Permanent Current Rail Indicating Device (P-CRID)

Tubelines had them designed and installed P-CRID's are not on SSL or BCV apart from where areas are shared track with JNP

SSL, BCV and JNP are/were the three divisions the infrastructure maintenance was split into for PPP named for the lines they would look after (generally speaking at least). SSL = Sub-surface Lines
BCV = Bakerloo, Central and Victoria
JNP = Jubilee, Northern and Piccadilly

Metronet won the SSL and BCV contracts, Tubelines won the JNP contract.

I can't help with P-CRID.

edit: PPP = Public-Private Partnership, the ill-fated outsourcing of London Underground maintenance.

P-CRID = Permanent- Current Rail Indicator Device

These were fixed either by the track or on a tunnel segment

They have 3 indications OFF ON FAULT

They are permanently connected to the traction rails and were only used by JNP Tubelines staff upto approx 5 years ago when LU started to add the training to the relevant track courses.

www.unipartrail.com/assets/st-crid.pdf

If you're old enough to remember "the answer is yes now what's the question?"

Doesn't the thread title give it away?

Glad he did.

As far as I knew it was a Programme Content Reference IDentifier.

as opposed to a

As far as I knew it was a Series Content Reference IDentifier.

(They are something sent with digital TV signals to enable PVR's to work.)


Nowadays, even doubly extended TLA's are being reused!

I didn't say they were perfect nothing is can't beat a true analoge multimeter though

If you "plug in" an analoge meter in the "wrong way round" you should'nt be using one

The portable CRID is generally known as a 'box of bulbs'.

Nothing stays the same.