OLD OAK COMMON STATION (HS2)

Leca® was procured and selected as the chosen Lightweight Aggregate (LWA) specified as part of the construction of Old Oak Common (OOC) station in London.

Old Oak Common is being built on the site of former railways maintenance depots and is approximately 500 metres south of Willesden Junction. It will act as a major interchange connecting HS2 with the Elizabeth Line and Great Western Mainline services.

The project’s scale, depth and constrained urban setting present substantial geotechnical and structural challenges. Construction is taking place within a brownfield environment characterised by variable made ground, complex load paths and strict settlement criteria. In this context, Leca® LWA has been selected as part of the engineered ground solution due to its well-established performance characteristics and suitability for large-scale infrastructure works.

FACTS

Amount of material: 46,000m3 of LECA LWA (10-20mm)

Interesting Fact: Over 3000m3 of Leca® LWA was delivered and compacted in 2 weeks - providing optimised efficiency for the works program.

Delivery Method: Walking Floor

Main Contractor: Kilnbridge

Interview with Kilnbridge at HS2

Why was Leca® LWA Selected?

The Engineering Challenge

More than 46,000 m³ of Leca® LWA (10–20 mm grading) will be supplied to support formation works across the site. Its low bulk density compared with conventional fill materials reduces vertical and lateral loads on underlying soils and underlying and adjacent structures. This is particularly important where differential settlement must be controlled and where existing assets or newly constructed elements are sensitive to imposed loads.

Beyond weight reduction, Leca® LWA offers predictable compaction behaviour, high internal friction, and good drainage performance.

These properties help to:
•    Improve ground stability in areas of weak or variable subgrade
•    Reduce long-term consolidation settlement
•    Minimise lateral pressures on retaining and buried structures
•    Facilitate efficient installation within restricted working areas

More than 46,000 m³ of Leca® LWA (10–20 mm grading) will be supplied to support formation works across the site.

Its low bulk density compared with conventional fill materials reduces vertical and lateral loads on underlying soils and adjacent structures.

Construction is taking place within a brownfield environment characterised by variable made ground, complex load paths and strict settlement criteria.

The use of lightweight engineered fill contributes to both constructability and long-term performance, aligning with the project’s technical and commercial objectives.

The material’s consistency and ease of handling also support programme certainty, an important consideration on a project of this complexity, where sequencing, logistics and access are tightly managed.

Kilnbridge are a leading structural specialist company delivering the public realm, ancillary buildings and bridges package at Old Oak Common Station. They are working for the Tier 1 joint venture comprising Balfour Beatty, VINCI and SYSTRA. Their teams are operating within tight spatial constraints while coordinating deep excavation works, major structural elements and high-capacity rail infrastructure in a dense urban environment. The use of lightweight engineered fill contributes to both constructability and long-term performance, aligning with the project’s technical and commercial objectives.

We are proud that Leca® LWA will play a role in the delivery of Old Oak Common. As one of the UK’s most significant transport interchanges, it represents not only a major engineering achievement, but also a long-term investment in national connectivity and urban regeneration.