The HWD (Heavy Weight Deflectometer, Figure 4) operates on the same principle as the FWD, but has the ability to exert greater pressure on the pavement under test (up to 320 kN). Therefore, it is mainly used on airport pavements, which have a much thicker structure than road pavements

HWD rys 4

Fig. 4 Heavy Weight Deflectometer (property of IBDiM)


The results of FWD and HWD measurements can be used not only at the project level, but also at the road and street network level. At the network level, the results obtained can be used, among others, to build a data bank of road load bearing capacity, which is helpful in properly setting budgets, allocating funds, typing sections for repair or reconstruction, and prioritizing activities on the road network.

The main task of deflection meters is to assess the load bearing capacity of the pavement, but the results of the measurements can also be used for other purposes, such as:

  • determination of the stiffness modulus of individual layers of the structure,

  • dimensioning of reinforcements using the deflection method,

  • evaluation of support conditions of rigid (concrete) layers,

  • evaluation of the interaction of the plates in the “reflected” crack.


Testing with FWD and HWD is falls within the scope of accreditation of the Testing Laboratory No. AB 426, issued by the Polish Accreditation Centre.