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That was the question at the heart of several rewarding weeks for the TRL team as we delivered the first PAS 2161 correlation trial across three sites in Nottinghamshire, Cheshire and Lincolnshire.
The trial formed part of TRL’s work as the Department for Transport’s PAS 2161 approvals auditor. However, behind the standard, the technology and the data was a very human exercise, one that relied on the concentration, consistency and professional judgement of the engineers who took part.
Seeing the road through an engineer’s eyes
During the trial, participating engineers were driven along carefully selected routes and asked to assess the condition of the carriageway continuously as it changed beneath them.It may sound straightforward but maintaining that level of focus while consistently identifying and recording changes in pavement condition is no small task.
Their assessments will provide an independent benchmark against which data from road condition monitoring systems can be compared. This will help demonstrate how closely automated technologies correspond with the judgement of trained and experienced highway professionals.
Delivering the exercise across three locations also allowed us to assess a variety of roads and pavement conditions, contributing to a robust and impartial process.Why does this comparison matter?
Local highway authorities depend on reliable information to understand the condition of their road networks, decide where maintenance is most urgently needed and make the case for long-term investment.
New road condition monitoring technologies offer exciting opportunities to collect this information more efficiently. However, authorities need to be confident that the data produced is accurate, consistent and comparable, even when different technologies are being used in different parts of the country.
PAS 2161 provides a common framework for collecting and reporting road condition data. From 2026 onwards, local highway authorities will be required to submit classified road condition data to the Department for Transport in the PAS 2161 format using approved technologies.
As the Department for Transport’s PAS 2161 approvals auditor, TRL is responsible for independently assessing those technologies and verifying that they can deliver data in line with the standard.
The correlation trial is an important part of that process, connecting the expertise of highway engineers with the capabilities of emerging monitoring systems.
A successful trial depends on people
Although the trial will ultimately support the assessment of technology, its success depended on the people involved.
We are incredibly grateful to every engineer who gave up their time to participate and brought their knowledge, concentration and enthusiasm to the exercise.
We would also like to recognise the TRL drivers and technical team, whose careful preparation and professionalism helped the trials run smoothly and safely at every site.The feedback we received from the participating engineers reflected both the quality of the experience and the value they placed on contributing to the future of road condition monitoring.
One participant told us:
“Everything in the trial was very well planned, and the training at the start was very focused and well delivered. The risk assessment was detailed and easy to follow. I used it to inform my own safe system of work, and it gave me several ideas about how I might conduct risk assessments in the future.”
Another said:
“The pre-meeting on the day was very good, and the requirements were made clear. I found the experience very rewarding in terms of contributing to the correlation work for PAS 2161 technologies. The drive-throughs were undertaken by an excellent TRL driver, and the work was enjoyable and very interesting.”
Feedback like this matters. It shows that the trial did more than generate data: it gave highway professionals an opportunity to contribute directly to how new road monitoring technologies will be assessed and used.
Turning reliable data into better decisions
Completing the first correlation trial is an important milestone, but it is one part of a wider programme.
TRL will continue working with the Department for Transport, local highway authorities and technology providers throughout the PAS 2161 approvals process. Technologies will also go through an ongoing two-year reapproval cycle to ensure that they continue to meet the required standard.
The ultimate aim is straightforward: to give local highway authorities greater confidence in the information they use to manage their networks.
More consistent and comparable data can help authorities identify priorities, plan maintenance and demonstrate where investment will deliver the greatest benefit. Over time, this should support more efficient management of England’s roads and better outcomes for everyone who uses them.
For now, we are pleased to have completed a successful first trial, and thankful to everyone in Nottinghamshire, Cheshire and Lincolnshire who helped make it possible.
On to the next stage
Technology providers interested in achieving PAS 2161 approval, and local highway authorities seeking further information about the standard or approvals process, can contact us on RCMtrial@trl.co.uk to find out more.
