This Bridge Tank Saves Engineers From Their Deadliest Task
A taxonomy of armored vehicles, volume three—the bridgelayer
The U.S. occupation of Iraq is over. The Afghanistan war is winding down. Today America faces “emerging threats in an increasingly sophisticated technological environment,” according to Gen. John Campbell, the Army vice chief of staff.
For the U.S. ground combat branches that means a renewed emphasis on fast-moving armored warfare. The Army and Marines are dusting off heavy vehicles that played a minor role in Iraq and Afghanistan.
In this series, we spotlight some of the more obscure, and fearsome, armored behemoths. The battle wagons of a new era of warfare. The focus of this volume—the Army’s much-delayed armored bridgelayer.
A river, ravine or anti-tank ditch can bring an army’s coordinated mechanized advance to a grinding halt—and the enemy knows it. Defenders are liable to rain gunfire and artillery down on any engineer attempting to set up a crossing to keep the attack going.
That’s why extending a bridge while under fire is the most dangerous task the U.S. Army assigns to its combat engineers. “The longest 12 minutes of any sapper engineer’s life,” is how Army Capt. Jefferson Mason described the job during a 2012 exercise.
In World War II, armies on both sides outfitted armored vehicles with telescoping bridges. The aim was to give the engineers inside the bridgelaying vehicles some measure of protection while they set up their temporary spans.
Armored bridgelayers remain standard equipment all over the world. But the U.S. Army has struggled to modernize its own bridging gear. For nearly 50 years, the American ground combat branch has used the same AVLB bridgelayer. Following a botched upgrade effort in the late 1990s and early 2000s, today the Army is finally developing a more modern bridger.
The Army’s main AVLB bridgelayer entered service in 1967. The two-man AVLB combines an M-48 or M-60 tank chassis with a hinged arm that extends a 60-foot aluminum span that normally supports vehicles weighing up to 60 tons.
The Army and Marines bought hundreds of AVLBs. But over the decades, the vehicles the bridgelayers supported grew heavier and heavier. The M-1 tank that entered service in the 1980s weighed 70 tons. And the diesel-powered M-48 and M-60 chassis were finding it harder to keep up with the speedier, gas-turbine M-1s.
Plus, the AVLB stores its bridge folded in half atop the chassis—and extends it by lifting it vertically more than 30 feet in the air. In a shooting war, it would be hard to miss. And the AVLB’s armor protection quickly became outdated.
In the late 1990s, the Army developed the M-104 Wolverine—a new bridgelayer based on the most modern M-1A2 chassis. The Wolverine boasted a gas turbine engine, the latest electronics and armor and—most importantly—a more sophisticated bridge arm that extended its span horizontally instead of vertically.
“That unique capability makes the Wolverine a valuable asset, keeping soldiers unseen from a distance as they move across obstacles,” the Army explained.
But the M-104 was expensive. Citing the “affordability factor,” the Army canceled the Wolverine program in 2001. The ground combat branch had purchased just 44 of the more than 400 new bridgelayers it said it needed.
Growing desperate, in 2008 the Army successfully tested the ancient AVLBs for loads of up to 80 tons. But that didn’t solve the old bridgelayers’ speed and vulnerability problems.
Fortunately, the Marines had been tinkering with a new bridging vehicle based on second-hand M-1A1 chassis. Their Joint Assault Bridge was not as high-tech as the Wolverine and lacked the horizontal deployment system. Rather, it extended its bridge vertically, like the AVLB does.
But the Joint Assault Bridge was affordable—a little over $6 million apiece in 2014 dollars. The Army took over the Marines’ program in 2010. Two years later, General Dynamics built two prototypes. And this year the Army requested funding for the first eight production vehicles.
The Army wants 168 Joint Assault Bridges. The Marines want 29. Assuming this bridgelayer effort doesn’t collapse like previous programs, America’s combat engineers finally can rest a little easier at night, knowing they won’t have to suffer their 12 minutes in Hell unprotected.