Two giant 170m-long robots are being assembled as demonstrators camp out nearby.
For the next decade, passengers on new high-speed trains leaving London will just have a fleeting glimpse of the daylight and scenery of the Colne Valley before they vanish deep underground into the Chiltern Hills.
Today, the size, engineering and costs of the £ 98 billion HS2 project are becoming evident in the three-mile stretch between the future tunnel openings in the northwest of the capital: both on the vast construction site laid out next to the M25 in Buckinghamshire, and in the surrounding rivers and woodlands, where demonstrators are still lingering to keep the machines from passing.
In September, after years of preparation, preparatory work and demolition, what was billed as the official start of construction on HS2 began. After the government reconsidered its decision and the go-ahead was issued by Boris Johnson in February, funding was eventually released for the main works between London and Birmingham in the first phase of HS2.
HS2’s biggest single construction site, part of a £ 1.6 billion deal to build only 15 miles of the proposed 330-mile network, lies at Chalfont Road, just off the highway.
Temporary offices and factories are located in an area of bare earth the size of 80 soccer fields where the excavated chalk is processed and the massive concrete segments are poured. The central point resembles a semi-excavated stadium with at one end two circular portals: the beginning of a possible 10-mile tunnel through the Chilterns.
In this arena, two giant, 170-m tunnel boring machines (TBMs) will be assembled.
It has proven to be an epic challenge just to bring this state-of-the-art German technology to the starting line. HS2 won’t put a price on it, but it will cost tens of millions of pounds for each TBM. The transport of the machines by truck and ship from the Herrenknecht factory in southwest Germany meant that they were broken down into individual components: the enormous 10.3 m diameter cutting heads had to be cut in half and re-welded on site.
Assembly started last month, and a massive Meccano package that involves a 600-ton crane could take until spring.
“It’s a moving factory,” says Didier Jacques, a Channel Tunnel project veteran and construction manager.
There will be a control booth behind the cutting head, where more than a dozen displays will inform operators exactly what is going on. “It’s pressurized like a submarine so we can work safely underground.”
The two devices, called Florence and Cecilia by HS2 Ltd, are a major improvement over the behemoths used to excavate the Crossrail tunnels in London: not only are they larger, but they are capable of continuous digging to accelerate years of work, as the 7.5-ton concrete tunnel segments are sucked up and swung into position behind the drill head by hydraulic arms.
All the machines helping the operation are further back – as well as a canteen and toilets for the employees inside, and a protective chamber guaranteeing 24-hour survival should anything happen underground. Keeping citizens healthy is a futuristic robot, because of its jaws, called a crocodyl, which eliminates, among other items, the bits of wood used to hold the large parts of concrete at bay.
Not only for the tunnel walls, the segments are baked here, but also for a two-mile viaduct that crosses the Colne Valley and runs southeast into London. The viaduct will cross the lakes and rivers of local nature reserves, while tunnel building will take most of the damage to the Chilterns out of sight and out of mind.
And building, as ongoing protests demonstrate, won’t only impact its final location. In Denham Country Park, power poles would have to be demolished to re-route power lines in their direction, which means building another bridge and a route through a wooded area. The work was momentarily interrupted by an even more complex building last month – this time by demonstrators.
Veteran protester Swampy occupied a mesh nest in a 30-foot bamboo tower erected on the River Colne before police stepped in to end the standoff and allow the construction of the plant bridge to continue.
Now, in the direction of development, more trees lie, including some oak trees where demonstrators have erected tree houses.