In a warzone, soldiers are trained to watch out for dangerous, life-threatening obstacles. Maybe the enemy scattered landmines around the terrain. Maybe there is a sharpshooter 300 yards away awaiting your approach. Tethered to rooftops in the hot Louisiana sun for the better part of their day, Corps of Engineers Blue Roof contractors assisting with Hurricane Ida disaster response know hidden dangers, too. Their sharpshooter is an unforgiving rusty nail piercing their boot bottom; their landmine is a weak section of roofing with hidden rot under the shingles. Being safe on the ledge of a two-story drop requires vigilance.