Spring Street Car Park strengthening

We completed a challenging seismic strengthening project at Tauranga’s Spring Street parking building, taking it from 25% to 67% of the New Building Standard (NBS). We used a combination of methods to strengthen the structure, including:

• Adding reinforcing steel to concrete block walls and applying shotcrete to further strengthen them
• Installing 130 tonnes of structural steel through the centre wall and beams, bolted together vertically and horizontally
• Reinforcing the connection between the perimeter beams and the walls with bolted splice joints
• Strengthening the Dycore flooring system by packing it with high-strength grout at structural steel locations
• Bolting steel bracing under the ceiling, walls and beams and packing them with grout

The steel bracing element alone involved drilling around 8,000 holes, averaging 20mm in diameter and 600mm in length – approximately 4.8kms of percussion drilling. We worked with the structural engineers and local engineering fabricators to design a custom drilling rig, a 3-tonne tracked excavator with an adjustable frame holding two hammer drills. This allowed a single worker to drill the holes from the excavator, eliminating or significantly minimising the health & safety risks and considerably expediting the work.
This innovative solution took out the Health category at the 2023 NZ Workplace Health and Safety Awards.

The car park stayed open throughout the 13-month project. We carefully managed our work areas, cordoning them off from the public with road cones and clear signage. We also used noise blankets and dustless drill bits plus extraction to minimise disruption.