TETRA – taking care of metro transport

Travel on a metro, underground network, take the subway, the MRT (mass rapid transit) train – however you choose to describe the transport, chances are that you will be travelling in the company of TETRA communications. Millions of people are, every day.

TETRA (Terrestrial Trunked Radio) technology is used throughout the world to deliver secure, reliable and robust critical communications. As well as being the public safety technology of choice for governments around the globe looking to protect their citizens, TETRA is used by an increasing number of commercial and industrial sectors. These include transportation and travel: airport, rail, metro, and taxi organisations; utilities, oil, gas and petro – chemical industries; commerce, retail and leisure; and major sporting events such as the Olympic Games.

TETRA was born in the 1990s when the professional mobile radio (PMR) community came together to write a standard to meet the requirements of public safety users, other professional users, operators, spectrum regulators, manufacturers and others involved in the implementation of critical communications. The standard has been enhanced to meet the needs of the new data communications world and remains the technology of choice for mission critical communications.

After public safety, the largest users of TETRA are those in the transportation sector. Mobile digital radio is dominant in today’s transport systems, and TETRA is the most implemented technology. Metro operators have adopted TETRA as the communications system of choice for networks around the world for both voice and data services.

TETRA delivers flexible, efficient and structured communications, some of the reasons why it is chosen by so many metro operators. Robust and reliable communications between drivers and line controllers are essential for safe operation of the transport system, and instant group call capability is necessary for the smooth running of stations and depots, and for track maintenance.

The train driver and onboard staff need to communicate with station staff, and control centres. Telemetry is used to monitor train health, for safety reporting such as ‘doors open/doors closed’ information, reporting locations and conveying ‘next train’ information to platform displays. In addition, TETRA may also be used for more bandwidth intensive data such as on-train and platform video surveillance images for real-time security measures.

TETRA is also used to keep passengers informed – passenger information and public address systems provide on-board information by displaying messages from the network control centre, and can be updated in real-time. Passengers also need the assurance of real-time information in emergency situations, or during a major event when schedules are disrupted.

As train systems become more complex, with driverless systems and more-and-more processes controlled by technology, communications systems become critical to the safe and efficient operation of metro services. Transport systems will require greater breadth and depth of information delivered in real-time in order to operate efficiently. This is why an increasing number of operators are turning to TETRA for an integrated voice and data solution to address enhanced requirements.

In Europe, metro systems using TETRA include the Copenhagen Metro in Denmark, Madrid’s metro in Spain and the UK’s London Underground network.

Copenhagen’s Mini Metro was one of the earliest TETRA contracts, won by Motorola. The metro has two lines over 21km of track, and runs 34 driverless trains co-coordinated by a single control and maintenance centre. The metro is a 24-hour automated people mover, with all equipment remotely controlled. This enables operational staff to concentrate on assisting passengers in order to ensure a friendly and secure atmosphere and to discourage vandalism. Operational staff (stewards) can move freely on the trains and in the stations, answering passenger queries, checking tickets, and assisting in emergencies.

Security is further enhanced by communications through which passengers and stewards can ask for assistance, be informed and be seen from the Control Centre while on a train or at a station. The trains run on a fully automated system based on ATC (Automatic Train Control), which constantly monitors where every train is positioned. This gives the metro a high degree of safety, and ensures that at least 98% of the trains will be running on time.

In Spain’s capital city of Madrid, the multi million population relies on efficient public transport – and the Madrid Metro is the second largest metro network in Europe after London. TETRA delivers an integrated voice and data communications solution to help deliver more effective public transportation services, with Dispatcher driven group call communication, simple text based services for messaging, and the ability to make private individual calls and calls interconnecting through the GSM and fixed line telephone networks.

The TETRA terminals are designed for use in trains, and are fitted in specially designed consoles – there are also purpose-designed holders and chargers for portable terminals. As data applications develop, the TETRA system has capacity for expansion to carry future data-based services.

Dating back to 1863, the London Underground is the oldest underground railway in the world and carries more than a billion passengers a year. There are 275 stations, 125 of which are sub-surface. There are 249 miles of track, of which 112 are in tunnels, and 700 trains. TETRA technology enables voice communications between train drivers, line controllers, signaling operators, depot staff, dispatchers and station and maintenance staff. The network transmits alarms and status messages, and text messaging to train drivers.

The London Underground TETRA network is known as Airwave, and its arrival meant that British Transport Police officers no longer have to carry two radios. It is also the first time a radio system can be used underground by both Metropolitan Police Service and City of London Police officers.

Officers can now communicate with colleagues above and below ground. This has an impact on the general public and emergency services can now respond quickly and effectively to any incident or event to ensure greater public safety. The police are already realising operational benefits particularly at high profile policing events such as the annual Notting Hill Carnival, New Year’s Eve and regular football matches.

Officer safety has been improved as demonstrated by the 30+ ‘emergency messages’ sent each month over Airwave from officers whilst working underground. In the first month of use by London Ambulance, the service reported how a first responder was able to summon specialist equipment to be brought to a patient enabling rapid transfer to hospital about 15 minutes faster than if the Airwave TETRA network had not been available.

About the Author

Phil Kidner

Phil Kidner is CEO of the TETRA Association, which represents a membership of 150 organisations around the world. Phil’s main responsibility is to promote the TETRA standard and its benefits of security, resilience and interoperability, and manage its evolution to ensure the needs of all users are met. As the communications world converges, Phil is building and strengthening relationships with industry organisations and user groups across the world to help drive the TETRA market forward.