wrote:
On Wed, 9 Aug 2017 09:13:29 +0000 (UTC), d wrote:

On Wed, 09 Aug 2017 09:41:23 +0100
wrote:
As a child I liked going to Hounslow West as walking along the pathway
behind the buffers gave you an unusual view of the trains,
I think the only sub surface train I have travelled on the route was
the Steam special from Northfields a couple of years back.

How far can a sub surface stock go down the heathrow branch these days?
Obviously the heathrow tunnels and houslow west are too small for one.

I believe it is Northfields and on occasions a sub surface train
reaches there and has been returned via the depot.
Sometimes the visits have been unplanned.
Hounslow Central used to have the over height detectors just beyond if
a sub surface train ever got that far but in more recent times a
couple of rail over road bridges have been replaced and they were
built to allow passage of stock of tube width but would foul any sub
service stock . The first one is here just west of Hounslow East.
https://goo.gl/maps/FgFoJEYYvd92.

I was wondering about RAT runs on the Piccadilly line. I know the A and in
future the D stock RATs are used for the western Piccadilly line, but I
wonder if they can go further west than Northfields?