On the london underground - what does the dial in every carriage measure and why is it..

D

Dipsydumdoo

New member
...there? Ok, so I was on the London underground at the weekend and one of the things I noticed was that in every carriage was a little dial/clock type face that measured, what i'm assuming is pressure (the numbers ranged from 0-10+ i think and the measurements were in bars - the dial then fluctuated up and down as we went through the various tunnels)

The question is - is it pressure that these dials measure?
If so, why are they in every carriage? I can't imagine them being useful to commuters/general members of the public so why are they there?!

Thanks in advance for any answers :)
 
Back
Top