7.1.1. The sign to diagram 528 (S2‑2‑20, see Figure 7-1) should be used where a hump bridge is so severe that unless drivers are forewarned they might lose control of their vehicles. If visibility is inadequate, double white lines or a hazard line should be laid in accordance with the normal criteria. If the hump bridge hides a further hazard, another sign indicating this should be provided on the same post (with the sign indicating the first hazard encountered placed uppermost). If there is a risk of long vehicles grounding on the bridge, diagram 782 (see 20.4.1) should be used also, mounted below diagram 528. They should be sited, with a distance plate, on the approach to a junction at which vehicles can divert, and repeated at the standard siting distance from the structure (see Appendix A).1%.