The UK’s widest tunnel boring machine (TBM) has passed its factory acceptance tests, and will shortly be shipped from the factory in Germany to the UK, to arrive in East London and start digging the Silvertown road tunnel under the Thames.

TBM at Herrenknecht (c) Riverlinx/TfL

The Silvertown Tunnel is a new “pay to use” road tunnel being built under the River Thames, linking North Greenwich and Silvertown, and once open, the tolled crossing is aimed at reducing congestion at the Blackwall Tunnel. However, it has been criticised for the risk that improving the road links will attract more road traffic to the area. Mitigating that, the tunnel will have dedicated bus routes using it with the aim of improving cross-river links by public transport with a fleet of electric buses.

To build the £1.2 billion project, in addition to the tunnel approaches on either side of the river, a giant tunnel boring machine is needed to get under the river.

In general, road tunnels are much larger than railway tunnels, and this new TBM’s cutter head has a diameter of 11.9 metres, which compares to 10.025 metres for HS2’s tunnels and 7.1 metres for Crossrail’s tunnels. It also has an exceptionally heavy tunnelling shield, needed to cope with tunnelling under the river. It weighs 1,200 tonnes, compared to 526 tonnes for the heaviest Crossrail tunnelling shield.

TBM at Herrenknecht (c) Riverlinx/TfL

The length of the TBM is approximately 82 metres, the bulk of the length being the tunnel segment processor and waste removal, plus space for the miners to work, and rest during their long shifts. Although the Silvertown road tunnel will be twin-bore to allow for traffic in both directions, there’s just one TBM being delivered. It will launch from the north side and head to North Greenwich, where it will be turned around to dig the second tunnel.

Construction work is well underway and site operations have been established on both sides of the river in preparation for the arrival of the TBM. The first pieces have already begun to arrive on-site, keeping to programme for launch in Spring 2022. Due to the extraordinary weight of the components, and the location of the sites, just over half of the equipment arriving at the construction sites will arrive by river barges.

The project will excavate nearly 600,000 tonnes of material to form the tunnel – all of which will be taken away by barges along the river where it will be reused to landscape contaminated land at Ingrebourne for a wildlife reserve and also at Rainham Marshes.

Tunnelling is expected to start next spring, and the tunnel should open in 2025.

Silvertown site – with TBM launch shaft just behind the blue building (c) Riverlinx/TfL

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18 comments
  1. MilesT says:

    Will the electric buses be hybrid OHE/BEV (using OHE on approach to, and through, tunnels), or just BEV?

    Conceptually an OHE section would be good for en route recharging and motive power to extend BEV range (avoiding in-day return to depot) but would need to be considered in the design especially if catenary was used as opposed to trolley poles

  2. Uche Mick Chinonso says:

    So Sadiq Khan have the Silvertown Tunnel the greenlight but not the Bakerloo line extension. Yet he has the balls to blame the central government for the TfL financial crisis. This is where those revenues have been funnelled the whole time, people.

  3. Graeme Sergeant says:

    It is private finance to make money

  4. Reyaz Siddique says:

    Making a tunnel within close distance to existing blackwall tunnel looks good but the question one has to ask is whether we could have move the crossing project between beckton and woolwich which could have connected south and north circular and ease congestion on a13 and a2 . Why divert all the traffic to A13 and a2 which is already a congested motorway .

  5. Peter Feltham says:

    Just what IS wrong with british engineering these days.We have spent nearly £400,000,000 in germany on TBMs in the past 15 years.That’s a hell of a lot of money we have given away to them,and all because we are incapable of manufacturing our own Tunnel Boring Machines.

    • Freddie Trumper says:

      Why would we need two countries to specialise in tunnel boring machines? We have tariff free trade in goods. Let Germany specialise in one thing, and we’ll do something else, and we both win.

    • ChrisC says:

      That’s an average of just over £26m a year.

      It’s not that we’re incapable of building them here it’s just uneconomic to build them here.

  6. Peter Feltham says:

    Trouble is….we specialize in nothing.

    • ianVisits says:

      Rolls Royce aircraft engines would disagree.

      The many manufacturers of satellites in the UK would disagree.

      Our world leading medical firms would disagree.

      Etc…

  7. Lawrence Curran says:

    I noticed that not only will this new tunnel be a toll tunnel for vehicles, but we will then also have to pay to use the existing Blackwall Tunnels, one of which was built before cars. This will then stop people choosing to use the “free” tunnels. Seems Khan may then have precedent to start charging for existing bridges…not to mention the ludicrous money grabbing road and parking charges.

  8. Ever the Optomist says:

    What will happen to the TBM afterwards? Will it be worn out and useless or can it be used for other tunnels elsewhere in the country? Why not use it for the Stonehenge tunnel that has been on and off the cards for decades?

    • ianVisits says:

      All TBMs are custom built for the specific tunnel they are working on due to the local ground conditions, and while parts will be recycled, in practice, it’s rare that they are reused elsewhere — and frankly, the TBM as a percentage of the cost of building a tunnel is negligible, so it’s better to buy a dedicated machine optimised for the job than try to save a few million on a second-hand unit that’ll probably cost more in the long run due to being less than ideal for the job its doing.

  9. Thomas Rennie says:

    I don’t agree with this project.Having lived and worked in this area for 50 years I am dreading the volume of traffic that will be heading into this bottleneck.I have been supporting the Thames crossing in Kent to Essex since it was first suggested which I think should have had a greater push for completion than a bottleneck tunnel at Silvertown. Ask all the lorry drivers trying to cross at Dartford,!

  10. Kieron/Helen Mcdonald says:

    Amazing as Khan states the tfl are skint & are closing trains/tubes & bus routes down while driving a 5litre bulletproof Range Rover that’s exempt from his new Ulez & Congestion charges this is also without the Crystal complex costs

    • ChrisC says:

      As already stated the tunnel is being built and paid for using private money with the tolls being used to pay them back.

      The moving to the Crystal will actually save the GLA money as it will be cheaper than staying at the Tower Bridge office as they will no longer have to pay rent (the GLA already owns the Crystal). That and other reduced costs will save £50m over the next 5 years

  11. Ian Smurthwaite says:

    Yet more money invested in covid central London. So much for leveling up the North East England the forgotten land. Nothing changes with the tories with no credible opposition things will stay the same

    • ianVisits says:

      The tunnel is being funded locally by local taxpayers and developers, and when it’s open by local motorists — I see no reason why you think this is somehow depriving the North of funding, nor why your local region can’t do the same as London and fund local transport upgrades locally.

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