On Mon, 22 Feb 2021 22:57:48 -0000 (UTC), Recliner
Post by Recliner Post by Peter Able Post by Recliner Post by Basil Jet
If you mean the T5 tunnel, I imagine they're the only part of the tube
constructed with NATM.
Parts of the central HEx station famously use NATM, but I don't think any
of the Tube or HEx running tunnels used NATM. They look like normal deep
bored tube concrete ring tunnels, as used on the JLE and probably the
Those T5 tunnels are fairly shallow and have heavy airliners parked or
taxiing above, so I wonder if they use a more sturdy construction than
usual tube tunnels?
Might be of interest?
Thanks, it confirms my observation (though I'm surprised a few other
stretches are shown as even noisier), but I wonder what explains it? These
are new, smooth, straight concrete tunnels, probably with a slightly larger
diameter, so one might expect them to be smoother and quieter than
century-old steel tunnels.
I'd have thought that a tunnel with smooth concrete walls was just
about the noisiest possible space, the diametric opposite of an
ISTR that Victoria Line getting some flack in 1969 with people hoping
that the first new line for 60 years would have demonstrated some
progress in noise reduction. It hadn't and it seems little has changed
as the Jubilee and T5 prove.
I wonder how Crossrail will pan out?
I find that noise map curious. It suggests that open air sections are
in some cases over 80dB, noisier than some tunneled sections. That
doesn't match with my experience. When entering the tunnel at
Southgate or Arnos Grove, for example, the noise levels subjectively