LET WATER GO / public service design

the innovation of our design(manhole covers)
When there is a need of drainage,it can open some space to drain away water.But when it is idle,the space will shrink to zero mostly,which can keep the bad-smelling gas blocked under ground.Coins,keys or cellphone will not drop into well.we introduce spiral structure into our design,like a pair of Mosquito-repellent incense.There are two parts of spiral that one is fixed and the other is moderately flexible.The rain water produce pressure to the flexible one which will open a modest space for drainage.And the elastic material will also prevent our keys and cellphones from dropping into the well.