roadside bombs. carroll spent his first six months here operating a one-man bomb sniffing husky vehicle that the sergeant nicknamed the koch. provised devices hit all but one of the vehicles in i had one hi truck. it wasn't really that significant. still scared the crap out of me, but it wasn't really all that crazy. >> reporter: thanks to armor, carol survived. >> kevlar. >> reporter: but taliban ambushes have claimed victims, including a fellow platoon member who was killed last august. >> yo. >> reporter: nine years ago, allen carol was in seventh grade, waiting for a school bus when he first learned about the september 11th attacks. a lot has changed since then. >> i get nightmares and stuff a lot. but i mean, i'm used to it by now, so i know it's not real, i know it's not happening anymore.