Autoripage® installation of 8,330‑tonne underpass structure across the M27
Client: Hampshire County Council
Contractor: VolkerFitzpatrick
Location: M27 Junction 10, Fareham, Hampshire, United Kingdom
Project milestone: Box slide successfully completed – Dec 2025
Project background
The M27 Junction 10 Improvement Scheme is one of Hampshire’s most ambitious highway infrastructure upgrades, commissioned by Hampshire County Council in partnership with National Highways. The project is critical to unlocking the development of the Welborne Garden Village, a new community comprising up to 6,000 homes near Fareham.
To support the long-term expansion and improve regional mobility, the scheme transforms the existing interchange into a fully operational “all‑moves” junction, significantly upgrading access between the M27 and the surrounding strategic road network.
Key components of the improvement scheme include:
- Construction of a new motorway underpass west of the existing Junction 10.
- Installation of three new slip roads and a new dual carriageway linking the slip roads to the local road network.
- Enhanced walking, cycling, and horse ride facilities.
These upgrades are designed to create a free‑flowing link, improve local traffic flow, provide additional network capacity, and support the region’s long‑term housing and economic growth objectives.
The box slide structure
A defining engineering feature of the scheme is the installation of a massive, pre‑constructed reinforced‑concrete underpass, delivered through a precision box slide operation completed over the 2025 Christmas closure.
The structure – measuring 60 m long, 25 m wide, and 10 m high, and weighing approximately 8,330 tonnes – was built adjacent to the motorway to reduce disruption. Over a full motorway closure, the entire underpass was slid laterally into its final position beneath the M27.
To enable the slide, approximately 24,000 m³ of embankment material was excavated, equivalent to 10 Olympic‑sized swimming pools of soil. This created the trench necessary for the box to be positioned below the carriageway.
Freyssinet’s role and technical achievement
Freyssinet was appointed by VolkerFitzpatrick to deliver the complete Autoripage® box‑slide operation, bringing specialist expertise, bespoke jacking equipment (from Hebetec a subsidiary of the Freyssinet Group), and precision engineering to one of the UK’s most complex structural slide undertakings.
Autoripage®, Freyssinet’s patented sliding technique, was selected for its ability to:
- Minimise road closure durations by allowing the underpass to be built safely offline.
- Enhance safety by separating major construction activity from live motorway operations.
- Improve construction efficiency, enabling controlled, measurable, and predictable movement of extremely heavy structures.
During the M27 Junction 10 operation, Freyssinet’s Autoripage® system successfully slid the 8,330‑tonne concrete box into place in just 18 hours. This exceptional performance enabled the project team to maintain the tight closure window and deliver the structure precisely to tolerance requirements.
Scope of work by Freyssinet in Autoripage®
Freyssinet provided a full turnkey service for the Autoripage® operation, including engineering, supply, installation, operation, and technical leadership throughout the sliding procedure.
- Design of temporary guiding raft and pushing slab
- Technical support for the Autoripage®
- Design and supply of all necessary components for Autoripage ® including the anchorage blocks, passive/active deviators, steel inserts, strands, Ipalen plate, grease, bentonite etc.
- Installation of the strands for jacking operation.
- Design, supply, installation & commissioning of the hydraulic jacking system.
- Operate the box push operation.
The successful delivery of this box slide demonstrates:
- Freyssinet’s ability to execute large‑scale, high‑precision structural movements.
- The proven efficiency and safety of the Autoripage® system for major infrastructure programmes.
- A significant engineering milestone supporting one of Hampshire’s most transformative highway upgrades.
Freyssinet’s contribution was instrumental in enabling the project to maintain both its engineering objectives and its strict motorway closure programme – delivering a critical structure with exceptional accuracy, efficiency, and operational safety.
Key project figures
| Item | Details |
| Total weight for permanent structure for sliding | 8330 Tonne |
| Sliding Distance | 67.0m |
| Strand | 52 nos. strands x 7 nos. cable |
| Hydraulic jack details | 7 nos. x Strand Jack F1000 |
| Hydraulic pump details | 7 nos. x PA-4-30 |
| Date of Test Slide | 22 December 2025 |
| Date of Main Slide | Start: 26 December 2025 at 12:55 Finish: 27 December 2025 at 07:14 |
| Total Duration for Slide Operation | 18hr 19mins |
| Peak Sliding Speed | ~ 16.8 m/hr |
| Average Sliding Speed | ~ 10.3 m/hr |
Previous Freyssinet box slides
A46 Kenilworth box slide completed – Autoripage
World’s longest box bridge slide completed on HS2 – FreyssinetUK