The present invention relates to a road manhole of the type defining a centre axis and comprising:                a frame which delimits an opening and which is provided with an internal collar which extends radially inwards,        a cover which comprises a blocking web which is intended to block the opening and a cylindrical skirt which is centred on the centre axis and which substantially complements the internal collar, the blocking web and the skirt defining a concave corner which is directed radially outwards relative to the centre axis, and        a main gasket which is arranged on the internal collar and which is interposed between the cover and the frame when the cover is in a closed position, the road manhole comprising an auxiliary gasket which is, at least in the closed state of the manhole, arranged on the skirt and which is in contact with the concave corner.        
Road manholes of this type are known from the prior art. The main gasket is used in order to acoustically insulate the manhole in the closed state and to reduce the quantity of water which can enter the gap between the frame and the cover, but without ensuring complete fluid-tightness.
The object of the invention is to improve the fluid-tightness of this road manhole, using simple and economic means.