Road design

Table of Contents

7.2 Stopping Sight Distance on the Major Road and Minor Road

Stopping sight distance along each lane of the major road, the minor road and the ramps should be at least equal to the stopping sight distances given in AGRD 3 (Austroads 2010b) for the appropriate speed. The combined vertical and horizontal alignment and the clearance of lateral obstructions such as walls, bridge piers, noise barriers, landscaping features and safety barrier should be checked to ensure that adequate sight distance is provided and will be maintained.

If minimum stopping sight distance occurs only over a short distance while the remainder of the facility has a higher standard, modifications to achieve a uniformly higher than minimum standard should be considered.

Where the major road (e.g. freeway) passes over a minor road, stopping sight distance along the minor road would usually be adequate unless it is on a curve or stopping sight distance is restricted by a physical object. Wide verges and additional bridge span length may be required to achieve sight distance across the inside of curves.

Adequate sight distance should be provided on the minor road and ramp approaches to at-grade intersections at the ramp terminals. For at-grade intersections the sight distances should comply with the guidelines provided in AGRD Part 4A (Austroads 2010a) and AGRD Part 4B (Austroads 2015c).