Learning Legacy Podcast: Episode Two – The blueprint and the real thing

Design not only encapsulates the creativity and innovation of new products, but is the main source of information for construction to take place.

Episode 2 of the Learning Legacy Podcast takes a look at the design stages of stations and tunnel portals and encapsulating the importance of finding new methods of work and finding the opportunity to answer questions when there isn’t much existing research out there.

Featuring:

Giles Thomas – HS2 Integration Director
Kim Quazi – ARUP Lead Architect
Fernando Ruiz-Barberan – ARUP Building Envelope Team Associate
José Marquez Santoyo – ARUP Architecture Lead
William George – Jacobs Senior Engineer
Darren Carter – Jacobs Senior Associate Director
Lee Canning – Jacobs Senior Associate Director

Giles describes his role in connecting the teams creating 140-miles of track, 4 state-of-the art stations, two depots and 32 miles of tunnel together, and what HS2 has taken on board from London 2012 and Crossrail to make its Learning Legacy programme most beneficial for the industry.

Kim, Fernando and José take a deep dive into the new Interchange Station, and how cloud-based data sharing allowed for a new way of sharing revisions for major infrastructures gave a new meaning to ‘going back to the drawing board’.

William, Darren and Lee talk through the design process for the largest porous portal in the UK and documenting the challenges and collaboration with external experts in a paper will give other designers a head start when new tunnel portals are built.

Find out more about HS2’s Learning Legacy Programme

Learning Legacy papers featured in this episode

Episode transcript

This is a transcript of episode one of HS2’s Learning Legacy podcast, first published on 28 March 2023.

Rhian Owen

I’m Rhian Owen, and welcome to the HS2 Learning Legacy podcast.

In this episode we’re talking to the people behind one of HS2’s most popular Learning Legacy Papers and going to look at how HS2 went back to the drawing board when planning its design process.

HS2 is Britain’s biggest build, comprising 140-miles of track, four new, state-of-the art stations, two depots and 32 miles of tunnel. As HS2’s systems integration director, Giles Thomas is responsible for bringing them all together.

Giles Thomas 00:46

It’s a role that brings the company together, brings all of the different contracts together and encourages the organisation to use the contractual levers that it has the technical requirements that it needs to achieve and the delivery function and organisation to, actually build a railway.

Rhian Owen

Giles’ role gives him the chance to see each element of the railway coming together in real time and it also means he can see how each step along the way adds to the learning on the project.

Giles Thomas 01:17

Because these programmes are long, and take quite a considerable amount of time to, to design, to plan, to then construct, and then make work. We engage different people at different points along the programme. So we’ve learned a huge amount about ground engineering, from London to Birmingham already.

And I think we’ve learned lessons around construction and safety management. And of course, we’ve also innovated in a number of those areas. And again, those innovations need to be known about, broadcast, talked about, people need the opportunity to engage with the expertise that has come up with either these innovations or new ways of working on new knowledge.

Rhian Owen

While Giles’ job is about making each component of this project come together to create an efficient high speed rail line, HS2 as a whole has the chance to be a lot more. It will provide a step change in knowledge, skills and technology that will benefit the construction industry and other major projects for years to come.

From the earliest days of the project, HS2 has been capturing learning from across the supply chain.

And the earliest stage of most projects is the design.

But not just one design. A single project can go through dozens of iterations, revisions and alterations until there is a final design that the client, the architect, the engineer, and contractor are all satisfied with.

But when you’re building a piece of infrastructure as geographically widespread and engineeringly complex as HS2, this siloed approach to design would simply take too long.

So HS2 redesigned the design process.

Kim Quazi 03:10

One of the things I keep wanting to stress is that HS2 is a hugely ambitious project in so many ways.

Rhian Owen

Kim Quazi is a director at Arup and the lead architect for the Birmingham Interchange Station.

Kim cont.

And in many ways, there are obvious things, there are project requirements, and the technical specifications and, and, and quite challenging requirements. But there is also this idea of creating a step change in, you know, the way we do things. I often describe it as the Apollo Project, you know, its real legacy isn’t really just building a railway, it’s real legacy is allowing us to investigate and think about other things.

Rhian Owen

When it came to bidding for the Interchange design contract Kim and his team at Arup quickly realised that HS2 wasn’t just looking for an architect with nice designs.

José Marquez Santoyo is a Architecture Lead at Arup.

Kim Quazi 03:28

I still remember the first day when Kim came to my desk, saying we have competition to run. I said “What is it about?” It was a train station, a relatively small train station in Birmingham. And we did it at the beginning as a kind of normal competition until we realised that it wasn’t a normal design competition, it kind of encompasses different disciplines at the same time, because the ambition of the client skill set was extremely high for the kind of the short timespan that we had to run the competition. And on top of that, it wasn’t just a kind of design competition in the sense of showing certain capabilities in design, like some sketches, but to show how good our interdisciplinary team was meant to be, in order to kind of work as a partnership. We’re in a partnership with HS2 because this is effectively what HS2 was after, a real partner to develop the team.

Rhian Owen

Building a train station that met all the targets HS2 had set was not going to be easy.

Kim Quazi 05:21

So you know, there’s a very challenging 50% carbon reduction, embodied carbon reduction target, there was very much a kind of huge target around biodiversity and net gain. And, this very interesting idea of, you know, the HS2 design vision of people, time, and place, or people place and time.

Rhian Owen

HS2 wanted its stations to be safe, both during construction and operation, all while incorporating passive design principles.

Fernando Ruiz-Barberan 05:49

And that creates a lot of contradictions in the different performance drivers that you need to articulate in a design.

Rhian Owen

Fernando Ruiz-Barberan is an Associate at Arup’s Building Envelope team. His focus is on the interaction between all the internal elements of the building that separate it from the outside environment.

Fernando also led the coordination of the different disciplines working on Interchange.

Fernando Ruiz-Barberan 06:15

The way collaboration happens is there’s a number of disciplines, there is perhaps a lead discipline—architecture—that starts to define a geometry intent. And that model then is used by a number of disciplines to run the work analysis, suggesting perhaps an optimisation of certain aspects and validation of the design. And that happens usually by sharing files and those files are then developed by different disciplines in isolation.

Rhian Owen

Fernando wanted a new way for design iterations to be shared with all the different disciplines working on Interchange.

Fernando Ruiz-Barberan 06:52

What we did in this project is we also started implementing a cloud based platform that helps us share information differently, right. Rather than sharing files that are silo pieces of information, we share data straight from the designers tools, right. So that’s sort of forced us to develop a much greater awareness of our colleagues we’re doing right. So we shift from isolated file sharing to seamless data sharing.

Rhian Owen

This cloud-based data sharing meant everyone was always working on the latest design, and teams didn’t have to waste days or weeks waiting for a new design change.

Kim Quazi 07:39

And that meant that, you know, the steps between something between somebody proposing something, and it having an impact on another discipline was like, hours or days, you know, it wasn’t weeks. And so, and people were sitting next to each other, and so it was the closest that I think in the digital world, you can get to that point where everyone’s sharing the pen.

The fact that Fernando and Jose and you know, and James and you know, the team that kind of team was kind of just you know, it was like alchemy it was like really what it was like watching magic because you know, you weren’t doing the normal thing where you were playing referee it was just like, wow, this is amazing.

Rhian Owen

Fernando highlights two pivotal factors between using timber structures and implementing passive strategies in the design.

Fernando Ruiz-Barberan 08:29

So there were two main things that were important, right? So timber structure, and passive strategies, right. And those are great on their own, but they are contradictory, right, because passive strategies means you cannot use mechanical equipment to control the internal conditions. And therefore, the variation of the rights, the range of conditions is much wider. On the other hand, you have timber, which is a hygroscopic material which reacts to moisture content variation. So those two, timber wants to have very well defined internal conditions, whilst passive strategies, doing a bit of the opposite, are kind of asking you to relax your expectations, right?

Rhian Owen

But the contradictions didn’t stop there.

Fernando Ruiz-Barberan 09:19

So an example of the most effective area of natural ventilation was the ground floor where people are, and we were delivering that sort of modulation through the entrance door, right. So we have more doors than what was strictly needed for a sort of circulation purpose. So we were able to keep doors open in summertime, to enhance that sort of natural ventilation and deliver that comfort but we could then close them in winter still live in enough openings as required pair sort of circulation occupancy requirements, but limiting the amount of sort of air circulation and sort of heat loss.

However, that is also in contradiction with security and blast strategy, right? Because blasts don’t want to have hinge opening panels in the low level where the greatest threats are right? Backpacks, suitcases, and so on. So there is another contradiction.

Rhian Owen

The design team worked with the HS2 security team to conduct a threat and vulnerability assessment. And construction planning specialists were brought into the design process early and embedded in the design team to ensure the design reduced construction time and risk.

All this is brought together by the digital design software and collaboration tools that are now available.

Kim Quazi 10:49

I think there’s something interesting about shared technology, allowing people to talk to each other, more, more iteratively and more kind of directly, plus the fact that they’re sitting next to each other.

Fernando Ruiz-Barberan 11:00

It forces you to reach some sort of principles that drive the design, you know, earlier on, that gets you to a better place, and to, you know, like, be able to fine tune contradictory performance drivers, in a much more efficient way, and so on, right, and, and that all takes you to a kind of a leaner design, which is also key in delivering sustainable buildings.

Rhian Owen

The result is a station being built with sustainable materials, while incorporating passive design features.

One of the standout design elements is the station roof. The roof is made of a series of interlocking diamond shaped leaves, this shape helps capture rainwater into a harvesting tank for reuse.

And the design is completely modular. This means each roof segment can be constructed in a more controlled environment, reducing costs and risk by minimising working at height. Then the process on site is more assembly than construction.

All this resulted in the Interchange Station becoming the first train station globally to ever achieve BREEAM outstanding status.

The Building Research Establishment Environmental Assessment Method or BREEAM is a measure of sustainability for new and refurbished buildings. It evaluates a building’s performance against a broad range of environmental criteria, from carbon emissions, to resiliency, to impact on local biodiversity.

And receiving Outstanding puts Interchange in the top 1% of most eco-friendly buildings in the UK.

But Kim says achieving BREEAM Outstanding isn’t the most impressive part.

Kim Quazi 12:42

So in itself, there’s not a single little thing. There were a number of things around, you know, kind of civils infrastructure and taking concrete out of the ground and working with the site typography, and, you know, kind of philosophy of touching the ground lightning, which was one component of it, then there was this part of, being able to deal with this sort of these kinds of contradictions, and try and resolve them. But actually, I think the really important thing around having a digital workflow was that it allowed us to drive cost out. So the story isn’t that we’ve done BREEAM Outstanding, the fact is that we have done BREEAM Outstanding at no extra cost. And once you’ve done that, you know, everyone else is saying, Well, can we do it?

I think that’s, you know, that’s, that’s the, that’s the legacy, you know, in a way, I think the important thing for us is legacy is really about saying, “Look, we all need to work like this, because this is a step change. And potentially, if everyone’s working in this sort of digitally collaborative environment, the benefits are huge, you know, they multiply their way across an entire industry, and you know, and then go into other things, where we can drive to, you know, we can improve carbon outcomes, we can remove carbon, both embodied and operational, and we can design to cost how we can have better outcomes for people.”

Rhian Owen

It wasn’t just the stations that presented design challenges, other assets up and down the line had their own unique problems that needed to be designed out.

As a high-speed train races along the track, it pushes through the air in front of it.

The air spirals off the front of the train, its energy dissipating. But what happens when a train travelling at more than 180 miles per hour enters a 16 kilometre long tunnel?

There is no space for the air to be displaced. Instead, it is pushed in front of the train.  As the train heads on, the pressure in the tunnel builds. And, at the exit to the tunnel, the air in front of the train expands rapidly outwards. A shockwave forms, causing a sonic boom.

Boom!

At least, that is what would happen without a tunnel portal. A tunnel portal extends out from the tunnel, controlling this movement of air. It helps solve a problem that engineers only became aware of when the first high speed trains were launched. On the European mainland, other high speed lines have used portals, but these have not been at the size needed for the Chiltern tunnel on HS2.

William George 15:22

One thing that does impact is speed. So they were obviously built a certain length of time ago now, where train speeds weren’t at the 320, 360 kilometres an hour that they are now. And we all—well most people know—the sort of the design journey of the Japanese bullet train and how that has his this great big nose at the front of it. And the reason why that was required was because after they built their tunnels, I think in the 60s, when they were constructed, they had this phenomenon of tunnel boom, and they went away, and instead of having a civil engineering solution, they challenged their engineers from a, what can we do to the shape of the train to mitigate this buildup of nose pressure?

Rhian Owen

This is William George, a senior engineer with Jacobs, who worked on the design of the Chiltern Tunnel.

Along with his colleagues…

Darren Carter  16:16

Darren Carter

And…

Lee Canning 16:18

Lee Canning

Rhian Owen

who are both senior associate directors at Jacobs. The three of them have written a paper together for the learning legacy project, looking at the design of the Chiltern Tunnel South Portal.

A paper like this illustrates the value of a Learning Legacy programme.

William George 16:35

It’s the first porous portal ever built and constructed in the UK. The examples that exist on the continent are a lot smaller, as in maybe 20 metres long.

I don’t know if it’s the longest portal in the world

But like I say, the examples that I’m aware of on the continent are considerably shorter.

Lee Canning 16:57

Partly why we were eager to write this paper was because we, when we were right at the beginning, we looked around and there wasn’t much information available for, for the engineers and the professionals. So we thought, it’s definitely worthwhile to share what we’ve learnt.

Rhian Owen

The length of tunnels like that through the Chilterns, prompted the need for an innovative portal design. For this portal, a porous design was needed, with vents along the top and sides.

While this was a novel project, Jacobs didn’t start with a blank slate. Instead, they worked from specifications developed by HS2. These included expert advice from a computational fluid dynamics, or CFD, consultancy.

Darren Carter 17:40

HS2 have contracted a consultant to undertake some what they call computational fluid dynamics to understand exactly how the air moves within the system, both from the beginning of the portal, through the tunnel, through the shafts and out the other end of the portal..

Once you’ve determined exactly what the structural form will be, how the various parameters work together, you then feed that back into the CFD model. And you get a kind of thumbs up or a thumbs down from HS2’s consultant.

Rhian Owen

The design would need to meet the requirements set out in these documents. At the same time, it was necessary to consider how the portal would be built, alongside the tunnel being bored.

Darren Carter 18:22

We knew there were certain parameters we needed to consider within the various options. And we knew there were various shapes, and vent locations that we needed to consider.

We were very much in this kind of scheme design kind of phase. So we would go through a process where we would present to what they called an IPT, which is an integrated project team. So it was us, Align, and HS2 all in the same building. And we agreed a set of a set of classifications, groupings that they would score the various options against.

Rhian Owen

The integrated project team settled on an overall design for the tunnel. The next step in delivering the portal was to consider how it would interact with the giant tunnel boring machines or TBMs, that were, being used to dig the 20 kilometre tunnel.

William George 19:12

One of the biggest driving factors of the Chiltern Portal was launch of TBM and everything that went in to launch those TBMs.

Rhian Owen

The portal would be mounted on a concrete slab. Assets on HS2 are designed for a 120 year lifespan. Every time a train passes through the portal, pressure will put strain on the concrete and steel structure. So this slab needed to be strong. But it also needed to allow other work to continue on site.

Lee Canning 19:42

The TBM and the construction plant that goes with that, pretty much pretty much defined what that large slab had to be.

Rhian Owen

Before work on the portal could begin, the team had to consider how the TBM would be launched.

William George 19:57

To facilitate the launch of the TBM, the slab was built, the head wall was built and the tympanum was built. And then there were also elements called shifting ways, which were basically geometrical shapes to support parts of the TBM machine. So the backup gantries of the TBM machine.

Rhian Owen

In traditional architecture, a tympanum is a semi-circular decorated wall, often seen above cathedral doorways. On a tunnel project, it is the arch around the flat surface, or head wall, that the TBM first engages with as it breaks into the ground.

The Jacobs team would have to consider how the tympanum would fit within the starting point for the portal. The shifting ways and other elements needed to launch the TBM would need to be incorporated into their design. And they would need to find a way to connect the portal walls to the slab, without masses of rebar preventing site movements.

Darren Carter 20:52

You can imagine sort of the… we’ve got this expanse of flat base slab concrete that needs to have reinforcement coming out of it so we can start all the permanent works. So how do we go about detailing that, so that we’re not, we haven’t got people sort of tripping over or falling over and seriously hurting themselves, that there was a lot of detailing around that reinforcement.

William George 21:11

We extensively used couplers, in the slab. So to prevent any starter bars, any, any rebar protruding out of the slab, to build the walls, which was obviously for the permanent scenario, and to facilitate crane movements going anywhere where they wanted to go on the slab. Yeah, we used couplers, so coupler bars, which are sorts of sockets, and your rebar that you’re then going to attach to, it’s threaded.

Rhian Owen

The expert advice of the computational fluid dynamics consultants, HS2’s overall design criteria, and the practicalities of building one of Europe’s longest high speed rail tunnels all had to be considered. Working with the integrated project team, Jacobs refined its design.

William George 21:58

The top half is a semicircle. And that curve matches the tunnel in, in size and shape. And then the bottom halves are vertical walls. So to to achieve that increasing area, the wall height essentially just increases linearly from tunnel interface to open end of the portal.

There was a bit of a presumption from our team that “oh well, a buried option is going to be the preferred because you can’t see a buried option of course”, erm, but then after various workshops and architectural import and actually understanding from viewpoints, what are you going to… what’s the general public actually going to be able to see?

Rhian Owen

The finished design met the aerodynamic requirements of the portal. It would flare upwards at a consistent angle, until the portal opening was one and a half times the area of the tunnel exit. It would also not stand out against the landscape, but would present an elegant structure when visible.

Lee Canning 22:58

There’s a balance of the engineering and aesthetics and the aerodynamics. There was a feeling, a feeling at the time, it’s very early on in the design process, but an arched structure is more efficient. So there’ll be some form of cost/benefit, perhaps, maybe slightly more difficult to construct. Although we’ve managed to, you know, with the flared option, we came up with the vertical flare, that helped make the construction as efficient as possible, by having the same semi, semi circular shape all the way down.

Rhian Owen

These factors all contributed to how the portal would be built.

The design challenges didn’t stop at this point. Later in the project, it was determined that a crossover slab would need to be built close to the portal slab. The crossover slab supports tracks where they cross. Each slab must be designed for the project’s 120 year life span, so it was vital to consider their interaction.

Throughout the project, the team saw the value of an integrated approach.

Lee Canning 24:00

One thing that I learned along the way was, it may seem obvious, but being open with your partner, particularly between the constructor and the designer, you need a lot of openness. And sometimes that needs a bit of bravery outside your comfort zone.

Darren Carter 24:16

One of the main things I think has made this contract a success is the introduction of what they called an IPT, which was an integrated project team. And that was every decision that was made, you had people from the design team, had people from the contracting team, who were Align, we were Align D,  and you had representatives from HS2, who were, who were in positions of authority to make decisions. And having those three parties at the table for every significant meeting, just move the design along and kind of reduce friction and you had to be brave and you had to be honest, and speak your mind. But I think it progressed. It progressed at a rate that was quicker than my experience on more conventional contracts.

Rhian Owen

These and other topics are considered in detail in the paper that Wiliam, Lee, and Darren wrote with their colleague Robert Browne, for the Learning Legacy archives. The paper will give other designers a headstart when new tunnel portals are built. But it will also support the design and construction of other assets using similar techniques.

William George 25:25

We needed it at the start, didn’t we? We looked for the information. And it wasn’t there. It’s applicable to, you know, almost every structure type, I suppose, isn’t it? No one would usually design a 200 metre long structure without any joints in for movement, but from a durability perspective and a maintenance point of view we took these statuses and made these decisions. And then that that, you know, it produced design issues that we had to solve basically, and they’re not going to be limited to tunnel portals. They’re applicable to many other, I’m sure, other other structures that would need to be developed by others.

Darren Carter 26:07

I would agree with the idea of a learning legacy. Now over the decades that I’ve been an engineer, we have grappled with lessons learned, project sheets, corporate amnesia, just grappled with it. And then the number of times we’ve gone in, and we’ve, we know, we’ve done it before, but we can’t find the evidence that we did, or, or any kind of indication of how we how we need to do it again.

Rhian Owen

Projects like the Chiltern Tunnel Southern Portal and Interchange Station are proof that a more collaborative and integrated approach to design and construction, along with new technology and software can result in infrastructure projects meeting numerous sometimes seemingly contradictory goals.

And now the wider industry has the opportunity to learn, implement and even improve this approach to raise the bar for the UK’s design and construction industry, making it more efficient than ever.

Kim Quazi 27:03

It is really important to tell them to the world, the extraordinary things that are happening, not only in our project, but throughout the line and the thousands and thousands of people who are working on the project and they all have been given the opportunity to innovate and drive things forward.

Credits

Rhian Owen

I’ve been your host Rhian Owen. Thanks to our guests Giles Thomas, Kim Quazi, José Marquez Santoyo, Fernando Ruiz-Barberan, William George, Darren Carter, and Lee Canning

You can get more detail on all the topics featured in this series by taking a look the HS2 Learning Legacy website, we have provided links in the episode description.

Learning Legacy Podcast: Episode Two – The blueprint and the real thing

Learning Legacy papers featured in this episode

Episode transcript

This is a transcript of episode one of HS2’s Learning Legacy podcast, first published on 28 March 2023.

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