On Fri, 30 Oct 2009 02:45:56 -0700 (PDT), Uncle-C wrote:

I'm unsure about the rules and regulations on this one but yesterday I
wanted to go from South Ruislip to Acton Mainline, the obvious route
being South Ruislip (LO) - Greenford (FGW) - Acton Mainline. Prior to
starting off I checked with the ticket clerk at South Ruislip to
confirm Oyster's validity on the route and was cheerfully told that
all that was needed was for me to touch in at SR and touch out at
Acton Mainline - the journey should be resolved as a Z5-Z2 fare i.e
£1.10 ( I was travelling Off Peak).

Correct.

On reaching Greenford I
disembarked and while waiting for the FGW to Paddington noticed the
yellow Oyster validators with a sign above them stating that all
passengers should touch in or be faced with the prospect of a £20
Penalty Fare. Being slightly wary I checked with the platform staff
and the ticket clerk in the booking hall who both kindly said that I
would need to touch the Oyster pads and that the South Ruislip -
Greenford - Acton ML journey would be resolved as one. Having been
told different at South Ruislip I took a chance and touched the Oyster
Pads beside the FGW platform and to my horror it registered as a
completed journey (EXIT STATUS) and deducted my fare.

It deducts the South Ruislip - Greenford fare, in case this is the end
of your journey, but it also leaves open the possibility that you're
still in the system, so when you touch out at AML it should adjust the
fare you've been charged to the SR-AML one.

Luckily there was no inspector on the train

You would have been fine...

and when I got off at AML and tried to
touch out I got a repeated error.

Sounds like it's broken - in which case it's lucky you touched at
Greenford, otherwise you'd have been left with an unresolved journey
from South Ruislip.

No funds were deducted for the
Greenford - AML leg. I later checked my Oyster travel history and it
only showed a South Ruislip - Greenford completed journey and no
mention of either South Ruislip - AML or Greenford - AML journeys.
Could someone kindly clarify matters on this. It seems to me there is
no need to touch the Oyster pads at Greenford if you are changing from
LU to FGW but you may need to if you have a non-oyster ticket on the
FGW and are changing onto the tube. So why the scare tactics forcing
everyone to touch the pads prior to boarding the FGW train.

It's to keep the instruction as simple as possible, as there's no harm
in always touching (even if you're not starting or ending the PAYG
part of your journey, or have a Travelcard on your Oyster and are not
using PAYG at all).

There are a lot of people out there (even ones who aren't totally
thick) who have great trouble understanding even simple instructions.
E.g. I know someone who runs their own business, but would be utterly
baffled (and slightly angered) by an instruction like "touch here only
if changing between LU and NR and using PAYG for the LU part of your
journey and another ticket for the NR part".

This will
only lead to a complete journey resolution and hence an oyster card
check on the train will show that you have got onto the FGW without
"touching in" anywhere !

Interchange validators don't completely end your journey.