U.S. combat engineers clear the way for Afghanistan withdrawal

(CBS News) Forty thousand American troops and hundreds of tons of equipment will leave Afghanistan over the next year, but they face one final threat: roads filled with explosives.  A platoon from Fort Hood, Texas is working to get some of them home safe this Thanksgiving weekend.

Correspondent Charlie D'Agata went along with them, one day after a roadside bomb killed 18 Afghan civilians on a bus. 

Roadside bombs are the biggest killer in Afghanistan. The threat of improvised explosive devices is the reason why U.S. soldiers alone -- like those from Fort Hood -- make the final sweep of any road used by American forces.

It's the one military operation that's not done alongside the Afghan Army.  

U.S. soldiers search for hidden wires that Taliban fighters use to trigger the bombs.

“Mostly they use lamp cord wire,” Sgt. Keenan Roberts told D'Agata. “Really fine copper wire; we call it angel hair.”

The last time Roberts and his platoon from the 8th Engineer Battalion were here, they walked straight into an ambush. His soldiers escaped without injury. He says he wants to keep it that way.

“You want everybody to walk off that plane back in Texas with all their fingers and toes," he said. "We want to go back as a group. We don't want anybody getting hurt and going back by themselves.”

As U.S. troops hand over security responsibility to Afghan forces, they travel on far fewer roads. Taliban fighters know this, and they're concentrating their efforts on those routes.

Commanding officer Capt. Andrew Elliott said he worries every time he sends his men outside the base.

“No matter the training, there's still that threat. No matter how much body armor you're wearing, that bullet, that fragmentation can find its way to those hotspots that's not covered. So you just worry, period, about your guys and gals that are on the front line, fighting everyday.”

He told D’Agata that there’s never a down day, and it never becomes commonplace.

“Especially for route clearance -- for us, it's every day, go at it, find the IED, keep the roads open, keep the roads safe.”

Now with the U.S. draw-down gathering speed, keeping the roads safe for those forces is getting tougher every day.