The viaduct over the Malahide estuary re-opened to rail traffic just 12 weeks after its collapse.
Summary
Roughan & O’Donovan undertook a peer review of all design proposals prepared by Irish Rail directly and the geotechnical and hydraulic designs carried out by other independent consultants.
Solution
Geotechnical designs
Our independent check and peer review included:
- determination of the scour resistance of the stone fill weir
- seepage analysis/piping resistance of the stone fill weir foundation
- stability analysis including construction conditions, and permanent conditions
- settlement analysis of the modified stone fill weir and causeway
Hydraulic designs
Our sub-consultant, Hydro Environmental Ltd, undertook an examination/determination of the hydrological and hydraulic conditions at Broadmeadow Estuary prior to collapse.
Structural/bridge analysis
We carried out an examination of the new substructure and superstructure design, providing advice, methodology and personnel for the inspection and testing of the post-tensioned beams, on and off-site.
This enabled us to determine a correlation between the observed condition of the post-tensioned beams off-site to the condition of the remaining bridge beams on-site.
Probabilistic assessment
We undertook a probabilistic assessment of the complete superstructure using deterioration models to:
- determine its structural reliability (in accordance with the Eurocodes)
- predict its remaining life, with and without major interventions in the future
Challenge
Broadmeadow Estuary is protected by extensive environmental legislation and, as such, works in the area needed to adhere to strict environmental conservation requirements.
Services provided:
- Environmental engineering consultancy
- Civil engineering design
- Structural engineering design
- Bridge engineering design
- Risk-based asset management
