Surveys

High Speed Surveys

HDS are at the forefront of asphalt laser surveying, having developed systems that directly replicate volumetric patch texture and rolling straight edge tests. Our laser systems are vehicle mounted, removing technicians from harm’s way and delivering high-quality accurate testing from the safety of a vehicle. HDS also provides advanced surveying capabilities for measuring road surface characteristics during the asset lifecycle, including SMTD, MPD, IRI, and Grip Testing.

Traffic Speed Surveys

Highway Data Systems have a number of surveying capabilities including:

  • Surface macrotexture - volumetric patch / sand patch /glass beads test equivalent
  • Surface profile (rolling straight edge equivalent)
  • Grip testing and SCRIM equivalent conversion
  • International Roughness Index
  • Sensor measured texture depth (SMTD) and Mean Profile Depth (MPD)

Surface Regularity and Surface Macrotexture

The HDS laser survey systems directly replicate the volumetric patch test for asphalt surface macrotexture and the rolling straight edge test for asphalt surface profile. These two tests are currently undertaken using traditional manual methods which pose a serious risk for the people doing them and which deliver unreliable and undigitized report data.

The rolling straight edge equivalent laser is a single point red laser which measures, over a 3m period, the surface linear profile of an asphalt or concrete road surface. The HDS texture laser operates by inverting the usual texture equation whereby a known volume of either glass beads or sand is spread out over an asphalt surface and the diameter of the resulting circle is measured to infer the surface macrotexture.

The HDS blue laser system is approximately 200mm wide and, by travelling longitudinally along the road surface measuring at 62,000 times per second, calculates the volume of the surface. Research funded by National Highways has demonstrated equivalence between the conventional and HDS methods and HDS now operate the laser system on a number of sites on the Strategic Road Network, the Transport Scotland Trunk Road, and several UK local authority sites.

Grip Testing

HDS use a Findlay Irvine MK2 Grip tester and survey for grip number in accordance with BS 7941-2:2000.

Grip is a significant factor in road skid resistance* and HDS offer a a quick and efficient service that can test small or large sections of road at traffic speed. The test involves towing a specialist trailer that measures the grip of the road as it moves. This test is conducted at traffic speed and does not require any expensive road closures or traffic management. All data collected is geo-referenced so identifying any area of concern is quick and easy. For each section tested a concise report is provided detailing the findings. The results given are a unit of grip called Grip Number (GN) and SCRIM (by a mean of a well-established correlation).

Grip testing is suitable for trunk roads, side streets, junctions, pedestrian crossings, roundabouts, and most other areas that are trafficked (greater than 20 metres in length).

UKAS schedule available here.

*Please note that the Griptester does not provide a Polished Stone Value (PSV) and can only be used as a means to determine the grip values in situ. Please contact us for more info.