Safety Manhole Cover / Manhole Cover

We have redesigned the connections of cover and sewer. We installed a plant warning sign which is started by the gravity sensing devices between the cover and sewer. Once the cover is removed, the gravity sensing device senses gravity sharp reduction in short period of time then the warning sign is activated by a chemical reaction and rapidly inflates automatically , pop up and set just above the covers.
Because of luminous paint and bright colors of warning signs surface, no matter in day time or at night, the warning sign can be found and pedestrians will avoid falling into the drainage channel.