Newsletter of The New Zealand Roadmarkers Federation Inc.
Roadmarking News www.nzrf.co.nz Edition 150 August 2021
Austroads Research Report AP-R633-20 Implications of Pavement Markings for Machine Vision NZRF Executive Committee members Chris Bradley and Dominic Elder will meet with Transport Minister Hon Michael Wood on the 17th August 2021. Among the matters discussed will be roadmarking requirements for Advanced Driver-Assistance Systems. While the path to level 5 fully autonomous vehicles is somewhat uncertain, a growing range of vehicles already available in the market offer automatedsteering functions enabled by Advanced DriverAssistance Systems (ADAS). Their performance depends on the vehicle’s technology and the environment where they are used. Currently an estimated 50% of all new vehicles have ADAS and that percentage is increasing rapidly.
The purpose of this report is to outline how longitudinal pavement markings affect automated steering functions and what if any the changes to current design and maintenance practices could be made to improve the support lane markings for advanced drivers assistance systems and in the future automated vehicles. Key findings; A minimum 3-to-1 contrast ratio (Qd) between longitudinal pavement markings and the surrounding substrate is generally supported by most machine-vision systems in most environmental conditions.
On-road trials found that machine-vision systems can read an 𝑅𝐿 contrast ratio for night-time visibility of between 5-to-1 and 10-to-1 between pavement markings and the surrounding substrate. Pavement ‘brightness’ can degrade machine-vision systems’ ability to detect longitudinal pavement markings in some conditions because it reduces contrast between the pavement marking and the substrate. Testing generally supports the current harmonised standard widths of 150 mm for edge lines and 100 mm for dashed lines. Dashed lines are more likely than solid lines to be difficult for machine-vision lane detection. Using clear continuity lines on both sides of the lane, with no extended gaps and a consistent lane width, is conducive to good lane detection, e.g., at exit ramps and intersections. Many of the recent harmonisation design standards meet or exceed machine-vision requirements. While many difficult-to-control factors can degrade the machine-vision-system’s ability to detect longitudinal pavement markings, improving maintenance standards and design principles can generate significant network-wide gains. A cost-benefit analysis found that when longitudinal pavement markings are improved, the potential discounted crash benefits exceed the discounted capital and maintenance costs by 3.28 benefits-to-costs ratio. Key recommendations in the project include; Road agencies support the standards in Harmonisation of Pavement Markings and National Pavement Marking Specification (Austroads, 2018a), particularly line width and Qd/𝑅𝐿 intervention levels. That road agencies improve design guidelines for continuity lines, exit ramps and intersections, to also consider the needs of
Published by: The New Zealand Roadmarkers Federation Inc. P O Box 13 605 Onehunga Auckland 1643 New Zealand Email: admin@nzrf.co.nz Roadmarking News in published by The NZ Roadmarkers Federation Inc. Opinions expressed in Roadmarking News do not necessarily reflect the views of the NZRF