Linear and nonlinear modelling for capacity assessment of Saxon Street overbridge BFO/1B

This paper presents a summary of the assessment of Saxon Street overbridge (BFO/1B), located in Milton Keynes, as conducted by AtkinsRéalis to determine the bridge’s remaining live load capacity. Previous assessments indicated that the bridge was unable to support rail live loading, classifying it as ‘route availability zero’ (RA0) according to Guidance Note NR/GN/CIV/025 published by Network Rail (NR) in 2006. Currently, the bridge accommodates a single bi-directional track across its four-span arrangement. NR sought to explore the possibility of increasing the bridge’s assessed capacity to ensure its continued use. This paper delves into the assessment methodology, including the modelling, real-time testing and monitoring performed by East West Rail Alliance, to re-evaluate the bridge’s capacity and ensure its usability in the future.