Hobart sits on a mix of dolerite bedrock, alluvial deposits, and weathered sedimentary layers. That variability directly affects how existing pavements behave under load. Our existing pavement evaluation in Hobart identifies weak subgrades, delaminated asphalt, and moisture-prone base courses before you mobilise a single machine. We combine falling weight deflectometer readings with calibrated calicatas exploratorias to expose hidden deterioration. The result is a clear rehab or overlay strategy that avoids costly guesswork. For projects near the Derwent estuary, where groundwater sits high, we also integrate ensayo CBR data to confirm soaked strength values. No two roads in Hobart are identical. Our approach treats every pavement as a unique asset with its own failure history and remaining life.
A pavement evaluation before overlay design can extend service life by 10 to 15 years in Hobart's wet temperate climate.
Methodology and scope
- Visual condition survey and distress mapping (cracking, rutting, potholes)
- Falling weight deflectometer deflections at 20 m intervals
- DCP penetration profiles down to 1.5 m depth
- Moisture content and field density by nuclear gauge
Local considerations
A contractor in Hobart once assumed an old asphalt road was sound because the surface looked intact. They milled 50 mm and laid a new wearing course. Within eighteen months reflective cracking appeared everywhere. The mistake was skipping a full existing pavement evaluation. The original base had turned to slurry under a thin seal. We have seen the same pattern on Sandy Bay Road and along the Tasman Highway. Without coring, DCP profiling, and moisture testing, you cannot know what hides beneath the seal. The cost of a proper evaluation is trivial compared to early failure of a $2 million overlay.
Applicable standards
AS 1726:2017 Geotechnical Site Investigations, Austroads Guide to Pavement Technology Part 2: Pavement Structural Design, AS 1289.6.1.1 Determination of the California Bearing Ratio of a soil
Associated technical services
Non-Destructive Testing (FWD & GPR)
We use a falling weight deflectometer to measure pavement deflection under a 40 kN impulse load. Ground-penetrating radar maps layer thickness and detects voids or moisture anomalies down to 2 m depth. Results are delivered as deflection basin plots and back-calculated moduli.
Destructive Coring & DCP Profiling
Cored samples recover asphalt and base material for lab testing (stiffness, binder content, gradation). Dynamic cone penetrometer profiles every 50 mm give a continuous strength log of unbound layers. We correlate DCP data with CBR values using the Kleyn-Savage relationship.
Laboratory Characterisation (CBR & Moisture Sensitivity)
Soaked and unsoaked CBR tests on recompacted samples determine design subgrade strength. Atterberg limits and linear shrinkage identify materials prone to moisture damage. We report the design CBR at the required traffic level per Austroads Part 2.
Typical parameters
Frequently asked questions
How deep does an existing pavement evaluation typically go?
We investigate to at least 1.5 m below pavement surface, or until we reach natural ground with consistent DCP readings. For airport pavements in Hobart, depth may extend to 2.5 m to cover the full structural section.
What is the difference between a visual condition survey and a full evaluation?
A visual survey records cracking, rutting, and surface defects. A full evaluation adds FWD deflection data, DCP strength profiles, laboratory CBR, and layer thickness verification. The latter quantifies remaining structural capacity and guides rehab design.
How long does an existing pavement evaluation in Hobart take?
For a typical 500 m road section, field work takes 1 to 2 days. Laboratory testing adds 5 to 7 working days. A complete report with FWD back-calculation and design recommendations is ready within 10 business days.
Do you evaluate both flexible and rigid pavements?
Yes. For flexible pavements we assess asphalt stiffness, base modulus, and subgrade CBR. For rigid pavements we measure joint condition, slab deflection, and concrete core compressive strength. Both follow the same FWD and coring protocols adapted to the layer structure.