Ever since the telephone was invented, it was seized upon by railway companies as a means of communicating to employees at the lineside or involved with train operation. This meant positioning phones at places where staff would likely be working or at signals where trains might be stopped. A whole plethora of phones mushroomed across the railway that contributed to great improvements in railway efficiency.
In those early days, no special telephone instrument had been designed for external use let alone railway applications, so an ordinary desk-type phone, housed inside a wooden case, was used. Very often the phone needed its own power supply which would be a battery in a cupboard underneath the case to energise the microphone and to provide ringing current. These cases frequently became insect colonies and encrusted with dirt.
Phones were used at one’s peril and regular maintenance was needed to keep them in a fit state. Only in later years did purpose built phones in weatherproof cases become available, these being a great improvement for the user.
As operational methods became more sophisticated, so the variety of phones on offer multiplied. A big advance was the invention of central battery (CB) techniques, enabling the phone to be powered from a central source thus obviating the need for a local battery. 50 volts DC permanently on-the-line facilitated both speech and signalling. The introduction of automatic telephony led to external dial phones being developed, again using CB power sourcing. The portfolio of phone types might be summarised as:
» Central Battery with handset lifted off to call or with a calling push button;
» Auto Phone with originally a dial but now a keypad;
» Battery Ringing with either dry or wet cells to provide ringing current, often with code ringing buttons for alerting other phones on the same circuit;
» Magneto Ringing with either a hand cranked generator for high voltage AC ringing current but latterly using a battery and DC-AC invertor;
» Selective Ringing for use on omnibus circuits (more than one phone on a single line) to either decode a specific ringing code or generate an individual identity when calling.
More recent additions have been the GSM-R radio telephone and the VoIP (Voice over Internet Protocol) phone, which are described later. Traditional applications, with many still being needed today, consisted of:
» Point to point circuit, typically between a signalbox and depot, shunting yard, ground frame, etc;
» Signal Post Telephone (SPT) for communicating between driver and signaller;
» Electrification telephone to contact the electrical control room;
» Level crossing telephones for use by staff and members of public;
» Station platform telephones for contacting a control room or signalbox.
Many companies designed and manufactured these phones, often as a proprietary system or as a standard product that mirrored general telecom developments outside the rail industry.
Bespoke designs suffered from early obsolescence risks and the railway got caught out on a number of occasions by buying such products.
A problem of the past 30 years has been the vulnerability of phones to vandalism and a number of design variants have emerged to combat this menace.
The situation today
Lineside telephones remain part of operations culture, with other means of communications still being viewed with suspicion in some quarters. The supply market in the past was dominated by Plessey, Racal and STC but none of these companies (or their successors) are still in the external telephone business.
Alternative supply sources have emerged, the most significant one being GAI-Tronics, a company formed as long ago as 1946. Based in Burton on Trent, it has been part of the Hubble Corporation since 2000 and Rail Engineer recently visited the company’s premises to be greeted by sales manager Harry Kaur and marketing assistant Agnese Upeniece.
The company has 144 employees, all centrally based, with most of the staff being engaged in design, engineering and manufacture. With this head count, GAI-Tronics is a medium size company and is able to take on a number of apprentices each year, thus doing its bit for local youth.
Whilst the rail sector is important, it is not the only market needing external phones – motorways, oil & gas, shipping both merchant and Royal Navy – all add up to a considerable demand every year.
Network Rail has approximately 32,000 phones at the lineside and a goodly number of these have to be replaced each year, either because of age, or vandalism, or because projects to renew signalling or level crossings incorporate new telephones. The types of analogue phone have been rationalised over time and are now all based around CB or Auto operation, but with a number of configurations being available.
Network Rail is the final customer for all lineside products with Unipart Rail being the GAI- Tronics distributor. If phones are required as part of infrastructure projects, then companies such as Telent, Thales, Atkins, Babcock and BAM all purchase phones as required.
There is a strong requirement for Passenger Help Points for public use on station platforms. These are hands free, incorporate an induction loop, large tactile buttons and raised text including braille, and are positioned to be accessible for wheel chair users. Connection can be made to either the emergency services or to rail enquiries, allowing passengers to access information during their journey.
So what’s in a phone?
The basic components of a lineside phone have remained essentially similar down the years: a metal housing; some electronics to power the transmitter, receiver, and inward and outward calling signals; a handset and a mounting bracket. That said, there are many variations on the theme.
Off-hook calling with CB phones can be a problem if the handset is not replaced after a call. Telephones can be designed to automatically go back ‘on-line’ after a pre- determined time (SPT – seven minutes, Level Crossing phone – three minutes).
Number calling keypads are manufactured so as to protect against moisture ingress. Handsets are made of durable material that can withstand harsh handling and, where vandalism is likely, the handset cord is armoured. Casing doors are now spring-loaded and self-closing. Additional protection can be the provision of a lockable door opened by a BR No1 key or housing the phone in an anti-vandal housing.
Phones are designed for either pole mounting using metal banding strips or wall mounting by screwing through holes in the casing.
For many years, from the late 1960s onwards, the standard phone was the Plessey 745 model, known colloquially as the ‘coffin’ phone because of its shape. This model supplied many markets in addition to rail and came in a variety of types – often needing an additional bolt-on box if there was insufficient space for the electronics of the more sophisticated versions.
Gradually, the 745 was replaced by more modern and better constructed housings, the GAI-Tronics version going under the brand name of Titan. The casings are made from corrosion – resistant cast aluminium and are bought in. Getting good paint adhesion is something of a challenge but the normal colours of grey (for general use) or yellow (for level crossings) can withstand most conditions.
All the design, engineering assembly and testing is done in the Burton factory, giving GAI-Tronic complete control over the quality of its products while helping the local economy.
Lineside phones have to be reliable and robust. They are frequently used when persons making the call are under stress and any ensuing anger or frustration can result in the phone (particularly the handset) receiving rough treatment. This imposes a rigorous test program to prove a design is fit for purpose and GAI-Tronics has an in house environmental chamber as well as employing an external test house to prove robustness of the various designs.
Every production phone is thoroughly tested before leaving the factory. Network Rail also has rigorous test- and type-approval procedures.
To ensure correct usage, telephones must be correctly labelled, both externally to indicate the type of phone and internally to give detail of the operation plus any special emergency numbers. External labels have been standardised over time, typical ones being;
» A handset silhouette for a general purpose phone and if public usage is foreseen;
» Black & white diagonal stripes for SPTs;
» A green background with emergency wording for calling electric control rooms or the emergency services;
» A black St Andrew’s cross on white background for general operational use.
If the phone has to be used at night in dark conditions, then fluorescent labels and instructions are provided.
Instructions on usage will include site-specific details as to the phone’s location plus how to contact an operator or emergency service.
New requirements and developments
Level crossings are the biggest safety risk on today’s railways. Having reliable communication back to the controlling signalbox is important, particularly for members of the public. For Auto Half Barrier (AHB) crossings, special telephone systems have been in existence for many years. Known as PETS (Public Emergency Telephone System), the system is produced by Bombardier (from the original design developed by Whiteley of Mansfield) and is self-monitoring for any fault conditions.
A variation on a standard CB telephone in a bright yellow casing is produced by GAI-Tronics to complement the signalbox concentrator equipment. An alternative supply base is now available known as KETS (Kestrel Emergency Telephone System) which is based on the Kestrel (Wimborne) SPT concentrator but achieves the same result. Again, GAI- Tronics produces the associated telephone.
User worked crossings are, however, a particular risk and these are often on remote lines with no trackside cabling or power. Past attempts to overcome the problem have been a ‘mono dialler’ public-use telephone connected to a rented BT landline where, by pressing a button, a user causes a pre-determined number to be dialled that connects to the signalbox.
Remote BT lines can have reliability problems so replacing these with a radio connection is a logical step, but with the premise that phone usage characteristics remain the same. Thus the development of a GSM (or GSM-R) phone for such locations has been a logical step. Often combined with a solar panel and battery to provide power, these radio phones are ideal for use in rural areas. Being connected to the GSM-R national network, the phones can be monitored and interrogated.
Telephony as a technology is changing and traditional analogue circuitry is being replaced by VoIP (Voice over Internet Protocol). Increasingly prevalent in commercial use, it was only a matter of time before lineside phones adopt this technology.
The first application of VoIP for lineside use has been some SPTs on the Glasgow to Edinburgh line described in issue 119 (September 2014) and for which GAI-Tronics provided the telephones. Whilst such telephones need a local power supply, this is rarely a problem on a main line as S&T power will be available in an adjacent location case.
Being able to connect the phone to the local IP network means the reduction of copper cabling and much greater resilience of routing back to the control centre. Some technical features that VoIP phones offer are:
» Use of widely adopted open standards – SIP (Session Initiation Protocol, RFC3261) allowing ease of integration into existing systems;
» Each phone can register with up to four alternative servers, meaning that if connection to the first server is not achieved, it will attempt to register with others;
» Real time fault reporting and diagnostics;
» An audio path test to ensure the functioning of the handset.
The technology is still under trial and it will need a lengthy period of operational use before final approval can be given.
Arriva Trains Wales has, for some years, been using a VoIP Help Point linked to the CCTV surveillance system at stations so as to operate over the same IP network.
Another initiative is the provision of an IP network aboard trains where the internal phone system, used by train crew and catering staff, can be ‘bolted on’ to the train WiFi package. This latter development is outside the scope of this article but watch this space for further updates.
Future usage predictions
With the growth of radio systems both for track-to-train communication and for trackside workers, many predict that lineside phones will soon become a thing of the past. They do, however, remain a corner stone of rail operational practice and the authorities are reluctant to sanction abandonment of SPTs even though trains have been equipped with radio for many years. With the impending advent of GSM-R as a single nationwide system, it is likely that SPTs will only be required at control signals that protect junctions and crossovers.
Equally, technicians attending infrastructure faults invariably reach site by road transport and use GSM mobiles to communicate back to base, even receiving work packages by text or email messages. Coverage of rail routes by the public cellular radio providers is nowhere near 100% but, with the GSM-R network expanding, the associated radio handsets will provide staff with robust radio coverage at the lineside. Even with this, there remains the satisfaction that a lineside phone will always connect to the required end point.
So, the lineside phone continues to survive and, whilst its numbers will decline, the re- assurance that it gives in conditions when radio systems might fail will endear it to the rail operating authorities for many years yet.