A Deflectograph is a survey vehicle used to produce data for the assessment of pavement strength. It is a lorry based system, with a pair of wheels at the front and a pair of double wheels at the rear. At the start of testing a pair of deflection beams are lowered onto the road surface. The Deflectograph then moves forward, so that the double wheels on the rear of the vehicle straddle the two beams. This causes the pavement to deflect (due to the vehicle’s weight) which is measured in the two beams. Once the rear wheels have reached the end of the beams, the beams are brought forward and the process is repeated again. This results in deflection measurements taken at approximately 4m intervals. These machines survey at 2.5km/h and are further discussed in HD29 (DMRB Volume 7 Section 3).

The Accreditation and QA requirements for these devices are given in the Accreditation and QA specification .

Accreditation_and_QA_of_Deflectograph_devices Issue 2.0 July 2016.pdf

If you are looking for a contractor to carry out Deflectograph surveys compliant with HD29 on your behalf, you may wish to check the list of Deflectograph Survey devices below. On this page you can also find the latest accreditation certificates. Certificates from previous years can be found here

Certificate Reg plate Operating Company
2017_DFG_M02_L697_BKR L697 BKR PTS
2017_DFG_M03_B180_FBL B180 FBL TRL
2017_DFG_M05_D962 JRU D962 JRU WDM Ltd
2017_DFG_M08_BYW_80V BYW 80V WDM Ltd
2017_DFG_M09_VGV_182X VGV 182X WDM Ltd
2017_DFG_M10_F569_JBB F569 JBB WDM Ltd
2017_DFG_M12_EOU_230W EOU 230W WDM Ltd
2017_DFG_M14_B195_CFW B195 CFW Lincolnshire County Council
2017_DFG_M15_ACZ_3268 ACZ 3268 DoE Northern Ireland
2017_DFG_M16_B880_XOU B880 XOU WDM Ltd