CAMP TAQADDUM, Iraq -- Throughout Iraq, military policemen plow like locomotives along highways and dusty trails clearing the path for 1st Force Service Support Group supply convoys.With watchful eyes, the MPs remain vigilant. Roads in Iraq are corridors of danger, laden with tire-popping obstacles and shrapnel-spraying improvised explosives. From palm groves and rooftops, insurgents take potshots with automatic rifles and rocket-propelled grenades.The Corps' cops from B Company, 2nd MP Battalion, based in Camp Lejeune, N.C., and MP Company based in Camp Pendleton, Calif., have spent much of the past six months on the road, logging in tens of thousands of miles to guard the lifeline convoys which haul food, water, fuel and ammunition to Marines operating across Iraq.