** WARNING – this post may make you a little bit jealous **
The thing I’m most enjoying about writing my book is the fact that I now have a completely valid excuse to be an engineering fangirl 🙂 ….not that I need an excuse, but I definitely experience fewer raised eyebrows when I talk transport these days. Anyway. in the past few months, I’ve been lucky enough to speak to the Bill Baker (Chief Engineer of the Burj Khalifa) and Ron Slade (Lead Engineer on the Shard). But last week, I had my biggest fangirl moment yet – when I was invited to the head office of Crossrail at Canary Wharf to meet the Chief Engineer of the entire project, Chris Dulake.
Situated in the heart of London’s second financial heart, the Crossrail offices occupy the upper floors of 25 Canada Square – a location that feels about as far away from a building site as its possible to get. But as I glanced out the windows, the eye-catching roof of Canary Wharf’s future Crossrail station reminded me that we were, in fact, very close to the coolest new engineering project London’s seen in a hundred years.
If you don’t know what Crossrail is, here is a tiny summary. It is Europe’s largest construction project, which started back in May 2009. It aims to deliver high frequency, high capacity train service linking Reading in the west, to Abbey Wood in the east. In order to do this, they’ve had to construct 21 km of new twin-bore tunnels under central London. These huge tunnels thread their way through a packed subterranean city – just think about all of the tunnels for the tube network, cables and pipes for utilities and various sites of archaeological importance. And these are large trains that completely dwarf a tube train. And they’ve managed to do it without closing any existing station. Engineering at its finest. Oh and currently, there are over 10,000 people working on it, across over 40 construction sites. Yep.
Anyway, some months ago, Peter MacLennan, Head of Media Relations at Crossrail (and all-round top bloke) had responded to a very cheeky email from me, asking if I could speak to some of the engineers working on the project. I think my ridiculous questions about escalators won Peter over, and before I knew it, I had a meeting with Chris Dulake in my diary.
Cut to Thursday. A shiny lift and (equally shiny) lift attendant escorted me skyward to Crossrail HQ. Chris’s office has a killer view of the Docklands which I can’t imagine ever getting tired of – he told me that when a giant rubber duck visited the area earlier this year, he could see it from his desk 🙂 Within minutes of meeting, I think Chris has me all sussed out, so we’ve dove straight into equations and whiteboard sketches. The major aim of Crossrail, Chris says, is to do all the work while minimising inconvenience to Londoners. And I see his point – for the most part, all we see at each of the sites is the blue hoarding, and some heavy-lift machinery. But beneath our feet, two tunnels with a total length of a marathon route are being constructed from scratch.
Key to the tunnelling are eight tunnel boring machines (TBMs) which weigh in at 1000 tonnes each. They cut through London clay at the rather impressive rate of 100m a week. It may not sound all that fast when compared to your car, but looking back into history provides some context. It took Brunel 16 years to dig the original Thames Tunnel. Crossrail’s new Thames Tunnel took just 8 months.
Another engineering titbit that I learned about was compensation grouting – this is how the tunnellers minimise the structural damage to buildings while displacing tonnes of excavated material. Every single building that sits along the route of Crossrail was identified and characterised in order to understand how tunnelling beneath it would affect its structural integrity. Where predicted damage exceeded acceptable limits, a cement-like substance called grout is injected into the ground at defined positions in order to firm up the area where settlement is expected to occur.
Anyone who is familiar with Soho Square will be familiar with the central ‘grout shafts’ used to carry out this task (there are four around the square because it is surrounded by historically important buildings). They are dug in identified areas at risk of settlement and manned by small teams. Small-diameter underground pipes which spread out from the grout shaft in a radial pattern allow workers to very precisely target areas which may lose more material than acceptable.
88% of the tunnels are now complete, with the remaining two TBMs planned to complete their journey towards the summer of 2015. Once that is complete, all effort will switch to making the tunnels train and passenger-friendly, with trackbed prep, platforms and access tunnels already in the early stages of development. The trains that will eventually speed through these tunnels in 2018 will be incredibly safe, fire-hardened to cope with even the worst catastrophe (no doubt, with a safety nod to the deadly Kings Cross fire back in 1987) and will be super-efficient, employing similar regenerative braking technology to that used in F1 cars.
I left Chris’s office with lots of things – an invite to come back, a book of papers on Crossrail’s construction and some other awesome gifts. Even more importantly, I left feeling totally inspired by this major engineering undertaking, and more than a little jealous of Chris’s scale models! I don’t want to give away all of the secrets I learned from chatting with Chris and Peter – for that, you’ll have to wait for the book – but there is one last thing….
I’ve been invited to visit some of the tunnels myself!
Cannot. Express. The. Excitement.
Promise to blog about that when it happens 😉