Monitoring of the Queensferry Crossing, Scotland

Abstract

The Queensferry Crossing opened in 2017 to enhance the resilience for road vehicles crossing the Firth of Forth outside Edinburgh, Scotland. The M90 carriageway consists of two lanes of traffic in each direction and hard shoulders. The three-tower, cable-stayed structure extends for 2.7 km, including approach viaducts. Structural health monitoring was specified by the employer in the construction works including 2184 physical sensors, which is believed to be the world's largest bridge monitoring system. This paper describes the monitoring and its uses thus far. A load test was conducted in 2020, comparing the sensor data favourably to the design. The monitoring is now integral to the operation of the bridge for measurement of structural performance and the management of the route. Automated reports give analysis of fixed periods of time and further detail for specific triggered events in occurrences of high load, abnormal load movements and extreme weather. The user interface includes a threshold alert system informing of the need for specific inspection and maintenance regimes. Route management in winter and extreme weather response is enhanced with the inclusion of sensor data. Monitoring data are also being used for research at various universities, each of which is described in brief.