HS2 Victoria Road Shaft

Doka proves crucial to complex HS2 ventilation shaft construction

01.07.2023 | London, United Kingdom
HS2 Victoria Road Shaft
Leading formwork solutions provider, Doka, is supplying equipment and expertise to ensure the safe, effective delivery of a complex ventilation shaft, a vital element of the ongoing HS2 project which is set to revolutionise rail travel between London and cities throughout the Midlands, northern England and Scotland.


  • HS2_Victoria_Road_Shaft_FromBelow
  • HS2 Victoria Road Shaft
For this large, high-profile project, Doka was selected to supply a specialised formwork solution for the construction of the shaft secondary lining to the Victoria Road Ancillary Shaft. This section of works is being carried out by Skanska, Costain and Strabag Joint Venture (SCS JV).

The Ancillary Shaft at Victoria Road is partially formed by precast rings, the lower section of the shaft’s wall is also concrete-lined. This aspect of the shaft’s composition required the ingenuity of Doka’s formwork solutions to ensure a failproof installation. It was particularly crucial to casting the shaft’s secondary lining which was backed by a waterproof membrane.

Ideal solution to casting conundrum

Due to the shaft’s 25.1m diameter, the secondary lining was cast in five separate pours to approximately 15 meters above the base slab. Securing the formwork and climbing platforms without perforating the waterproofing during the casting process was one of the many challenges given to Doka. The company’s superb D22 single sided “dam” formwork was ideal for this challenge.

Featuring brackets that adapt easily to both inclined and radiused walls, Doka’s D22 system allows for forming casting concrete without the needs for ties. This eliminates the risk of puncturing a wall’s waterproofing. The D22 system’s success can also be attributed to Doka’s technical team carrying out the necessary complex calculations to maintain concrete pressures and deflection tolerances.

The concrete casting process was further complicated by three large tunnel openings. Designed for the train tunnel intersections, these significant openings provided an additional challenge as there was no previous walls to attach the D22 platforms. This issue was overcome with Doka’s Staxo 100 shoring system, an adaptable, easy-assembly load-bearing tower that allows the economical shoring of floor-slabs of widely differing layout.

All-round service benefits

For projects in busy, congested areas such as central London, space is at a premium. Doka was also able to overcome this issue, thanks to its “ready to use” pre-assembled panels and platforms which reduce space requirements on site. Furthermore, the company’s all-round service provision was supplemented by its onsite support, with Doka’s site demonstrator making regular visits to advise the installing contractor, SCS JV, on aspects of its formwork and jump system operation. The guidance was also invaluable in respect of Doka’s Concremote system. The concrete monitoring device uses sensors to measure the temperature and calculate the compressive strength of the concrete structure, thus it was integral to the success of the HS2 Victoria Road project by ensuring the next cycle could be planned and started with increased accuracy and confidence.

Essentially a project for the clients to gain an understanding of Doka’s formwork and long-held experience in that particular field, the Victoria Road Ancillary Shaft project was a triumph for all concerned. The project’s positive outcome meant Doka was selected to provide the same services for a further four ventilation shafts. This is part of its overall contribution to the HS2 project that includes devising formwork solutions for bridges, tunnels and stations.

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