
The Army plans to award production contracts on both the HDSB and the IRB in fiscal year 2000. The service allocated $14 million this year for tactical bridges. The goal is to procure about 100 HDSBs beginning in 2002. That would include four bridges for each of the 16 to 20 multi-bridge companies as well as additional systems for training. The Army also will buy about 200 meters of the IRB bridge for each company.
Two industry teams received development contracts three years ago for the HDSB bridge. Both now are in contention for the production award and have turned over their prototypes for testing by Army officials at Aberdeen. The demonstrations are scheduled to continue through November.
One of the competitors is a St. Louis-based firm called Systems & Electronics Inc. (SEI), teamed with the Swedish firm Kockums Naval Systems, in pursuit of the HDSB award. The other contractor in the competition is Williams Fairey Engineering, a British company.
SEI's version of HDSB is a modification of an existing system in production for the Swedish Army, said Robert Whaley, a company executive. He explained the bridge is designed to deploy in 90 minutes or less with a crew of up to 14. "The program has completed prototype manufacturing, static load testing, and contractor system testing," Whaley said. The HDSB's launching platform is a crane.
While Williams Fairey's HDSB bridge is made of aluminum, SEI's is built with Swedish steel. The Army did not specify one or the other, said Sutton. "We will consider any material," he asserted.
SEI also is participating in the IRB program. For this effort, it partnered with a German firm, MAN Technologie. According to Whaley, SEI produced the launch vehicles for an earlier Army IRB program, which lost its funding several years ago. This time, a work-sharing agreement has been negotiated, he said, and SEI would build much of the bridge in its West Plains, Mo., facility.
The IRB, he added, can be employed either as a full span, floating bridge or configured into rafts to ferry vehicles and equipment across water. It also must be compatible with the Army's current ribbon bridge and bridge erection boats.
Whaley said the current acquisition plan calls for several five-year procurements. "The first multi-year contract for HDSB is planned for 27 systems with a 50 percent option and a current funding line of $131.5 million."
The IRB is procured by sections composed of interior bays and ramp bays. The plan for the first multi-year production of IRB also has a 50 percent option, he said, and the quantities are 226 interior bays and 92 ramp bays. The program's five-year budget is $41 million. The IRB can be used in the form of rafts or bridges of varying lengths, Whaley noted. One IRB kit is made up of 15 interior bays and 6 ramp sections. Small rafts can be used as tug boats to hold it against the water current.
Continuous crossing of vehicles and equipment is enabled by coupling the individual ferries together so that they form a floating bridge. The launching time for the 138-foot bridge is approximately 30 minutes, with a crew of four.
The program currently is not going to go through a competitive prototype phase because that "essentially was done about eight years ago," Whaley added. "The IRB production contract will be awarded without any preliminary hardware testing."
The Army, meanwhile, is moving forward with efforts to upgrade its assault bridges, which support tanks, artillery and infantry on the battlefield. The Wolverine is expected to replace existing armored vehicle launch bridges (AVLB). Wolverine's prime contractor is General Dynamics Land Systems, Sterling Heights, Mich.
The system is based on a M1A2 Abrams chassis with a heavy assault bridge built by MAN Technologie. The aluminum bridge spans about 85 feet and supports 70-ton loads. It can be deployed in about five minutes and retrieved in less than 10 minutes, according to the manufacturer. It is operated by a two-person crew-a driver and a commander who have dual controls to operate the bridge.
The Wolverine is scheduled to begin full-rate production for 465 vehicles in 2001 at a rate of 24 to 36 units annually. In the long term, the Army wants to replace most of its AVLB bridges, which are launched from older M60 or M48 tank chassis.
During bridge deployment operations, the Wolverine drives to the edge of a gap and deploys a spade, located in the front of the vehicle, into the ground to give the vehicle the necessary stability to launch the bridge. The front portion of the bridge slides forward out from underneath the rear portion of the bridge; the rear portion of the bridge drops in line with the forward section and the two are then locked together. The entire bridge slides farther forward, and a hydraulic arm lowers it into place.
The planned allocation is 36 for each Army heavy division. The Army Tank-automotive and Armaments Command awarded General Dynamics Land Systems a $106 million low-rate initial production multi-year contract to build 29 Wolverines. Deliveries of this batch already are under way and will continue through December 2001.