New tool puts New Zealand on track for safer state highways

An improved testing system for road materials could make our state highways safer and more robust to withstand years of heavy traffic.

A new, modified “wheel tracker” device developed by University of Canterbury (UC) Associate Professor of Civil Engineering Mofreh Saleh is a more accurate way of testing the strength and durability of the materials used to construct new roads.

Professor Saleh specialises in Transportation Engineering and has been studying how asphalt and other highway materials behave under traffic loading.

He says it’s very important to be able to identify weak materials at the design phase to avoid them failing prematurely after they’ve been built.

This year, for example, the cost of repairing cracking in the Kāpiti Expressway and the Te Rapa and Ngaruawahia sections of the Waikato Expressway topped $80 million.

“These premature problems can be avoided with better and more rigorous testing methods to identify the performance of road materials,” Professor Saleh says. “This in turn will lead to long lasting and more stable infrastructure.

Poor quality road materials can lead to rutting in the road surface causing dips where water accumulates. Accidents can happen when drivers hit these uneven, wet areas at normal speed and lose control.

“Most of us drive every day on the roads and the last thing we want is to encounter hazards caused by poor materials that can lead to hydroplaning – losing traction in wet conditions – and increased risk of motor accidents,” he says.

“There’s also the cost and inconvenience caused by road maintenance and repairs having to be carried out more frequently. People end up spending more time stuck in traffic due to lane closures and we have to spend millions of dollars in taxpayer money to repair poorly constructed infrastructure.”

The modified wheel tracker that Professor Saleh has invented gives a more reliable testing result than the conventional testing system and it can be used for granular roading material as well as asphalt.

“The existing technology often gave inaccurate results – false negatives or false positives – so the material might seem safe but didn’t perform well when it was used in the field. The modified system we’ve come up with gives a more reliable, realistic result.”

It has recently been granted an international patent and is central to a new international standard adopted by the American Society for Testing and Materials (ASTM) which is used by many countries around the world, including New Zealand.

The new ASTM was approved in February this year and is now available to highway agencies and practitioners.

Professor Saleh is exploring options for commercialisation of the testing device and has been liaising with top United States universities such as the University of Texas and other research organisations in Australia such as the Australian Road Research Board (ARRB).

ENDS