There’s still construction and reconstruction in downtown Houston. This hallway was created to shield the walking public from potential falling glass. There’s quite a few of these temporary structures, no doubt in place to prevent litigation, and they spring up overnight. I imagine they are pretty simple to construct, and look pretty solid for metal scaffolding and plywood.
Naturally this would have to go in my mental toolbag for the coming zombie apocalypse. These structures can stand up to constant Romero zombie pounding, but would probably be useless in the long term against fast zombies, Infected, or those wearing headcrabs. But in a Romero style outbreak, these could be built inside any building and pushed out of a door. Some scaffolds have wheels, so this would be relatively easy. A long enough tunnel could then reach across the street, so you could then go secure the other building. Two tunnels could block off the street itself, and you could then clear it and open up, build an internal permanent defense, break down the tunnels and repeat elsewhere on your block. Eventually over time (and what else do you have during the zombie outbreak?) you could clear a significant portion of any city with these, if you have enough of it.