What Happened / Impact?
At the end of the 2016/2017 premier league football season, the second phase of the White Hart Lane demolition commenced as Tottenham Hotspur moved stadiums to Wembley.
The South stand primary truss was the final truss to be removed and measured 110m long, 8m high and 3.5m wide, with an estimated weight of 250Te.
Initially, the intent was to undertake a cut and drop; however, a review confirmed this was unfeasible due to truss geometry and project schedule. An onsite review confirmed the feasibility of doing a pull down, however the West end sat on simple pot bearings supported on the east legs of the support tower; this created the possibility that the truss may sit into the tower and get trapped with the potential to overturn the support tower causing damage.
A solution was devised, which required pulling the primary truss at various angles and timings. The plan was to release the east end from the gallows truss and immediately it was free to give a quick tug on the west end to ensure a clear drop from the west tower. A weight was attached to the gallows bracket on a steel wire. This system acted as a dashpot piston to slow the release of the strain energy from the gallows truss. A 3D model was generated and a series of drawings prepared to demonstrate planned arrangements.
Whilst there were slight delays in getting all the preparation works completed successfully, the pull down occurred in front of a crowd of approximately 2000 people and was undertaken flawlessly. See video provided by Andun: http://See video provided by Andun: https://andun.co.uk/case_studies/white-hart-lane-phase-2/
Immediate Learnings / Recommendations
- The importance of undertaking an onsite assessment of hazards cannot be understated.
- Benefits of utilising 3D models and drawings to illustrate proposed methodologies.
- Pre-planning allowed for identification of the best practicable means for demolition and allowed for the scheduling of works to accommodate public interest.