Advances in technology now make it possible to collect information about the condition of our roads at speed. The Traffic Speed Deflectometer (TSD) is equipped with doppler lasers, GPS, cameras, temperature probes and 3D sensors; all working together on a heavy vehicle to collect vast amounts of information whilst travelling at a highway speed of 80 km/h. Information collected replaces tests that required low speed or stationary vehicles. WARRIP conducted a trial to validate this test collection method and equipment, finding that this TSD method delivered useful information. Cracking, deflection, roughness and rutting data was processed and further data collection projects using the TSD are currently underway.
Main Roads assessed the repeatability of the traffic speed deflectometer (TSD) across numerous sites in WA. This validation exercise aims to ensure Main Roads can optimise the TSD data collection.
The TSD was developed by Greenwood Engineering, Denmark, in the early to mid-2000s, to assess the functional and structural performance of a road network at normal highway speeds (80 km/h) (Rasmussen, Krarup & Hildebrand 2002). Appropriate use of the TSD may provide significant benefits to the Main Roads data collection program, ensuring Main Roads are able to make best use of the investment in their data collection program.
- Reviewing data collection programs undertaken by New Zealand and other Australia state road agencies
- Reviewing how collected data may be used
- Data collection with the TSD and post- processing of the data in Western Australia
- Providing recommendations to maximise the use of TSD data collected to enhance pavement asset management operations and deliver a sustainable framework for long-term strategic planning.
Calibration of TSD
Prior to the trial, the equipment was calibrated against a ‘ground truth’ data set that is traceable back to national standards. Local calibration were also performed to ensure consistency of measurement.
For a longer-term contract, a benchmarking site would need to be established locally following consultation with Main Roads. A calibration would then be performed every six weeks to ensure that any issues are identified as early as possible and that the impact on any data collected in the interim is minimised.
TSD data use
- identify weak pavement areas
- estimate remaining pavement life and pavement layer thickness
- develop future maintenance programs
- pavement rehabilitation design.
TSD Data Collection in WA
The TSD surveyed approximately 900 km of Main Roads’ road network (TSD 900) between 7 November and 13 November 2016. The data was post-processed using the Hawkeye Toolkit, providing linear geo-referencing information, event tagging and road section identification.
Rasmussen, S, Krarup, J & Hildebrand, G 2002, ‘Non-contact deflection measurement at high speed’, in AG Correria & FEF Branco (eds), Proceedings of the 6th international conference on the bearing capacity of roads, railways and airfields, Lisbon, Portugal, pp. 53-60.