Hi, I'm Karine.
And, I'm Ben.
We're both tunnel engineers
on HS2’s Chiltern Tunnels.
We're here today to celebrate
a huge milestone, as each TBM
have reached the halfway point of the 10-mile drive.
We're going to get into one of these buggies here
and take you into the tunnel to show you the progress that we've made.
[ON SCREEN CAPTION] The 10-mile Chiltern Tunnel is the longest tunnel on the HS2 route.
[ON SCREEN CAPTION] We're using two tunnelling machines, Florence and Cecilia, to build the tunnel.
So, we're now about 300 metres from the TBM.
We can't drive any further,
so we're going to walk from here to the TBM and
show you around down there.
So we've just arrived at the back of Cecilia
we're on gantry 6 here, about 8km into the tunnel.
As you can see around us
it's quite a busy, noisy environment down here.
We've got the service pipes here, and the tunnel lining.
So this is just one of the 28,000 segments we’ve installed in the tunnel.
These are service pipes in the tunnel.
So we've got Bentonite comes down, which we put into our grout mix.
We've got two dirty water pipes,
for getting all of the water off the machine.
We've got two cooling water pipes at the bottom
which feed cooling water in and out to the TBM to keep
all the drive motors and hydraulics cool. On the other side of the tunnel,
here we've got the two slurry pipes, we've got the feed, the return,
and we also have recycled water on top of that which we can add into the slurry mix
to reduce the density to make it easier for us to pump out the tunnel.
We are at the front of the machine, in front of Cecilia.
The team has just installed another ring in the tunnel.
This segment is one of the 28,000 segments
that we installed so far.
So one ring is made of seven segments. Those segments are precast at the precast factory
outside of the tunnel
and they are supplied via MSV (Multi Service Vehicle)
to the tunnel, to the TBM.
When they arrive at the TBM
they are loaded on to the segment feeder
on to this area, which is the erector area where we are building the rings.
These segments are 2 metres long.
So one excavation is 2 metres.
We’ve installed on each tunnel, 28,000 segment and 4,000 rings,
which corresponds to 8 kilometres for each tunnel.
The TBMs are running well.
We are installing on average around 8 or 9 rings per shift,
so we are on an average of around 32 to 34 metres per day.
So at the moment we're advancing forwards.
We're doing about 60 millimetres a minute, which
trust me is quick for a TBM.
In about 35 minutes,
we'll have advanced 2 metres and we'll have made room to build the next ring.
So we'll build the ring and then we'll repeat the process all over again.
So for both machines, we've excavated just over a million
cubic metres of material to reach the halfway point of the tunnels.
All of that material is being excavated in the cutter head,
pumped out to surface and treated in the slurry treatment plant.
We're about to install another 2 metre concrete ring here,
so we're going to leave the team to it and head out to surface
and see where all of these concrete segments are made,
at the precast factory.
We're now back at surface at the precast factory in the precast yard.
To the left of me here,
you can see the stack of segments that are loaded onto the MSVs,
multi-service vehicles, with the gantry crane over there.
They're sent into the tunnel and then used to build the lining of the tunnel
as the machine progresses.
In total, we need 112,000 segments
to build the 10-mile tunnel.
So far we've installed about 56,000 and we've got a good stock here
and they're still producing them to get us to the end of the tunnel.
So in the background you can see the
back of the STP (slurry treatment plant).
All of the material excavated by both TBMs is treated
and processed by the STP
and then we use all of it for landscaping, so there is no waste.
So here we are back at surface, the tour’s come to an end.
I hope you've enjoyed the update
that we've given you on the progress of our tunnels.
We're looking forward to giving you more updates
in the future as the work progresses.