As extreme weather events grow more frequent and severe, Australia is recording a rising number of landslides, rockfalls and slope failures along its road network, and engineers say the country’s roads face growing risk from hazards that are largely invisible to those responsible for managing them.
Geoscience Australia identifies saturation of slope material from rainfall or seepage as a natural trigger for landslides.
Reports from the Bureau of Meteorology and CSIRO show the intensity of short-duration extreme rainfall has increased by at least 10 per cent in parts of the country in recent decades, with the sharpest rises recorded in the north.
The financial toll is mounting too.
Insurers paid out $2.19 billion in claims from declared extreme-weather events in the 2023-24 financial year, and Australia now ranks second in the world for weather-related losses per capita.
Despite this, most road authorities still assess slope danger the way they have for more than 15 years, with an engineer standing at road level, sketching and photographing terrain whose upper reaches are often out of sight.
Ian Thompson, director and geotechnical engineer at Civil Geotechnical Consultants (CGC), stated that the ground-level approach leaves too much guesswork.
“When you assess a slope from the road, you often can’t physically see the top of it, so you’re making educated guesses about what’s up there.”
The consequences of hazards going unseen were on display in Perth on September 8, 2026, when a car fell into a sinkhole that opened up in Canning Vale after a burst water main flooded the road overnight.
The sedan became stuck around 4 am after driving through floodwater on The Bridgeway, cutting off the water supply to about 10 nearby homes.
Water Corporation crews isolated the main within 30 minutes and began work to remove the vehicle and repair the pipe.
While the Canning Vale sinkhole was caused by failing underground infrastructure rather than a slope collapse, it illustrates a broader point engineers are making: road hazards that build up out of sight can fail suddenly, with little or no warning to drivers.
However, with the use of a drone, engineers can now fly a high-risk site in under two hours, detect hazards invisible from ground level, and build a model accurate to the centimetre, creating a baseline to track how risk changes over time.
The same method can be used to assess road corridors quickly after a cyclone or major storm, helping authorities reopen routes within the narrow windows allowed by disaster-recovery funding.
Work that once required three days with a geologist and a compass can now be done far faster and with greater precision, according to CGC, which says the resulting data gives governments and road owners a stronger basis for safety decisions.
CGC calls for high-precision aerial assessment to become standard practice on Australia’s highest-risk road corridors, not as a replacement for existing inspection methods but as an upgrade to them, so hazards are identified and measured before they fail rather than cleaned up afterwards.
Beyond slope monitoring, the same aerial survey technology is being applied to measuring earthworks volumes, tracking construction progress, assessing cuttings and embankments, and monitoring rockfall debris after a collapse so authorities can set exclusion zones, fencing or signage based on evidence rather than estimation.
It is also increasingly used for hard-to-reach structural inspections, including bridges.
As extreme weather events become more frequent and reach further south and inland than in the past, engineers argue that finding hazards before they fail, rather than after, will be central to keeping Australia’s roads safe.
