RSN 2021 Exhibitor – Cairn Cross – Completes Oxley Depot Facility Subsidence Works

Working as Principal Contractor, Cairn Cross has completed works for Network Rail at the main maintenance depot shed at Alstom Traincare Facility, Oxley, Wolverhampton. The depot shed had encountered gradual subsidence issues. More recently, some large subsidence movements have caused approximately 137m length of the Road 16 rail pit walls to move significantly, causing the road’s closure for safety reasons. Cairn Cross put forward proposals to replace this section of the pit and associated works.

To resolve this, permanent works designed by others with input by Cairn Cross with the design of the slab remedial works and duck under design. Cairn Cross also created and installed the lighting solutions for the depot.

Pit Removal

To gain safe access to the maintenance shed, we temporarily removed four access platforms to allow plant and machinery the entire length of the main shed and carry out demolition works and new build.

Removal of one hundred thirty-seven meters of rail along the length of the pit to be replaced. The rail, base plates and packers were recovered and stored for reinstatement once the civil engineering works were completed.

All power, lighting, and compressed air services were uninstalled before excavation and stored for reuse later. Removal of the existing concrete slabs and columns using floor saws, hydraulic peckers and excavators.

Constructing the new pit

For Cairn Cross to form the new shed maintenance pit, structural reinforcement formwork was prefabricated offsite in six-metre sections and lifted into place. By creating the formworks offsite, meant the project would run more efficiently and safely. A hydrotite water bar was installed along the centre line of the kickers. Once the walls were poured, struck and made good, a grano screen was installed into the base of the pit to allow fluid to drain to the central gullies. Complying with Health and Safety regulations, two pairs of duck-unders were installed in the inspection pit to aid in escape in the event of any fires within the pit area. The duck-unders have GRP safety handrails installed.


Painting two coats of bituminous blackjack waterproofing on the back of each wall, with 6N material placed in layers of 150mm, each layer compacted and built up to the underside of type 1 level.

H16 dowel bars were drilled and grouted into the existing slab sides at 600mm centres. Visqueen waterproofing membrane was laid out across the new slab area. A 393 mesh was installed to form the slab reinforcement, and joints formed at 6m centres to control cracking.

Laying Rail Depot P-way Track - Oxley

Rail reinforcement

The 137m of compliant reused rail pandrol base plates and fixings were reinstated onto the top of the pit walls with the concrete works complete. The newly formed recesses house the new lights, associated cables and tray work. The compressed air system restored to its previous location. All lights and compressed air systems were tested and certified. To complete the project, joint sealing, floor painting and reinstatement of the rood access platform were carried out.

Paul Brown, Site Manager of the project, shared “it has been a fantastic project to lead. The teams have worked incredibly hard despite the ongoing extended safety measures with the ongoing pandemic. We worked closely with the depot to ensure safety was paramount and disruption was kept minimal. Completing the project works on time demonstrates the hard work Cairn Cross dedicated to the challenge”.

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Cairn Cross
1 Cadman Court
Morley, Leeds
LS27 0RX