Monday, 9 November 2015

Electrification Telephone Systems for British Rail


In the post Starting my own business I described setting-up a business and being awarded, in 1970, our first order for selective call telephone equipment from the London Midland region of British Rail. This equipment was for use in connection with the provision of new Power Signal Boxes at Warrington, Preston and Carlisle.

Electrification Telephone Systems for Crewe

Because the West Coast Main Line was being electrified at 25 kV 50 Hz, there was also a need for a separate system of 'Electrification Telephones' with its own, distinctively-marked weatherproof telephones connected back to the Electrical Control Room (ECR) located at Crewe. This control room, often called the 'Electric Control Room' or, more usually, just 'ECR' had been built by British Railways as part of the earlier Euston to Manchester Electrification Project. The ECR was located within what was then called Crewe District Electric Depot, on the down side of the Chester line, in between Crewe North Junction and Crewe Steel Works signal box.
When I returned to the site in 2008, the ECR was still there but the whole site had become Crewe International Electric Maintenance Depot (or Crewe IEMD) operated by E.W.S. See my report here.

Crewe IEMD: View of the yard taken from within the depot in 2008.
The 'Electrification Telephones' were placed at regular intervals along the route for use in the event of emergencies involving the Overhead Line Equipment (OLE). 'Electrification Telephones were also located at OLE outdoor switches and Track Section Cabins (TSC).

In designing the original selective call equipment, we'd had to solve the problem of reducing the power consumption of the signalling decoder so that all the telephones on a circuit could be powered from the telephone line, eliminating the need for batteries at each telephone. But the requirements for the Electrification telephone system were harder to meet since it was also necessary that a number of telephones on the same circuit be able to join in the same conversation. This meant that we needed to reduce the power consumption of the speech circuit so that, when a call was in progress, the telephone line pair could supply power to a group of telephones engaged in the same conversation. After more development, we were satisfied that we could meet these requirements and tendered to the London Midland region of British Rail for a system covering 300 route-kilometres of electrified railway.

We won the tender and in 1971 were awarded the contract to supply Electrification telephones, repeaters, terminal racks and central operator consoles for use on the line from Weaver Junction (south of Warrington) to Carlisle. Production of this new order overlapped the first order for selective call telephone equipment which we'd started to work on in 1970.

Electrification Telephone Systems for Cathcart

The Electrical Control Room at Crewe was responsible for the line as far as Carlisle but electrification was being extended to Glasgow. There was a second Electrification Control Room at Cathcart, around three miles south of the centre of Glasgow. Later in 1971, we were invited to tender for the supply of a similar system for the Scottish Region of British Rail covering 200 route-kilometres of electrified railway controlled from Cathcart. We received the order for that system, too, so we were kept quite busy with three overlapping contracts for selective call telephone equipment.

The requirements for Cathcart included the supply of a Cord Switchboard - a manual switchboard with plugs and jacks to allow a number of calls to be routed simultaneously by the operator. Apparently, a number of earlier Electrical Control Rooms involved the use of a Cord Switchboard and it was a feature the client wanted to retain.

We still had plenty to learn about conventional telephony systems so another period of intense study was called for to enable us to work out how we could adapt a standard Cord Switchboard (designed to interconnect a number of Central Battery telephones to a group of outgoing junction circuits) to our selective call systems (designed to work with keyboards). My starting point, as always, was to consult the two volumes of the book 'Telephony' by J. Atkinson.

Back in the 1970s, there was no internet, of course (there's a splendid brief history of the internet by the Internet Society here). Today, you can research any topic with a few clicks and it's an amazing asset but conventional books are essential as well. There's a brief introduction to telephone switchboards on Wikipedia here but see also A manual telephone exchange: CBS2 on John Hearfield's good-natured and quirky site.

Plessey still made standard cord switchboards so we ordered one of those and, after some sleepless nights, came up with a design for a small sub-rack with reed relay interfaces mounted on plug-in circuit boards which we installed in the back of the switchboard.

A similar Cord Switchboard
(Photo: The Telephone Museum).

In general, British Rail performed their own installation and testing of our equipment but from time to time we were involved in visits to various sites to assist. Needless to say, I was always delighted to have an opportunity to poke about on a railway. However, for the Scottish Region project, whilst the railway were installing the telephones, they wanted us to install the cord switchboard and commission the whole system. Usually, two or three of us would fly up to Glasgow from Birmingham, we'd beaver away for a day then fly back. This was in the days of British European Airways (BEA) before they merged with BOAC in 1974 and became British Airways. Originally, they had Vickers 'Viscount' turbo-props on the route but later they were replaced by the Hawker-Siddeley 'Trident' with three Rolls-Royce 'Spey' jet engines.

I remember one trip when we took a huge, steel deed box as luggage. We'd crammed it with installation materials, tools and test equipment. It took two of us to move it but, to my surprise, the airline handled it without demur. No 'enhanced airport security' in those far-off, innocent days.

We managed to install and locally test the cord switchboard but Scottish Region were having problems completing their lineside cable system over which our telephones would operate so that we were delayed in completing commissioning. I began to understand their problems one day when, having been assured all was ready, we flew to Glasgow. On our arrival, they apologised and said that a section of recently-completed telecommunications cable had been stolen overnight and we'd thus have to postpone our testing. Apparently, they always made sure that cable was jointed the day it was laid, to discourage theft, but sometimes determined thieves would just hacksaw through the cable in a couple of places and carry away a section to 'scrap-in' for the copper. Live power cables were not immune from theft, they added. Perhaps not such innocent days, after all.

I'm pleased to confirm that, eventually, we were able to complete our commissioning.

Electrification Telephone Systems for Hornsey

In 1974, we received an order for one more system of Electrification Telephones for British Rail. This was for the Great Northern Electrification Project for the Eastern Region, covering 100 route-kilometres of electrified railway. This system was controlled from an Electrical Control Room at Hornsey, about four miles north of King's Cross, London. For this project, we supplied telephones with mounting plates plus repeaters, terminal racks and a Cord Switchboard (similar to that supplied for Cathcart). For this project, we also took responsibility for all installation and commissioning, including all the lineside telephones. Handling all aspects of installation gave a new dimension to this project and I'll write a little more when I can.