The conversation around Nationally Significant Infrastructure Projects (NSIPs) has picked up pace recently, and for good reason says Glenigan.
With major schemes on the table and billions of pounds in potential contracts, main contractors are watching closely. Heathrow’s long-anticipated third runway has pushed NSIPs back into the spotlight, but it’s far from the only opportunity on the horizon.
For those working in the construction industry, NSIPs represent some of the most valuable and complex projects in the UK’s pipeline, offering scale, longevity, and strategic significance. Whether in transport, energy, or utilities, these schemes demand serious capability and provide substantial rewards.
Arguably, the most talked-about NSIP right now is the proposed third runway at Heathrow Airport (Glenigan ID: 18218583).
Image: Heathrow Airport
While the Development Consent Order (DCO) has yet to be submitted, it’s expected as early as Q4 2025. The £14 billion project includes a new runway northwest of the airport, a supporting airfield, terminal capacity, and major upgrades to surrounding infrastructure: roads, rivers, and the M25 among them.
The scale is unmatched. Once operational, the airport would increase from 475,000 to 740,000 air traffic movements annually. The potential for contractors is vast, but until formal plans are submitted, it’s a waiting game.
Elsewhere, momentum is building. In March 2025, the Lower Thames Crossing (Glenigan ID: 91161081) received development consent. At £10.2 billion, it will be the UK’s largest dual road tunnel, stretching 23km to connect Kent and Essex. It’s set to start on site in late 2026 and become operational by 2032—41 years after its initial proposal.
The project will be publicly and privately funded, with tolls introduced to help recover costs. It’s a landmark infrastructure scheme, offering long-term opportunities across a range of packages.
The pipeline continues to strengthen. In April 2025 alone, four additional projects received DCOs, bringing the total value of recent NSIPs to £16.74 billion. These include:
- Cambridgeshire Waste Water Treatment Works (£400 million, Glenigan ID: 20287986) – A significant upgrade for Anglian Water, featuring an integrated wastewater and sludge treatment facility, with tunnels, pumping stations, access roads, and renewable energy generation. Works are expected to begin in 2026.
- North Falls Offshore Wind Farm (£740 million, Glenigan ID: 20400991) – A joint venture between SSE Renewables and RWE. Layout changes were made following consultations, and the project will contribute to the Government’s offshore wind target of 50GW by 2030.
- Rampion 2 Offshore Wind Farm (£3 billion, Glenigan ID: 12402488) – Featuring 116 turbines and a generating capacity of 1,200MW, Rampion 2 is another key player in the transition to renewable energy.
- London Luton Airport Expansion (Glenigan ID: 21110220) – Granted amid some controversy, this scheme will support an increase in flights from 132,000 to 209,000 annually and boost passenger capacity from 18 million to 32 million by 2043.
Other major NSIPs are still moving through the system. Gatwick’s Northern Runway project (Glenigan ID: 03225160) is one to watch. A final decision is expected by 27 October 2025. If approved, it will raise capacity from 261,000 to 386,000 flights annually, with works due for completion by 2030 and an estimated cost of £2.2 billion.
Several other DCOs are pending with the Planning Inspectorate, with decisions due between late April and mid-July 2025.
Nationally Significant Infrastructure Projects are more than headlines—they’re high-value, high-impact developments shaping the UK’s future.
