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 CS 229 (part of the Design Manual for Roads and Bridges or DMRB).

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



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. In this table machines are referred to as having met criteria if they have met the mandatory criteria as defined in the Accreditation and QA specification for these devices. Some Network Authorities may also require a specific level of performance in some or all of the additional tests. Please see the certificates for more detail on the performance of these devices in these additional tests.

Certificates from previous years can be found here

ID       Reg plate           Operating company         Met criteria             Certificate
02 L697 BKR PTS Yes  
03 B180 FBL TRL Yes 2020_dfg_m03_b180_fbl_.pdf
05 D962 JRU WDM Ltd Yes 2020_dfg_m05_d962_jru_.pdf
08 BYW 80V WDM Ltd Yes 2020_dfg_m08_byw_80v_.pdf
09 VGV 182X WDM Ltd Yes 2020_dfg_m09_vgv_182x_.pdf
10 F569 JBB WDM Ltd Yes 2020_dfg_m10_f569_jbb_.pdf
12 EOU 230W WDM Ltd Yes 2020_dfg_m12_eou_230w_.pdf
14 B195 CFW Lincolnshire CC Yes 2020_dfg_m14_b195_cfw_.pdf
15 ACZ 3268 DoE Northern Ireland Yes 2020_dfg_m15_acz_3268_.pdf
16 B880 XOU WDM Ltd Yes 2020_dfg_m16_b880_xou_.pdf