Road Surface

In Hong Kong, Highways department is responsible for the repair and maintenance of public roads and ancillary facilities within its ambit. When damages to road surfaces or ancillary facilities are identified during regular road inspections or are reported by the public, appropriate repair works will be arranged taking into account actual circumstances. The following tests are carried out to ensure the quality of the work.

Permeability Test

The permeability test is used to measure the ability of water to pass through the bituminous material. The result is an indication of the field performance of the friction Course.

Sand Patch Test

The method is suitable for the bituminous surface courses and concrete pavement surfaces, it is recommended this testing should be carried out for new roads prior open to use.

Skid Resistance Test

The resistance of wet road surfaces to skidding can be checked by means of a Portable Skid-resistance Tester (Portable Pendulum Tester). It is used to measure the frictional resistance between a rubber slider (mounted on the end of a pendulum arm) and the road surface. The quantity measured with the portable tester has been termed “Skid-resistance” and this correlates the vehicle with locked wheels on a wet road at 50km/h.

Surface Irregularity Test

The rolling straightedge with a 3m straightedge sliding along the road surface. At the mid-point of the 3m length, a sensing wheel mounted between the two parallel rows of supporting wheels is free to move such that its vertical movements are transmitted to two similar pointers on the instrument head graduated scales.

Luminance Coefficient and Retro-reflected Luminance (RL) of Road Markings

Measurement of reflection and retroreflection of a surface involves generally reception of reflected light from a field of the surface when illuminated by a light source. It is used to measure the coefficient of retroreflected luminance with the retroreflected road marking.