The domain of railway signals and telecommunication | Sunday Observer

The domain of railway signals and telecommunication

17 November, 2019
Railway Trolley Car
Railway Trolley Car

The town of Dematagoda (Colombo 9) in the 1960s and 1970s was predominantly made up of the railway community. The Ceylon Government Railway (CGR) was experiencing consistent growth and massive yards were established at Dematagoda, Maradana and Ratmalana.

A primary concern in train operations is the prevention of train accidents. Rail safety is a more complex operation in comparison to road safety. There are approximately 390 trains that travel around the country. It is vital that train drivers and guards get the correct signals to operate the trains. Likewise it is imperative for motorists and pedestrians to know when a train would be thundering past the level crossing. This is where the Signaling and Telecommunications sub-division of the Railways make a significant contribution to enhance train operations. I made my way to their Head Office, located in the Dematagoda railway yard.

The Chief of Railway Signaling J.I.D.Jayasundara explained, “Railway history shows us that in the infant stages of locomotive operation in England, horses were sent galloping well in advance of the train to update passengers that the train was due. Similarly, in America signalmen were posted as look outs on tall trees adjacent to the rail tracks to observe the approaching train and inform the train stations. The Signals branch in Ceylon’s railway operation was established in the 1970s. Initially, we started with the Semaphore mechanical signals and have today graduated to sending signals via colour lights and fibre optics.”

The domain of the railways exists far and wide. The Signals and Telecommunications branch has two other regional divisions - one at Nawalapitiya and the other at Anuradhapura. The Colombo division remains the heart of the operating network. The branch of almost 500 staff is made up of the Deputy Chief Engineer signal and telecom, Deputy Chief Engineer planning and construction, supervisory managers, Railway signal inspectors, engineers, electricians, signal fitters and signal linesmen. The latter is not to be confused with the railway linesmen who maintain the tracks and are often seen carrying red and green flags during track repairs. The signal linesmen are responsible for taking care of the overhead cables that run between some stations, whereby the railway tablet system is operated. Even to date there is an LTL (line to line) cabin in operation at Maradana manned by 15 staff on a 24 hour basis.

Tablet take-over 

The Tyres Tablet

One of the beautiful memories of our childhood was to see the station master attired in his white uniform, hold the large wooden hoop with raised hand, which is collected by the engine driver as the train passed the platform. Inside the leather pouch is a brass disc - the tablet.

Chief signal engineer Jayasundara explained, “The tablet is a robust and fool proof railway safety operating system. It has served us well for decades, and will do so in the future. It ensures that both, the engine driver and the station master have to concur for the train to approach the next station.”

In 1874, there was a rail accident in Great Britain where 21 people died. A railway engineer named Edward Tyre invented the tablet dispensing system. It makes sure a train has the ‘right of way’ on a single line. The Tyre tablet machine has 3 levels of indicator slides, line closed, train approaching and train on line. On the second slide it displays, fully home, withdrawn halfway and fully withdrawn. Each tablet is engraved with the name of a station. The operator at station A sends a ‘bell code’ to station B. If the line is clear Station B will reply with another bell code. Station A operator will then take the tablet, to be given to the oncoming train. Once the engine driver collects the tablet it is deposited at the forthcoming station and the drill continues through the rail journey. It is impossible for a train to enter a station without the corresponding tablet.

Circuit point repair  

Another interesting view from the train window was to see the Semaphore system at work. The Semaphore is a network of large mechanical arms that act as guiding colour lights to an approaching train. Years ago the signals were painted in red and blue - not green. The simple science behind this was that at night - the yellow glow from the oil lamp behind the signal manifested the blue glass as a green signal. Today, these Semaphore signals are made at the base workshop in Dematagoda. At present red and green luminous stickers are pasted, which can be picked up by the train’s powerful head light. Over the past few years the signals sub division has worked hard to upgrade some sections of train line with electric colour light systems. These can be spotted from Colombo to Rambukkana, Beliatta to Colombo, Ragama to Negombo, Anuradhapura to Kankesanthurai and Medawachchiya to Talaimannar. The mechanical Semaphore signal is in operation from Rambukkana to Badulla and Matale, from Mahawa to Trincomalee and Batticaloa also extending from Polgahawela to Anuradhapura. This large network of wires, circuits and signal points requires routine maintenance. The systems rely on electricity. In the event of a power failure the railway circuits have enough standby battery for 2 days, supplemented by generators. Signal work crews are deployed in every operating region to cover 5 stations a week. They travel on special railway trolley cars (on the tracks) to inspect and repair. At any given time trains travelling across the island can pass by 1 of 175 control stations. The signals sub division has to ensure the safety of all moving trains. Another safety element is the Inter-Locking system. The chief of signals elaborated, “The primary aim of inter-locking is to prevent train accidents at common diverging points. The signals and point mechanisms are locked together. At every 800 metre interval on the track we have a safety circuit”.

Explaining further on the new innovations in railway signaling and telecommunication, he added, “We are proud to have upgraded the signal system from Polgahawela to Kurunegala an extent of 23 kilometres. This project was planned, designed and installed by our own team. It is 90% complete at present. We also have plans to upgrade verbal communication between trains and main stations. We hope to enhance the PABX at Maradana control division and also introduce new mobile radio system for the train engine driver.” Signals and Telecommunication sub-division will continue to upgrade and enhance their contribution to Sri Lanka Railways.