The history of railway communications in New Zealand is reflected in the increased sophistication and diversity of the technology used to carry information around the operating system. The technology in turn reflects the changing demands of an operating system responding to the increasing complexity of information required for effective train control, and for the efficient management of all resources applied within the business.
From Galvanised Wire to Fibre-Optic Cable
When the Railways Department was established in the late 1880s, single galvanised wires, using the earth as a return, carried morse and telegraph communications between the few private, provincial and government stations. Only one message could be sent at a time, one way, providing minimal information about movements of the few trains on any one railway track. Two-way communications followed with the gradual installation of a second telegraph line between stations (described in annual reports of the time as the 'metalicising of the circuits'- it replaced the earth return) and the introduction of increasingly sophisticated telephones and exchange systems plus the installation of frequently-spaced, manually-activated track-side phones.
In stations where there were several phone extensions, exchange systems were installed to allow users to interconnect between exchanges or other phone extensions. Initially, these were entirely manual. The user turned a handle activating a magneto relay, which buzzed the exchange operator, who plugged through a connection to the required receiver. In this simple system the circuits on each phone were activated by a local battery. The next advance occurred when a centrally-located battery ran the circuitry of a whole exchange plus the telephone extensions.
From the middle 1920s the galvanised wire was progressively replaced with copper circuitry and manual exchanges gave way to mechanically-operated automatic exchanges along with single and multi-channel 'carrier' systems, which enabled an increasing number of voice channels to be conveyed across the two wires between exchanges and also improved sound quality. PABXs (Private Automatic Branch Exchanges) increased the number of extensions available within a location. The carrier systems converted voice messages between exchanges into high, medium and low frequency signals that were sent across the two lines and then converted back to normal speech at the receiver end. Selective amplification of the signals (i.e. increasing the high and dampening down the low frequencies) ensured that all reached the receiver with equal sound modulation.
Exchange systems gradually evolved from rotary mechanical systems, to step-by-step mechanical systems, then to cross-bar electro-mechanical systems, and finally to the fully electronic digital computer-based system that operates in all central control and remote locations today. Over the same period, telegraph messages through point-to-point teleprinter services were in use, providing hard-copy information throughout the country. This was initially achieved by "patching" the telegraph circuits through at main centres, similarly to manual telephone exchanges. As technology evolved, this process was also automated with the introduction of Telex exchanges that allowed automatic dialling between telegraph centres from the teleprinter. This technology was phased out in the late 1980s with the introduction of fax machines, which are now used throughout Railways.
Electronic train control with the use of computer-based storage has increasingly led to the centralisation of information management, and this in turn has influenced the overall operational functioning and efficiency of the network.
Communications & Train Control
In many of the early rural settlements rail transport preceded the development of roads, so railway stations doubled as post offices and railway staff ran telegraph and postal services as well as trains. For a period after a separate Post & Telegraph (P&T) service was established, that service placed its own transmission lines along railway tracks and both services rented access to each other’s lines. As roads developed P&T moved its poles to more accessible roadside sites and assumed increasing responsibility for its own telecommunication and postal services. Railways continued to advance its separate communication systems with increasing emphasis on the enhancement of train control systems.
As railway traffic increased in scale from the turn of the 20th century, train control objectives advanced beyond punctual running and safety protection to include measures for increasing the operational efficiency of all its resources. The 1926 Railways report to Parliament lists extensive additions that were being made to improve train operation.
By the end of 1932 train control services had been extended to between Ohakune and Marton Junctions and between Oamaru and Balclutha, with an intercall selective system between Balclutha and Invercargill. The main line in the South Island was being worked under train control from Culverden to Invercargill, with control stations at Christchurch and Dunedin. In the North Island the final train control section, Frankton Junction to Ohakune Junction, had been completed so that full train control was in operation between Auckland and Wellington. Interconnections between central and branch operations and between railway and P & T circuits were managed through a series of manual and, increasingly, automatic exchanges. By 1940 Railways alone was running 12 manual and ten automatic exchanges. By the 1960s the whole railway phone system of minor, trunk and automatic exchanges was linked through predominantly its own network infrastructure with high frequency microwave linking, leased from Telecom, between the North and South Islands.
Further advances followed from an initial trial run of 2 MB fibre-optic cable between Paekakariki and Paraparaumu in the early 1980s, the first fibre-optic telecommunications link to be commissioned in New Zealand. Fibre-optic technology improvements reduced cable costs and increased transmission efficiency, until currently 480 high speed channels are available on a 34-MB system over the full length of the North Island Main Trunk line. These have opened up a staggering potential for all aspects of train control and system management. These 'on-line' advancements have been further enhanced by radio and even satellite communication systems.
Radio Communication Systems
The use of radio communications within Railways followed the Second World War, and much of the early equipment, such as the ZC1 ship-to-shore transmitter on Railways' steamer Earnslaw on Lake Wakatipu, was ex-army stock. Increasingly shunting activities have been controlled by hand-held transmitters, reducing the number of staff needed to signal movements with their arms. Developments in this area have now advanced to the stage where a whole driverless train shunting operation can be managed by remote radio-control.
The direct control and management of trains plus the freight they carry have been influenced by advances in radio technology. Over the past five years the 'Alternative Train Crewing' programme has cut staff on freight trains down from three to one, with the loss of the second driver and guard. The single driver maintains contact with Train Control through hill-top repeaters using a VHF transmitter. If the driver has to leave the locomotive, contact is maintained through the loco-based VHF transmitter using a hand-held UHF transmitter. Coded signals from the locomotive and a Global Positioning Satellite system will soon enable central control to locate a train to within 8 metres of its position, stationary or moving. Further advances, utilising electronic barcoding and car-in-motion weighing at strategically placed locations in the national system, will enable train operation to track cargo and manage wagon weight variations from a central control console.
All these advances in communication technology have a constant impact on the administrative infrastructure, as staffing positions are lost and centres of administrative control are relocated from the local station to regional control centre, and now one national control centre.