The Dublin light rail transit system is a modern urban tram system which
runs off an overhead power supply.
The system is divided into two separate lines, Line B (Green Line) and Lines A
and C (Red Line), which connect the city centre with the city’s southern
suburbs and southern/western suburbs respectively.
The contract to construct Dublin’s light rail system, known as LUAS (Gaelic for
“speed”) was managed by the Railway Procurement Agency (RPA), the state agency
responsible for public rail transport systems (tram and metro).
The development of the main infrastructure and technical systems, and the
co-ordination of system integration activities was contracted out to the joint
venture AMB, of which Ansaldo STS is the leader and responsible for the part
relating to the technical systems.
Design activities relating to the infrastructure contract officially began on
20 April 2001. Work on Line B was completed on 15 June 2004, while Lines A and
C were completed on 15 September 2004. It took only three years to complete the
design, construction and commissioning of the two lines covering a total of 25
km, 13 sub-stations, 36 tram stops and the installation of integrated traffic
lights at 54 junctions.
The system was designed in accordance with state-of-the-art security standards,
ensuring, amongst other things, normal operating conditions even in the event
of the failure of a sub-station or central post equipment. In addition, a
back-up system for data received by the remote equipment is provided for
troubleshooting purposes.
The telecommunications systems include the monitoring and control of the
electric sub-stations, the main tram stop systems and depot via system control
and data acquisition (SCADA), a system for monitoring and transmitting data
between the central post and the remote terminal units (along the line, in the
tram stops and sub-stations, in the depot and in some particularly complex
junctions) via a system of fibre optic cables which guarantees high performance
considering the complexity of the system and the required transmission
speed.
Communication between the vehicle and the central post is via radio using the
TETRA digital system. Four radio base units ensure radio coverage on both
lines.
A single central post located near the depot of Line A can monitor and control
the systems of both Lines A and C and Line B. Although the 2 lines are separate
and are not interconnected, there is only one fibre optic system (although it
features a redundant system), which connects Line A and Line B via an
underground conduit which links the two lines near the city centre.
The signalling system is based on the drive-on-sight principle. An automatic
vehicle location system is also provided which, by means of communication loops
installed below the railway track, enables a vehicle to be uniquely identified,
with its position being reported to the central post via a localisation system
installed on board the vehicle. This enables each vehicle to identify whether
it is ahead of or behind schedule and to communicate, based on this
information, its priority at the road junctions equipped with traffic lights,
thereby minimising impact with private traffic and at the same time increasing
commercial speed and level of service.
The system performance is remarkable considering that the journey time of Line
B from the suburbs to the centre is only approx. 24 minutes (compared to the
journey time of 40 minutes by car in the rush hour).
