Surface irregularities may be measured using a rolling straightedge. However, a rolling straightedge cannot be used to determine surface regularity where:
The line of a trench is parallel to the centreline of the road for less than 30 m; or
The line of a trench is parallel to the line of traffic flow for less than 30 m; or
The line of a road or trench follows a bend with a radius of less than 250 m; or
The number of surface irregularities recorded along the adjacent road exceeds the upper limit shown in Table S2.3. Where the rolling straightedge cannot be used, the surface regularity must be assessed by another agreed method (e.g. 3 m straightedge).