Latest road maintenance assessment technology to save time and money for asset managers.
by Dan Stojanovich
It takes a very well trained and experienced human eye to pick an imperfection in a road surface well before it becomes a mess of expensive-to-fix potholes – but doing so at up to 80km/h, hour after hour, day after day? Inspecting, testing and documenting all the way?
The TSD can.
Installed in a semi-trailer, a single Traffic Speed Deflectometer unit is expected to cover 20,000km in Queensland, 21,000km in
NSW and 12,000km in New Zealand in its first 12 months of operation under a five-year agreement signed with ARRB Group (formerly the Australian Road Research Board).
According to ARRB, “it is estimated the TSD will deliver significant savings to Australia and NZ’s combined $18 billion annual road budget.”
Greenwood Engineering in Denmark built the TSD to ARRB specifications, with additional surveying technology integrated within the data collection system designed by ARRB. The basic TSD concept is to measure the velocity of deflection rather than displacement. As the velocity of deflection is the derivative of displacement, it is possible to calculate the displacement.
TSD uses special Doppler technology patented by Greenwood to measure pavement deflection while travelling at up to 80km/h, providing continuous pavement deflection profiles from which bearing capacity indices can be derived and pavement fatigue/residual life estimated. The high accuracy and resolution makes TSD perfect to pinpoint locations needing repair.
The TSD also incorporates a sophisticated arrangement of high-tech lasers, cameras, a load-sensing mechanism and complex software to observe, measure and record key roadway data such as pavement condition and deflection at speed and under load. Six Doppler lasers placed at strategic points along the chassis of the semi-trailer measure deflection as the truck travels along.
However, the TSD is more than a one trick pony.
It also simultaneously measures the strength, roughness, rutting, texture, cracking extents and imagery of the road, giving engineers the most complete snapshot of road conditions that has ever been available – the kind of data that provides a reliable indicator and predictor of road surface integrity and longevity.
The alternative, long-used Falling Weight Deflectometer (FWD) conducts a single test at just one location at any one time, so it could take years to cover a whole road network – as well as generating traffic interruptions and safety risks. The TSD is a genuine game changer.
Hawkeye Automatic Crack Detection (ACD), digital imaging and laser profiling technology have also been fitted to the TSD. Hawkeye ACD consists of two high-performance 3D laser units that capture and analyse the cracking characteristics of the road surface.
There are only eight TSDs in the world (in Denmark, UK, Italy, South Africa, Poland and China), and the adaptations made to the model owned by ARRB makes the Australasian TSD one of a kind.
“Before [roads] break down you can resurface them, but once you get potholes you have to rip up the road and start again,” said Garry Warren, General Manager ARRB Systems. The TSD can save considerable time and money as it speeds along generating some 560 megabytes of data per kilometre.