Since 2009, Geo-Design have worked as Specialist Advisors to the Clifton Suspension Bridge Trust to assess the existing stability state of the slopes which support the bridge abutments and to guide the long term slope maintenance requirements.
The Clifton Suspension Trust is commissioned to preserve the Bridge in perpetuity for use by the public. In the knowledge that there is a long history of instability in the rock slopes along the Clifton Gorge, The Trust appointed Geo-Design as Specialist Advisors to assess the stability state and maintenance requirements of the slopes which support the bridge abutments.
Geo-Design’s engineering geologists undertook an initial stability assessment of the 150 year old bridge foundations, using engineering geological models developed from review of published data (recent and historical), detailed mapping of the slopes and a deep drilling campaign. The geological models were digitised and used in state-of-the-art UDEC computer analyses to assess the stability state of the foundations and slopes applying a number of difference bridge loading scenarios.
UDEC analysis of slope under bridge loading
Inspection and capacity evaluation of the bridge ‘chain’ anchorages has also been completed.
Over time the geological models have been updated and verified using geological mapping techniques such as laser scans (LiDAR) and photogrammetric surveys to collect accurate point cloud data. These data have been used to verify and refine the original 2D geological models.
3D point cloud models of Clifton Suspension Bridge – Southwest Slope
Most recently, as part of Geo-Design’s ongoing role at the bridge, the team have been on site to supervise slope maintenance activities on the Clifton Southwest slope. The project comprised installation of rock bolts and dentition (infilling) of open joints in the rock to preserve the condition of the slope. The works were designed, tendered and supervised by Geo-Design working with COWI.
Rope access slope survey of Bridge Abutment