Meet the academic detecting bridge defects using an instrumented train

Thirty thousand pounds granted to Dr Donya Hajializadeh as part of a Department for Transport funded programme delivered by Connected Places Catapult has helped the structures specialist to research the effectiveness of a novel method of monitoring rail bridges. If successful, the technology could be used to assess the condition of thousands of such crossings in the UK.

Donya received a Transport Research and Innovation Grant in 2021 to explore the potential application of an inspection system called INORAIL which aims to use trains travelling at operational speed to identify signs of damage and defects on railway bridges.

Donya is keen to explore how an instrumented train, and perhaps others carrying passengers in future years, could routinely be used to detect bridge defects such as scour, fatigue and steel corrosion.

She is currently working with Network Rail to assess how well the monitoring system can identify problems on a masonry bridge at an undisclosed location in the London region.

The INORAIL inspection system uses accelerometers that measure vibrations generated by a maintenance train as it crosses a bridge, to get a sense of the structure’s health. Defect ‘signatures’ are extracted from these vibration signals to detect damages that influence the structure’s behaviour.

Part of Donya’s research involves identifying how different bridge defects create different signatures depending on their size, the structural composition of a bridge and its age. Machine learning and a damage classification algorithm are used to interrogate the data.

“My hope is to create an efficient way of monitoring bridges, understand how structures are ageing and optimise maintenance regimes. In future it could lead to automated inspections, reducing health and safety risks of having inspection workforces at hazardous and hard to reach job sites.”

Dr Donya Hajializadeh, senior lecturer, University of Surrey

She adds that using a passing train to monitor bridge condition also removes the need to fix sensors to the structures themselves: a costly and time-consuming exercise that is bespoke to the instrumented bridge and is often carried out for a limited duration.

Trial on a model railway

Donya’s first demonstration of the technology was to the Guildford Model Engineering Society, based in Stoke Park in the town, which agreed to try out the system as a proof-of-concept trial on one of their model trains.

“After visiting the Model Engineering Society site on an open day, I was allowed to fit accelerometers to one of their trains to monitor the condition of one of their model overbridges,” Donya explains. “I added steel plates to different parts of the bridge and used the train to see if it could detect the changes I had made; and it worked!

“So I got in touch with Network Rail to share the results, and they agreed to try out the system for the measurements collected on a full-scale maintenance train.”

An ambition of Donya’s work is to transform indirect inspection systems and automate bridge damage identification; leading to early warnings, optimisation of maintenance regimes and reducing health and safety risks.

An outcome of the research may be to explore how existing bridges could have their life extended safely, and how learning from their defects and ageing profiles could be used in future adaptive designs.

“I am passionate about making the most of what already exists and putting the available data and resources to best use,” she says.

“We are looking at the data to offer wisdom to inform maintenance strategies. Better condition information will result in better planned and more timely maintenance interventions, that could avoid millions of pounds of untimely replacements. A consistent and automated inspection regime can also lead to the more efficient use of necessary detailed and special inspections, by focusing on critical zones.”

A lifelong love of bridges

Fascination with bridges began at an early age for Donya. “I used to collect photographs of structures from around the world such as Tower Bridge in London. But the Forth Rail Bridge in Scotland was always my favourite: pure engineering genius.”

“Bridges are a very tangible demonstration of physics in action; I couldn’t see myself pursuing any other career.”

Donya conducted her PhD at University College Dublin (UCD), focusing on road bridge traffic loading. Subsequently she worked for a consultancy firm as a research engineer alongside teaching at UCD.

She is a charted civil engineer and currently a Senior Lecturer and Director of Employability for Civil and Environmental Engineering programmes at the University of Surrey.

Donya says she is grateful to Connected Places Catapult for offering “help and mentoring throughout the research project”; as well as providing networking opportunities. These included arranging a meeting with former Transport Minister Karl McCartney MP, and introducing Donya to the Department for Transport’s Chief Scientific Adviser, Professor Sarah Sharples, who presented Donya and her team from Surrey University with the DfT Chief Scientific Adviser Innovative Solution Award at the end of last year.

Future ambitions

Moving forward, Donya hopes that her research can also lead to train-mounted monitoring systems being used to highlight concerns with the condition of small culverts beneath a railway.

She also points out that detecting problems early is important to help avoid unexpected track closures leading to passenger delays. She acknowledges that with a changing climate, differences in infrastructure ageing and defect profiles will be seen. Having a form of network-level monitoring therefore offers great promise in our understanding of the changing behaviours and trends, she adds.

For Donya, a successful outcome of her work would be the network-level use of monitoring systems that allow more effective monitoring and lead to optimised management of structures and more resilient networks.

“Bridges are essential components of our transport infrastructure and keeping them open makes a significant difference to people and local communities,” she adds. “The more certainty we can offer about the safety and resilience of structures, the more confident we can be in meeting future transport demands.”

Applications to take part in the Transport Research & Innovation Grants 2023 programme are open until 27 November.