HS2 reveals first components of ‘giant lego’ lightweight modular viaduct in Kent

This post was originally published on this site

The structure’s elements are being manufactured offsite at a local factory before being slotted together on site “like a giant Lego set”, cutting its carbon footprint by around a third.

The company yesterday revealed imagery of the first of 68 giant 42t supporting piers that will support a structural design of two 25m long 97t hollow beams per span, cutting the requirement for carbon-intensive concrete and steel, while simplifying work on site. Early plans for the viaduct were revealed just over a year ago, as part of HS2’s “zero carbon from day one” strategy.

The modular structure is being described by the company as “a move that represents a major step forward for viaduct design in the UK.”

The larger pre-cast beams that will be used at Thame Valley can be secured directly to one another, removing the need for the diaphragm, improving durability and reliability, saving time, cutting cost and improving safety by reducing the need for people to work at height. Traditionally, viaduct beams are secured together above each of the piers with a concrete diaphragm which is cast in situ.

The prefabricated parts are being produced by precast concrete specialist Pacadar’s UK’s factory on the Isle of Grain in Kent, which also produces tunnel wall segments for HS2’s London tunnels. The factory’s workforce has doubled to 200 people to deliver work for HS2.

Tomas Garcia, HS2 Ltd’s Head of Civil Structures, said the modular viaduct would cut embedded carbon in construction, reduce cost and programme and improve safety, performance and durability.

“Thame Valley is a great example of how our contractors are embracing the latest engineering techniques to do just that. It’s great to see the start of work at Pacadar UK and I look forward to seeing assembly begin on site, later this year.”

The use of prefabricated elements on the project takes lessons from the construction of recent high-speed rail projects in Spain; Pacadar was originally established in Spain and Latin America. Ignacio Chicharro, EKFB’s Project Director, said:

“This internationally inspired design is the product of best-in-class collaboration between HS2, EKFB and its design partners, Ferrovial Construction and FC Civils Solutions. The solution is a lightweight viaduct, set low into the landscape that benefits from the efficiencies associated with off-site prefabrication.

“Leaning on our on-site construction partner, FC Civils Solutions, to provide the expertise which comes with building a prefabricated structure, the viaduct will be slotted together piece by piece. Seeing the viaduct piers in production is a great milestone in the programme calendar and we’re excited to see the start of assembly on-site very soon.”

Fernando Aguilar Pírez, Pacadar UK’s Production Manager said:

“This solution is based on a modular design which is widely implemented by Pacadar on previous high speed lines. This contract reinforces our commitment to HS2 and we look forward to working on this project together with FC Civils Solutions and EKFB.”

Thame Valley is one of 15 viaducts designed by HS2 Ltd’s main works contractor, EKFB – a team made up of Eiffage, Kier, Ferrovial Construction and Bam Nuttall – working with on-site construction partner, FC Civils Solutions and Pacadar UK.

Crossing the flood plain of the River Thame, just outside Aylesbury, the viaduct will carry HS2 trains at speeds of up to 360km/h between London, Birmingham and the North. The underside of the viaduct will be just 3m above the ground, with 36 even spans crossing the river and surrounding wetlands.

Like what you’ve read? To receive New Civil Engineer’s daily and weekly newsletters click here.