A ‘dip’ into DipStik Technology!
As well as the key assets (highway, footways, public rights of way and cycleways) that comprise our network, Buckinghamshire Highways maintains a variety of assets that support the 3,186km of carriageway, including almost 30,000 streetlights.
Structural Testing is an assessment of a street lighting column/post, above and below ground to check for any risk of structural collapse and is carried out to ensure the street lighting assets are of good structural integrity. The Structural Testing Programme is carried out on a six-year rolling schedule and our teams are currently in year five of the programme (2025-26).
This year, the Structural Testing Programme is being carried out across the six wards within the Aylesbury area of the county. A total number of 5,608 assets are to be tested.
Structural Testing is carried out using Dipstik Technology, a method which assesses the health of metal street lighting columns from the inside out, without digging or damaging anything. It’s essentially a health scan for metal streetlight columns, which can rust and weaken underground—right where we can’t see them. Over time, this hidden corrosion can lead to dangerous collapses.
Dipstik Technology being used to assess a streetlight column
As a very basic explanation, Dipstik Technology works by inserting a small probe into the base of the streetlight column. The probe uses magnetic waves (called eddy currents) to scan the metal, detecting loss of wall thickness, corrosion, and other cracks or structural weaknesses—even below ground level.
Watch the video below about how Dipstik Technology works.
The 2025-26 Structural Testing programme commenced on the 27 May 2025 and is due to be completed on 31 July 2025. Use of Dipstik Technology has a range of benefits, which include;
- A non-invasive approach meaning there’s no need to dig up the column base
- Fast and efficient delivery meaning it’s ideal for large-scale testing across urban areas
- Detects issues that visual inspections or surface testing may miss
In addition to this, Buckinghamshire Highways also carry out an electrical testing programme in tandem with the structural testing. This combined approach offers better value for money.
Once the testing programme is complete, our Street Lighting team gathers all the structural data and uses this to plan a programme of replacement street lighting column and post installations. You can read more about this programme in the Highways Highlight blog: Relight my shire! | Buckinghamshire Council
The structural data for each column is categorised using a scoring system which is based upon defects, corrosion fatigue, height and road speed and each asset is summarised with an overall RAG status, as below.
Red – Asset has significant structural defects.
Amber- Asset has single or several structural defects.
Green – Asset has no structural defects.
Examples of significant structural defects (Red category)