08.04.08
High Performance Switch System update
The UK’s first all new points operating system for decades has now been in service for over seven years. The first two HPSS systems were installed at Nunhead Junction in October 2000 and over 500 systems have since entered service
HPSS is specified on high value junctions where the heavier UIC60 rail is used but is also approved and utilised on important UIC54 rail junctions. The in-bearer design facilitates mechanical tamping, allowing track formation to be more readily maintained.
Points operating equipment does not merely move the switch rails; it must position them accurately, hold them securely in position for the passage of trains and continuously reports their position status to the signalling system. HPSS keeps a record of its performance in positioning the rails at each operation and these demonstrate a consistency that can be measured to fractions of a millimetre. The HPSS directly and continuously reports the true position of the closed and open rails relative to their respective stock rails. It measures at several positions and can immediately identify if safe limits of position or status are not being met for any reason.
Throughout a number of developments in track turnout engineering, the team at IAD Rail Systems have worked closely with Network Rail to bring the system along in line with these continuously improving rail technologies.
HPSS was designed to be robust with a declared 25 years in-track design life. Starting from this solid foundation, the IAD Rail Systems team have worked hard to drive up performance margins and through this have been successful in increasing both reliability and availability of the system whilst driving down scheduled maintenance requirements.
The inherent low maintenance and high availability design philosophy of the HPSS was recognised by the designers of St Pancras at the London Terminus of the High Speed One line, with the result that the whole of the lead in to the station was specified as HPSS. This somewhat brave decision back in 2001 has been vindicated by the faultless 18 month operation of the Interim Station and now in the subsequent Eurostar International operations. Since the official opening of St Pancras on November 14th there have been no failures of the 36 HPSS systems that control the points from the emergence of trains through the Thames tunnel all the way into the platforms.
All members of the dedicated engineering team at IAD Rail Systems have been working on HPSS since its earliest days and have gained a wealth of knowledge on switch and crossing operation. This team at Weston Super Mare takes pride in its hands-on approach, with everyone holding PTS qualifications and regularly supporting installers and maintainers on track. Experiences and lessons learnt are quickly fed back into product developments which drives up performance and make the user’s life easier. The team not only develops the hardware but also the documentation and training courses for the complete system. Tools, test and diagnostic equipment are also provided by the same team. Technology does not stand still and where significant benefits can be delivered, it is brought in to provide system updates. An example is the new handset which has recently been introduced which provides a greater range of functionality, a better display and a dedicated logging capability. To make signalling design simpler and cheaper, a dedicated power supply has also been developed and approved. This low volume pack is split into three elements for easier portability and fits directly into standard location cabinets. Driving up to six HPSS with only a low current demand on the 110v bus this latest development provides significant advantages in lower cost, shortened design time, reduced real estate requirements and low power demand.
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