feature
High speed turnout using a Hy-Drive
New Dorman LED southbound signals and axle counter EAK units ('mushrooms') at Tamworth. assembly – in bearer clamplock and SO
The nearest signal is for bi-directional operation of the Down Fast on its left. backdrive - Lichfield North Jcn.
with most modern remodelling schemes, project at the 103½ mile post where they signals. The position light route indicators
the interfaces between these disciplines abut Atherstone I/L, part of the Nuneaton and 'theatre' route indicators are also
touch virtually all others, in what has re-signalling project, also commissioned LED types. In general, the signals are
become a very complex systems during the blockade. mounted on Crown Posts suspended
orientated railway. Bi-directional running has been provided from four track gantries, with a small
Principal Project Engineer Tony Davis on the Down Fast and the Up Fast lines number on straight post structures. As a
and Principal Project Manager Paul south of Lichfield North Junction through result the signals are as close to the
Yendell have been co-located with the to Amington Junction to allow additional driver's eye level as possible. The Project
Network Rail Project Team on site during flexibility during future maintenance and has installed substantial gantries to
the works, supporting co-ordination renewal works or during a failure. This overcome any movement in high wind
between the different disciplines, both facility will not be commissioned until a and the Crown Posts allow for winding
internally to SSL and externally with other later date. However, the signals are all up the signal head into suspended cages
contractors. In hub and spoke contracts, it provided, tested and fixed at red until for maintenance without placing staff at
is essential that no items fall between that time. North of Lichfield the lines risk or requiring extensive possessions.
contractual boundaries and that the remain uni-directional at present, AzLM axle counters have been provided
various construction elements all come although provision has been made to throughout the re-signalled area with
together correctly. The role of Paul's team facilitate possible future changes. new Pentium Evaluators situated in Relay
has been to work as part of the TV4 Minor alterations were required at Rooms where they interface to the SSI
Integrated Project Team to achieve this. Lichfield Trent Valley Jcn signalbox to interlockings. As with other areas of the
provide a new fringe to Rugby SCC. The WCML, the axle counter heads are
New infrastructure connecting chord between the Wichnor overlapped on crossovers so that a
The new signalling control system uses Junction to Birmingham line and the failure of one section only affects one
SSI technology, designed in Derby by SSL WCML is now track circuit block operated, line, again increasing availability and
under the guidance of Simon Henson from with Rugby having a slot on the signal overall system reliability. Twisted 10 pair
an approved signalling scheme plan protecting the branch. lineside cables are provided throughout
developed by Network Rail. Rugby Signal the interlocking areas to enable the EAKs
Control Centre (SCC) houses 6 new SSI Safety lockout system ('mushrooms') to talk to the evaluators
cubicles to control the Trent Valley area, To provide safe access for railway staff and for DC power to be supplied in the
horizontally split into three for the Down entering the infrastructure for patrolling other direction. Two pair cables are used
and three for the Up directions. From a or other activities, the scheme plan from the lineside locations to the EAK,
control perspective, this effectively provides for a safety lockout system each EAK also being bonded to the
creates two side by side railways, throughout the re-signalled area. The traction rail to eliminate touch potential
providing diversity in case of system system is operated by a number of problems.
failure. lockout switches known as LOD(T)s, the Point machines are a mixture of HPSA
The project's northern interface is at the 'T' referring to multiple access points, machines with powerlink back drive
121¾ mile post where LICHFDDN and using non captive keys, allowing access system and in-bearer clamp lock
LICHFDUP SSIs interface with Rugeley and egress at different places. machines fitted with SO backdrives, an
interlocking, an existing electro- Occupation of a section requires co- Alstom product supplied to the UK rail
mechanical relay interlocking controlled operation with the signaller, who industry through SSL. The longer turnouts
by Stoke on Trent SCC. TAMWTHUP and provides the release from Rugby, in a are driven using the SO assemblies
TAMWTHDN SSI control the signalling from similar way to an old fashioned ground because of the limits of using the
just south of Lichfield station. POLWTHDN frame release. powerlink back drive on very long
and POLWTHUP SSIs complete the six and All existing signals, most of which switches. Both types of machine have
control from just south of Tamworth dated back to the 1960s, have been been developed to cater easily with the
station to the southern fringe of the replaced with modern Dorman LED increased line speed of 125mph.
26 | the rail engineer | october 2008
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