I've worked from prints in construction, (HVAC, electrician) and I've got a question and a couple general objections.

1.) Do capacitive touchscreens work through work gloves? I'd use a stylus, but it'd have to be big and thick to use with gloves.

A.) The tablet would have to be waterproof and more durable than the current model ipad. Battery life isn't so much of a problem. (I plug in my flashlight and work phone at the end of the day anyway)

B.) It also has to be cheaper, because ruggedized models will get destroyed anyway. (Dropping them off the tops of scissor lifts, scoring the surface of the screen, etc)

All this seems to imply that wearable displays (ala Rainbows End) would work better for construction.