Transpower identified a need to strengthen parts of the transmission network through its Tactical Thermal Upgrade programme. Northpower was engaged to deliver the largest and most complex grillage foundation project undertaken by our transmission lines team to date, supporting long-term network resilience in challenging terrain.

This project involves constructing reinforced concrete foundations across remote and difficult-to-access sites, requiring careful planning, specialist capability and close co-ordination between project, planning and field crews.

Delivered as part of Transpower’s contestable works programme, the project involves multiple specialist partners, including concrete, access and aviation contractors. With 93 foundations planned, the concrete over grillage component represents the largest and most commercially significant part of the works.

Transmission foundation construction requires specialised technical skills, disciplined sequencing and adaptability in the field. For this project, Northpower crews operated a 12-days-on, 2-days-off roster, working from multiple temporary locations to maintain productivity.

Each foundation followed a consistent cycle of work:

• establishing site access and work areas
• excavation and preparation of tower legs, including cleaning and painting
• staged concrete pours, typically two legs per day
• reinstatement and grass seeding to return sites to a good standard.

Access roads were formed and reinstated progressively, ensuring plant and materials could reach each location safely and efficiently. In the most constrained sites, concrete was flown in by helicopter and pumped into position — an approach that enabled work to continue in areas otherwise inaccessible by conventional means.

Progress to date includes completion of 39 of the 93 planned structures and the placement of 817.2 cubic metres of ready-mix concrete, maintaining programme momentum despite complex terrain and logistics.

Safety and wellbeing remained central throughout delivery. Remote working, heavy machinery and stored mechanical energy risks were managed through detailed planning, robust daily checks and disciplined execution in the field.

In March, the project achieved a 100% score in Transpower’s Machinery, Plant and Stored Mechanical Energy Critical Controls Assessment, reflecting strong alignment between planning, supervision and on-site practice. This outcome was supported by experienced site leadership, clear communication and a shared commitment to maintaining high standards across all crews.

Site operations were supported by a fully functional mobile site office, enabling teams to operate effectively wherever the project required.