The Engineer Bridge-Launcher Incident

Vietnam-era tale from the field
Author:
Updated:
Original:
 Soviet MT-55 at the Militärhistorisches Museum der Bundeswehr in Dresden, Germany. During the 1960s, US forces had captured one of these in Vietnam. They sent it to the home of the Corps of Engineers at Fort Belvoir, Virginia, for “reverse engineering.”

Soviet MT-55 at the Militärhistorisches Museum der Bundeswehr in Dresden, Germany. During the 1960s, US forces had captured one of these in Vietnam. They sent it to the home of the Corps of Engineers at Fort Belvoir, Virginia, for “reverse engineering.”

During the mid-to-late-1960s, the unpleasantness in Southeast Asia was getting serious. The Soviet military was sending war material, advisors and troops to North Vietnam. At that time, the United States was also sending war material, advisors and troops to the South Vietnamese Army.

At the time, the U.S. Army’s Corps of Engineers was interested in the Soviet Scissors Bridge Launcher. This type of vehicle consisted of a folded highway bridge mounted on a track-laying, army tank chassis. Here’s how it worked:

The bridge launcher drove up to a bank on a river. The operator unfolded the hydraulic-assisted scissors bridge over the river to the other bank. Then, the operator uncoupled the tank chassis from the foot of the bridge, only to drive it over the freshly deployed bridge. This leadthe way for subsequent vehicles to follow. And, this could all be done under fire — it’s a tank, after all!

A CAPTURED BRIDGE

U.S. forces had captured a Soviet-supplied scissors bridge launcher in Vietnam. Still operable, the bridging unit was sent to the home of the Corps of Engineers at Fort Belvoir, Virginia, on the west bank of the Potomac River. The Engineer Research & Development Laboratories (ERDL) were tasked with testing and reverse-engineering the Soviet vehicle. The engineers had to find out how it functioned, and just how the Red Army vehicle compared to the Army’s own bridge-launching vehicle, the M60-based Armored Vehicle Launched Bridge (AVLB).

 The US Army finally deployed the M60 AVLB in 1967. it is an armored vehicle based on the M60 Patton main battle tank chassis and was used for the launching and retrieval of a 60-foot scissors-type bridge. The AVLB consisted of three major sections: The launcher, the vehicle hull, and the bridge. John Adams-Graf Collection

The US Army finally deployed the M60 AVLB in 1967. it is an armored vehicle based on the M60 Patton main battle tank chassis and was used for the launching and retrieval of a 60-foot scissors-type bridge. The AVLB consisted of three major sections: The launcher, the vehicle hull, and the bridge. John Adams-Graf Collection

The Engineers removed the scissors bridge structure from the Soviet vehicle. After tests on the tank chassis were finished in the Cold-Room Laboratory, the vehicle had to be moved to a nearby hanger for follow-on-testing. When the regular technician couldn’t be found to move the chassis, the project engineer, under pressure by “higher authority,” went to the Cold-Room lot, fired up the tank engine, and proceeded to drive the vehicle back to the hanger.

Because the US Army officers (“green suiters”) were heavily micro-managing his project, the engineer knew he had to do everything swiftly to keep folks off his back. He was also aware that he was not licensed to operate this tracked vehicle. Regardless, he had less than a mile to drive back to the hanger.

What he had not realized was that all of its Army lives had not been kind to this vehicle — neither the Red Army, the North Vietnamese Army, nor the US captors. In addition, captured enemy equipment rarely receives prudent Preventive Maintenance service. The Soviets hadn’t supplied the required operational or repair manuals, either!

The steering system was tricky. The launcher was steered by levers, de-clutching engine power plus braking the tank tracks curbside with the right hand track or roadside with the left. The mechanism had badly deteriorated. For the operator, the trick was to anticipate all turns.

Deterioration was such that when the project engineer pulled on either steering lever, the captured launcher proceeded on its own, straight-ahead path for several seconds until actually obeying the steering input. Likewise, after such turns when the steering lever was released, the launcher took her own sweet time before the turning ceased, and a straight-ahead path was renewed.

The engineers and technicians at the laboratory parked their cars, side-by-side in spots in front of their office and hanger. To avoid traffic tie-ups at quitting time, it was good practice to back into the spot to have the front of the cars ready to drive out.

On this particular day, our project engineer had arrived early. He had found the prize parking spot, ready to merge into traffic at 1700 hr. He backed his new Mercury V8 sedan into the coveted parking spot on the curve near the end of the parking area.

 M60A1 AVLB is the upgraded version based on the M60A1 MBTs chassis. The roadway width of the AVLB is 12 feet 6 inches. During deployments, bridge emplacement can be accomplished in 2 minutes, and retrieval can be accomplished in 10 minutes under armor protection. Photo by John Adams-Graf

M60A1 AVLB is the upgraded version based on the M60A1 MBTs chassis. The roadway width of the AVLB is 12 feet 6 inches. During deployments, bridge emplacement can be accomplished in 2 minutes, and retrieval can be accomplished in 10 minutes under armor protection. Photo by John Adams-Graf

Meanwhile, the engineer who had decided to move the launcher on his own was driving down that same road on his way back to the hanger to continue his tests. At one point, he encountered a 45-degree, right-hand curve in the road. He pulled back on the right hand lever. The launcher went straight ahead for about five seconds before the right turn clutch disengaged. Then, suddenly, the launcher lurched into a right hand turn — much sharper than the engineer had intended! This was the setup for a disaster.

The Soviet bridge launcher aimed herself along the right shoulder of the curve. It just so happened there was a brand-new Mercury parked on that curve! The bridge launcher’s right track climbed up on the front that new Mercury before the poor project engineer could do anything to stop it.

The weight of the tank track crushed the front the Mercury until it was no higher than 18 inches from the ground. The tires and wheels, suspension and frame, and the V8 engine block with hood plus fenders were mashed into a solid block of metal. At least, the launcher brakes worked, even though a bit late.

Of course, ERDL security officers immediately closed off the road, secured the area, and began documenting the scene of the accident. Even the air had a smell of “Top Secret” and “Need to Know.” The very existence of a Soviet scissors bridge launcher could not be discussed — it was captured war material.

The project engineer called his car insurance company. He spent time trying to convince his agent that this was not a practical joke. He even had his fellow employees confirm the incident: “On Fort Belvoir Post, a Top Secret, End Item had crushed, and completely flattened the front end” of his new Mercury.

After two weeks of investigation, the US Army winched the Mercury up onto an M172 25-ton low-bed trailer. The car, tied down, was towed outside the ERDL Main Gate. There, the insurance agent took photographs of the Mercury’s front end damage. The engineer provided the agent with the Army’s Accident Report. Of course, most of the report was blacked-out because of the sensitive nature of the Top Secret, Soviet Scissors Bridge Launcher.

Through the combined efforts of the insurance company and the U.S. Army, the project engineer’s claim was settled. He was driving a new Mercury sedan within six months. The insurance company never knew what kind of heavy item could flatten the whole front of a car to within 18 inches of the ground!