Why turn it at all? If you just start moving it the other way you won't have the problem of turning. If you really want to turn the box, make sure the hallway

Why turn it at all? If you just start moving it the other way you won't have the problem of turning. If you really want to turn the box, make sure the hallway is wider then 3/4 * sqrt(2) * lengthBox If you turn the box 45 degrees, that's when the box will use the most space. The hallway will have to be 3/4 of the diagonal of the box.