Recommended changes to physical infrastructure practices to improve connected and automated vehicle support

Tuesday, 17 October 2023

Austroads has published a report that identified physical infrastructure practices that transport agencies could change to improve connected and automated vehicle support. The report addresses recommended changes to various design, placement, and maintenance aspects for line and pavement marking, electronic and non-electronic signs, and traffic signals.

“As the uptake of CAVs grows in Australia and New Zealand, there is a need for Austroads’ members to adopt minimum requirements for physical infrastructure and invest in practices that could improve CAV support,” said Joanne Vanselow, Austroads Future Vehicles and Technology Program’s Manager.

The report incorporates findings of previous Austroads publications focused on physical infrastructure requirements, complementary research into more recent publications and industry perspectives, and a review of Austroads member agency practices and standards.

Longitudinal line marking, such as edge lines and lane lines, are the most extensively discussed types of physical infrastructure to support the operation of various CAV capabilities. The review identified that high quality lines are likely to support CAV capabilities as well as human drivers; however, there is a lack of clarity as to true minimum criteria for CAVs for many attributes, for example, line width, minimum luminance value and minimum contrast levels.

The review of electronic sign needs identified three topics to address: lateral and vertical placement that should be in line with non-electronic sign practices, visual sign appearance considerations and LED flicker. Regarding flicker, there is broad industry support for the adoption of a minimum refresh rate of 200 Hz, at least for regulatory signs, for example, speed limit and turn restriction signs.

The identified needs for non-electronic signs included the need to harmonise practices with respect to using standard designs, lateral and vertical placements, and maintaining visibility and legibility levels.

The review of traffic signal needs found that given the differences in Austroads member agency signal lantern placement practices – that is, horizontal and vertical – when compared with Europe and Asia, it is likely that machine vision systems will need to be trained specifically for Australian and New Zealand roads. It was also identified that harmonised practice using a white bordered traffic signal may assist signal detection.

The report stresses that any changes made to physical infrastructure must consider the needs of human users. This is because the uptake of fully automated vehicles will take some years and human vehicle operators will continue to operate partially or highly automated vehicles.

“This report is a snapshot of the current knowledge related to physical infrastructure requirements based on evidence and industry opinions,” said Joanne. “As the CAV industry and vehicle capabilities evolve over time, so too will the actions requiring physical infrastructure changes to support them.”

Download Minimum Requirements for Traffic Signs, Traffic Signals and Line Markings