Curve warning signs can be installed either with or without speed advisory supplementary signs, shown in Table 3‑2 (below). Where a speed advisory supplementary sign is used, the measured advisory speed (VM) is assessed by driving a test vehicle equipped with a ball bank gauge and a calibrated speedometer around the curve at a constant known speed (VO) and observing the highest reading (B), of the gauge. VM is then obtained graphically from Appendix Figure 1: Determination of advisory speed on speed horizontal curves (in Appendix A: Guidelines for the installation of curve warning and advisory speed signs), or by calculation, using the survey values.
Further information for measuring advisory speeds in contained in Appendix A (Guidelines for the installation of curve warning and advisory speed signs).
Appendix A (Guidelines for the installation of curve warning and advisory speed signs)
Appendix Figure 1 (Determination of advisory speed on speed horizontal curves)
Table 3‑2: Typical speed advisory supplementary signs
| Sign code | Example | Description/use |
|---|---|---|
|
W12-3.2 Curve sign supplementary – advisory speed |
 |
May be installed in combination with and below W12-1.1 (L)/(R) – W12-2.4 (L)/(R) signs. The displayed curve advisory speed should be determined by following the advisory speed assessment procedure given in (Appendix A:). Appendix A :Guidelines for the installation of curve warning and advisory speed signs The sign should be installed 100mm below the diamond advance curve warning sign. |
