This project was hugely ambitious, aiming to improve crowd flow within the building’s constricted corridors by installing a new staircase and forming an extended lower lobby, and to transform the theatre downstairs from a black-box studio into a fully equipped performance space. That the magnificent reality lived up to the vision is very much down to Joe Hacke.
The big challenge was not merely installing a transfer structure beneath the grade I-listed Paul Hamlyn Hall so that three supporting concrete piers could be broken out. It was also that the hall had to stay fully operational throughout as it was critical to maintaining public flows (and therefore ticket revenues) to the main auditorium.
Joe’s crucial contribution was to challenge a structural design that was risky to build. The only way to lift in the 19-tonne steel sections for the proposed transfer structure was to feed them through that iron and glass heritage facade by means of a difficult double-crane lift, then skid-steer them into position before dropping them at an angle through an enlarged cut-out in the reinforced concrete slab.
The engineer’s proposal was then to strand-jack the sections to preload them – without any knowledge of the actual load they needed to support. But with surveys suggesting that the fragile legacy structure they were to support would start showing signs of damage at 3mm of vertical movement and significant structural damage at 8mm, any damage would likely prove costly to fix and probably leave the hall unsafe for use until it had been repaired.
Instead, Joe championed a truss that could be manufactured and assembled in the building at ground level before being lifted into position. He introduced 12 new temporary columns, each incorporating a load cell and hydraulic flat jack, to take the load of the hall (and allow it to be measured precisely) before transferring it onto the new truss. It cost substantially more than the original design, but got the go-ahead after Joe’s persuasive explanation of the business case. Not a single pane of glass was cracked, total measured movement was 1mm downwards, and the hall remained operational at all times except during the final jacking process.
His other substantial contributions included dealing with the discovery that the theatre’s orchestra pit had frequently flooded over the years, corroding the acoustic bearings of the slab it sat on. His able and extensive resequencing allowed the bearings and slab to be replaced without completely blowing the programme.
He also made the complicated horseshoe arrangement for the theatre’s balcony fronts (differing radii and transition curves, with expected tolerances of zero) buildable by moving away from an overly challenging and costly American black walnut veneer. Instead, he had the fronts made from solid wood in narrow sections and hand-finished – 3,300 ‘hockey sticks’ individually made by computer-aided machines.