metro networks
physical infrastructure actually deployed in the tunnels themselves to an absolute minimum. Most metro systems only shut down for a few hours each night and the scheduling of maintenance or repair work must be fitted into these very narrow windows. A poor decision at the planning stage can have major repercussions further on in the project when the trains start rolling. “Similar issues apply to the siting of larger infrastructure
items in the stations themselves, which are often long and narrow and present their own engineering and environmental challenges. “Finally there are the strategies of what types of antenna or
radiating cables to use and whether different radio systems can be combined on to one cable.”
Security and dependability While the ability to operate reliably in a ‘dirty’ environment – in terms of the physical, acoustic and electrical conditions in a tunnel system – is a major plus factor for TETRA, the vulnerability of Metro systems to accident or terrorist attack is well understood. Some systems have already been built that allow emergency service personnel to use Metro communications in the event of disaster. In the UK, where inquests into the victims of the 2005
London bombings are currently underway, a heavy focus has been placed on the failures of communications systems and the lack of compatible TETRA coverage in the tunnels. Tis made it necessary to manhandle cable into the tunnels so that emergency service workers could communicate at the scene. Te problem was finally fixed in 2009 through an extension of the TETRA-based Airwave public safety network throughout London Underground’s 250 miles of track. Fortunately for the mass of the travelling public around the
world, events like this are extremely rare – and it’s through TETRA’s role in improving both the cost-efficiency and the user experience of Metro systems that the benefits of the technology become most effective and widespread. Robin Davis, chairman of the TETRA Rail Forum and projects director at Actica Consulting, sets the wider scene:
“For quite some time already, TETRA has been the dominant choice for the metro market segment to conduct station– train–control room voice communications. Features such as station call, role-oriented dialling and the newly introduced expedited handover facility have further increased the service levels that TETRA typically offers.”
‘Their eyes widen’ Te drivers out there are already clear. And, for Per Skovsund, sales director at the TETRA specialist Damm Cellular Systems, two different types of migration are involved: “On one hand we have an increasing trend to urbanization across the developing world as populations move towards where the jobs and opportunities are. On the other – at least where some forms of mass transit already exist – there’s a parallel migration from older analogue systems to the digital benefits of TETRA. “In green-field situations, a TETRA system is likely to
be a relatively small part financially when compared to the huge investments involved in building public transport infrastructure. “It’s often the case that potential customers don’t initially
appreciate the entire potential of a TETRA system during first stage discussions – often they’re just looking to replicate the functionality of an older, analogue system. When you do start explaining what can be achieved with data applications – and particularly the impact of these on total cost of ownership through more efficient scheduling or maintenance – then you start to see their eyes widen!
‘
Often, potential customers don’t initially appreciate the entire potential of a TETRA system – often they’re just looking to replicate the functionality of an older, analogue system
’
In Paris, a TETRA system provided by Cassidian helps to move more than five million Metro passengers around the French capital each day. And a secure DigiM@x TETRA network by Thales will this year supersede the Tetrapol network operated in the Paris region by SNCF, the French railway
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