The Japanese are very risk averse people. There is a belief that Japan is a very dangerous place, and each and every potential threat must be protected against. This is why stores wrap goods in far too much bubble wrap and paper (they might break), why every river bank is covered in concrete (it might flood), and why guards with illuminated batons line construction sites (someone might get hurt).
Below a live guard is assisted by a mechanical one to direct traffic around glow cones spaced every meter. An over abundance of signage point the direction and warn of impending danger.
Generally, I nod politely to the guards, thanking them for protecting my safety.