Initially, this structure was to be a Waldren Bridgette precast concrete modular bridge separate to the irrigation dam and flow regulator. Discussions between irrigation authority engineers and Rob Wallace resulted in a combined design whereby the precast concrete support and abutment walls also fulfilled the regulator functions.
Initially, this structure was to be a Waldren Bridgette precast concrete modular bridge separate to the irrigation dam and flow regulator. Discussions between irrigation authority engineers and Rob Wallace resulted in a combined design whereby the precast concrete support and abutment walls also fulfilled the regulator functions.
Accordingly, the precast concrete walls were designed to include all features necessary for both the bridge decks and the regulator gates. Stainless steel fixings for bottom hinged gates, motor drives, and channels for the stop boards were embedded in the concrete walls.
After the precast concrete super -structure was erected on concrete footings poured in-situ, the stainless steel hinges were suspended and carefully positioned between the walls. The concrete floor was then poured between the walls, embedding the hinges and the bottom half metre of the walls.
Rows of holes near the bottom of the walls enabled reinforcing bars to be extended across the full width of the structure to ensure structural continuity of the floor, crack control and hence prevent leakage.
