Cranfield Road Bridge & Bridleway Bridge

Client: Morgan Sindall
Location: Cranfield Road Bridge & Bridleway Bridge
Sector: Infrastructure
Service: Vibration Monitoring

Central Bedfordshire Council undertook an ambitious project to upgrade the A421 road by installing a dual carriageway from the Eagle Farm roundabout down to Junction 13 of the M1. This particular stretch of the A421 is used by 30,000 vehicles a day. After the road is upgraded it will strengthen local infrastructure, take traffic away from local parishes and benefit local businesses.


Stroma was asked to provide expertise to monitor vibration levels in Peak Particle Velocity (PPV) over three different axes, at both Cranfield Road Bridge and the Bridleway Bridge which traverse the M1 and A421. Vibration monitoring was needed to help protect parts of the bridges which would remain standing after the demolition process.

During a 42-week project, Stroma Built Environment provided vibration monitoring services as part of a wider £28.5m project carried out by Morgan Sindall in conjunction with Central Bedfordshire Council. The project involved upgrading a three kilometer stretch of the A421 into a dual carriageway to more effectively link Junction 13 of the M1 motorway with Milton Keynes.

Stroma monitored activity around demolishing elements of the two bridges, to subsequently widen and extend them. Stroma’s monitoring helped protect the structural asset, by informing our client of the vibration impacts of the work being carried out in real time. Importantly, vibration monitoring of this type is becoming mandatory as a result of the increasing level of sophistication of sensors producing a high level of detail during the monitoring process. As the process continued, Stroma was able to report in detail when an exceedance occurred. We were able to analyse each event in depth to better understand the nature of the exceedances, which in turn better informed our client.

“Stroma’s professional approach and real-time data reporting across both bridge sites enabled us to monitor vibrations - to protect sensitive receptors and structural assets during the 42-week project. We knew exactly what kind of impact our operations produced in terms of vibrations as it happened.”

Steve Martin, Site Agent – Highways Morgan Sindall