Dr Sauer & Partners has been assigned to assess the ground movement impact of the proposed BSCU tunnelling works on the existing LU (London Underground) & DLR (Docklands Light Railway) civil assets in the Bank-Monument station complex.
The assessment followed LU standards and focused on predicting damage to the structural linings. Typically the impact on the internal cladding and features are not specifically addressed in the assessment approach. However, LU and the ORR (Office of Rail Regulation) are becoming increasingly interested in the ground movement impact on finishes fixed to the linings, floor levels within the tunnels and the potential for increased water ingress where movements occur. The consequences of these hazards to the travelling public and operations must be mitigated; either in advance through removal/amendment of finishes or during construction in response to pre-defined inspection regimes focused on the predicted movements and asset criticality. Following discussions and meetings with the LU Engineers, Dr. Sauer & Partners carried out a qualitative assessment of the impact of the new works on the premises, for the assets that fall within the predicted 1mm settlement contour (Figure 1).
The output of the assessment has been used in joint risk reviews with Dragados and Bank LU Premises Manager. The feedback was positive and the LPE asked Dr. Sauer & Partners to present their approach at a meeting of the LU Premises Engineers as a way forward for future projects. The presentation focused on the approach used to assess the impact of ground movement on existing LU (London Underground) premises assets arising from construction of the proposed Bank Station Capacity Upgrade (BSCU) works.
On 28th April, Alexandra-Raluca Onisie-Moldovan presented to all LU Premises Engineers at 55 Broadway, discussing the DTTA (Deep Tube Tunnel Assessment) approach used at Bank station, focusing on the premises criteria such as impacts on finishes, water ingress and trip hazards. The types of proposed inspections were discussed as well as shown in Figure 2.
The presentation was well received and DSP, Dragados and LU’s work on BSCU (Bank Station Capacity Upgrade) was presented in a good light. It was much appreciated and is considered to be the first of many instances where this approach might be taken.
The presentation will potentially be used as a reference by other LU Premises Engineers to share the approach used by Dr. Sauer & Partners to tackle the impact on existing premises during construction of new works.