Prompted by mention of this in another thread, I did a search and found this website about London's Post Office Railway.

The site has many interesting photos of stock and equipment, including some historical pictures from the 1930s.

The "Operations" page also has a brief description of the electrical systems used by the railway.

It's well worth a browse.

That's really something Paul.
I saw a documentary on DW TV about a year ago about an underground network, in Germany, run by compressed air, to send mail and other stuff in sealed containers between buildings, but I've never heard anything of it since.
Apparently, there also used to be a system used in the UK in multi-storey Commercial buildings that used a Vacuum system to transport money and other things between floors, have you ever heard of this?.

Ahh yes. Mail tubes. Various department stores here in the USA use those canisters shooting through conduit to bring cash directly to the registers. IKEA and Home Depot come to mind.

The vacuum mail tubes were big around the turn of the century. There were people in the mailrooms whose job was to sort and send out small envelopes in these canisters to the different departments. Most of the mailrooms would be located in the basement.

I've heard that here in the Financial District section of Manhattan, there was a network of large mail tubes to send correspondence and small packages underground. The last I heard was that some telecom utilities wanted to use sections of these abandoned pipes to run telephone cables. Don't know whatever became of this.

Oh yeah, that was called pipe mail here. It's still used in Vienna's biggest hospital. There they have little tube-shaped canisters.

Supermarkets and even small convenience stores here in Ireland use those tubes to transport cash around the store. It makes sense to keep the tills emptied regularly from a security perspective and avoids someone having to go around from till to till collecting it.

Paul,
Sorry about the threadjack.
I was just having another look at the Maintanence section and I read that they actually turn the rails around from time to time, to even out the wear on the rails.
That's good thinking.

The vacuum-tube system was also used by some of the big London department stores in the past.

Mike,
It's a little ironic that you mention the track maintenance. This is in the news here at the moment after increasing numbers of derailments on our mainline railways in recent years.

London is still recovering from a whole series of recent derailments on the Underground (subway) system:
http://www.iht.com/articles/114345.html

About 12 Yrs ago, I knew of an old family high end dept store that at the time used
pipe mail. One of the home reno prorammes used one to transport "beverages" around the house.

I think the mail tube systems are still available. Our local Tesco, which is quite modern, has some such system running from the tills. I suppose its a good secure way of transporting cash off the shop floor. This system also has some element of electronic control, as there are coloured LEDs at each station.

Paul,
We are heading into the Railways "de-railment" season over here, namely Summer.
Oddly enough Paul, there are a lot of Electrified Rail systems in the North Island here, but Diesel still features well down here in the South, there is no such thing as an Electric Rail system in the South, if you discount the Trams in Christchurch!.

Curious. Is there any historical reason for the lack of electric traction in the South Island? (Like separate companies at one time, maybe?)

In Britain it was traditionally London and the the part of England immediately to its south which was heavily electric.

London has the Underground, of course, which despite the name actually has about two-thirds of its tracks at grade level!

The old Southern Railway, (later the Southern Region of British Railways after nationalization) used 3rd rail electrification. The S.R. lines run down to the south coast and were always very dependent upon London commuter traffic, so with relatively short spaces between stations and frequent stops electric traction was ideal.

There were overhead electrification schemes in other regions, of course, but it was only in more recent years that most of the main lines running out of London in other directions were electrified.

Paul,
The South Island of New Zealand has a lot more hills than the North Island(which to a certain extent is as flat as a Billiard table, saving Mt's Ruapehu, Tongariro and Ngarahoe).
But, we only generate the stuff on this Island, the other Island uses it for us!.;D