What is it?

The Falling Weight Deflectometer (FWD) is a non-destructive technique used to assess the structural capacity and performance of pavements by measuring their deflection under a load.

The FWD provides an accurate assessment on the structural condition of highways, local roads, car parks and airport runways and can also be applied to subgrades and sub-bases during construction. FWD is also used to identify voids underneath the surface or how two surfaces, typically concrete slabs are in contact with each other. Another benefit of the FWD is that it is a non-destructive test.

Benefits and Versatility

  • Pavement rehabilitation and overlay
  • Assess the remaining life of the pavement
  • Joint Sealing evaluation
  • Void detention
  • Conduct ‘whole of life’ costs and economic cost benefit analysis of alternate pavement design
  • Report layer moduli (stiffness), deflection, curvature and sub-grade CBR
  • Provide Quality Assurance assessment of recent works to ensure that they meet design life criteria
  • Assess the impact of increasing road volumes, traffic types or load capacities on the life and quality of the pavement
Falling Weight Deflectometer Out Working

Why do it?

Falling Weight Deflectometer (FWD) is a critical method of assessing the structural condition of a pavement. FWD data is primarily used to estimate pavement structural capacity for overlay design and to determine if a pavement is being overloaded. FWD is a trailer mounted non-destructive testing device. Changes in pavement construction can be identified when the measured deflections are plotted according to the distance along the site, which allows the development of maintenance recommendation to be based on localised pavement conditions.

Why PTS?

PTS operate five FWD machines all compliant with DMRB: Pavement CS 229 Data for pavement assessment (formerly HD 29/08). PTS can undertake assessment of asphalt and concrete pavements and provide standard deflection testing along with load transfer and void intercept testing. We have the technical capability and experience to undertake back analysis of the data with our in-house pavement engineers. Back analysis is best supported with Ground Penetrating Radar (GPR) data and coring, these surveys are also delivered by PTS site engineers.


Additional Services

PTS current customers include Highways England, Highway Authorities, Contractors, DBFO Companies and Airport operators in which we utilise innovative, fully compliant survey methods to deliver the following surveys; coring, coring for tar testing, GPR, SCRIM®, Deflectograph, FWD, GripTester, automated visual condition surveys, safety barrier inspections, Retro-reflectivity of road markings and traffic signs, construction materials testing and certification.