Deflectograph

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.

accreditation_and_qa_of_deflectograph_devices_issue_3.1_jun_2020.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. 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.