Curve chevrons

Horizontal curve chevron boards

The horizontal curve chevron board (W20-1) sign should be located in line with approaching traffic as shown in Figure 3‑2. It should be turned away from approaching driver's line of sight by a minimum of 5 degrees as shown below, but preferably by 10 degrees. Refer to TCD manual Part 1 for sign orientation requirements. The lateral clearance from the edge of the W20-1 sign to the edge of the traffic lane, the edge of the shoulder, the kerb line, or the face of the guard rail (as applicable) must comply with the maximum and minimum lateral offset dimensions specified in TCD manual Part 1. 

TCD manual Part 1

Figure 3-2

The horizontal curve chevron boards should normally be mounted so that the underside of the signs is at least 1.0m above the adjacent sealed road surface. Where forward sight distances are restricted, mounting heights may be increased. Where signs are to be installed near intersections or major accessways, care should be taken to ensure that sightlines are not obstructed.

Chevron curve indicators

Wherever possible, chevron curve indicators (W20-2) should be mounted at a constant height so that the undersides of the signs are at least 1.0m above the adjacent sealed road surface, and at a constant lateral distance from the edge of the adjacent traffic lane to ensure approaching drivers are given the best possible visual indication of the curve’s horizontal and vertical alignment (where there is a risk of vehicles colliding with any sign, the supports for those signs should be of a breakaway or yielding design).

At least three W20-2 signs should be provided for each direction of travel. They should be installed at equal spacing on the outside of horizontal curves and in such a manner that, while traversing the curve, drivers will always have at least two in view (refer to Figure 3‑3). Where forward sight distances are restricted, mounting heights may be increased to have two in view. Chevron curve indicators should be located in the following manner:

• the first chevron curve indicator on the approach to a horizontal curve:
  • left hand curves:
    • two-way two-lane roads: On the prolongation of the centre of the lane; and
    • one-way roads: On the prolongation of the right-hand edgeline or the right-hand edge of the sealed road surface if the edgeline is not marked; and
  • right hand curves:
    • on the prolongation of the left-hand edgeline or the left-hand edge of the sealed road surface if the edgeline is not marked; and
  • when a horizontal curve chevron board is warranted it will replace the first chevron curve indicator described above and it should be located as illustrated in Figure 3‑2;
    Figure 3-2
    and
• the last W20-2 sign at the end of a horizontal curve should be located at the tangent point of the curve, regardless of whether it is a transition curve or a simple circular curve; and
• intermediate chevron curve indicators should be located as follows:
  • on the outside of the horizontal curve; and
  • at equal spacings between the horizontal curve chevron board and the last chevron curve indicator located as specified above at the end of the curve.