A device is provided to assist the opening of a covering element pivotably mounted relative to an edge of a frame. The device includes an assistance cylinder (6). The assistance cylinder (6) includes a hollow shaft (7), a guide pin (10) inserted in the hollow shaft (7) and comprising at the end thereof opposite the end wall (8) of the hollow shaft (7) a yoke (11), a spring (13) inserted in the hollow shaft (7) surrounding the guide pin (10) and mounted pre-stressed when unloaded between the end wall (4) of the hollow shaft (7) and the yoke (11) of the guide pin (10), and a screw (14) secured to the end of the guide pin (10) and engaging with the end wall (8) of the hollow shaft (7) for keeping the pre-stressed spring (13) in the released state thereof. The invention is useful in the field of road systems.