Reconstruction of two 100m long bridges which spanned the North & East London Line directly outside Highbury & Islington Station. The bridges effectively create a pair of tunnels which severely access to the underside of the bridge decks.
Andun were involved in providing demolition engineering and temporary works design support for the Highbury Corner bridge replacement project from the initial tender stage, until project completion in March 2018.
The works were undertaken in five phases to ensure that services across the bridge could be maintained.
Phase 1 – demolition of a precast post office structure and the removal of a series of masonry vaults adjacent to the South side of the bridge.
Phase 2 – demolition and reconstruction of a short section of deck above the ELL, directly outside the station. Access was very tight and required careful planning. The section of structure being removed consisted of masonry jack arches between cast iron beams. A carefully controlled sequence was therefore required to prevent the cast iron beams being damaged.
A crash deck was constructed in the tunnels below the section of bridge being removed. The deck plays three roles:
- Provides propping to the abutments;
- To make clearing up rubble simpler and faster, whilst providing suitable protection to the railway and OLE.
- Provide safe access for the rebuild of the deck, including abutment trimming and installation of the new bank seats.
This was followed by Phase 3, which was similar in nature to phase 2.
Phase 4 was the removal of a series of masonry jack arches within the central pier between the NLL & ELL.
These arches ran perpendicular to the bridges under the highway, which meant a clever propping sequence had to be devised to maintain the highways whilst allowing the removal of the section of arches that needed to be removed.
During Phase 5 the remainder of the bridge was replaced during a week-long possession at Christmas 2017. The works were carefully planned to ensure that the tight possession programme could be met.
Our scope of works included:
- Demolition of post office;
- Hoardings and temporary highway restraints;
- Bridge demolition sequencing;
- Assessment of existing structure for plant loads
- Abutment stability;
- Service support;
- Vault demolition;
- Temporary bridges;
- Edge protection;
- Numerous crane positions;
- Concrete pump positions;
- Construction sequencing;
- Track protection;
- Shutter design;
- Bridge jacking;
- Vibration monitoring predictions
- Inspections of structures;
- Various temporary support schemes;
- Vehicle barriers;
- Assessment of permanent works in temporary condition;
- Network Rail F002 & F003 submissions
- CRE (D) role
- Site supervision of demolition works