With much of the UK rail network featuring low density lines – characterised by an asset base which dates back to the 1940s and which is increasingly expensive to support and maintain – Network Rail recognised the need for a new approach to the re-signalling of rural lines with the objective of reducing both installation and ownership costs.

Responding to this, in the last five years the concept of modular signalling has been developed by Siemens Rail Automation (formerly Invensys Rail), working in close partnership with Network Rail. The development programme recognised two key factors: firstly, that there were at best only marginal business case benefits to be made from upgrading secondary lines to computer-based interlocking technology and secondly, that the resources and skills required to operate legacy systems were no longer providing value for money.

Rural upgrades

The modular signalling concept offers Network Rail the opportunity to upgrade these rural lines cost-effectively, using proven technologies and provides a positive economic case for investment in secondary lines. This solution also delivers forward compatibility with future technology, including the European Train Control System (ETCS).

Siemens’ modular signalling solution includes products and technologies from across the company’s Rail Automation group, with therapid deployment mini pile foundation being verified prior to installation of OC grillage copy [online] system being based primarily on simplicity of design and ease and repeatability of the installation process. Essentially the company’s development team examined every part of a signalling scheme to identify where different products and new processes could be introduced to provide operational and cost benefits.

At the heart of its modular signalling solution is Siemens’ Trackguard WESTRACE computer-based interlocking, enabling signalling schemes to be delivered from just a small range of core components. From this range, the company has developed a limited number of configurations to suit the precise requirements of low density rural lines, the products providing a number of standard signalling systems and a set of standard data templates.

Using standard templates means that the number of engineering hours required for any given scheme is significantly reduced and importantly, that the validation and verification process is much faster and more straightforward, such that systems can now be tested off-site at Siemens’ purpose- designed hangar facility in Chippenham.

Modular signalling has also been developed to operate via Network Rail’s Fixed Telecommunications Network (FTN). By using internet protocols (IPs) over the ethernet, the system can connect to Network Rail’s control architecture, meaning that fewer signallers are able to control greater areas (so reducing operator costs).

The result is a future-proof system, developed specifically for low-density rural lines which delivers reduced material costs, rapid and low-cost installation and much reduced cost of maintenance.

Representative pilot

The Crewe – Shrewsbury Modular Signalling Pilot Programme was successfully commissioned by Siemens over the weekend of 12 – 14 October, with control of the line now being undertaken from the Network Rail Regional Operating Control Centre in Cardiff.

The pilot programme contained many of the application scenarios required to prove the generic solution – and nearly all the configurable scenarios with which most rural or secondary routes can be re-signalled – and covered 30 miles of bi-directional signalling; seven level crossings – five of which have now been converted to manually controlled barriers with obstacle detection (MCB-ODs) – and two complex fringes.

Siemens installation work began on site in March 2011, with a Siemens Trackguard WESTRACE Mk2 interlocking at the heart of the scheme – which also features object controllers, plug coupled cables, axle counters and lightweight signals. The trial of the train detection equipment began in July 2011, with extensive testing of the programme continuing through 2012 and 2013 and the pilot scheme proving the case for the design work, validation and verification, installation and operational effectiveness of the system.

By its very nature, modular signalling uses less trackside infrastructure than a conventional application of computer-based interlocking technology, the small core range of components making the optimisation of equipment positioning to overcome input/ output limitations all the more critical.

Significant development

Commenting on the programme, Siemens regional delivery director, Rob Cairns said: “With the rising cost of signalling renewals and the recent Office of Rail Regulation efficiency determination, experienced during Network Rail’s Control Period 4, the business case becomes ever more attractive for technologies which reduce both capital and operating costs.

As a consequence, an increasing amount of future project investment is being proposed for modular solutions and we are seeing schemes which make use of hybrid technologies (a combination of modular and conventional systems) in specific areas on more complex primary routes.

Fitting backboard to new gantry at Shrewsbury fringe reading towards crewe [online]“The price of signalling has been steadily increasing over a number of years, as suppliers have seen their cost bases continually rising to reflect not only the specification of conventional signalling, but also the infrastructure associated with it. Our own data shows that around 50% of our cost base has been associated with the additional steelwork and copper located trackside associated with the signalling, or the large scale plant and concrete to get it there and keep it there.

“Signalling pricing also reflects the lengthy design processes associated with conventional technology, as often there are a number of bespoke or non- repeatable signalled scenarios which have to be individually designed and tested. The cost base of the design itself is not an influencing factor, it does however drive the overall lead-in duration for signalling investment – and time becomes cost on the balance sheet.

“Modular Signalling is arguably the most significant development in the signalling market since the introduction of solid state interlockings in the 1980s and this technology shift becomes increasingly important as more and more schemes rely upon the modular approach in Network Rail’s Control Period 5.

“Our technology is now established, and proven – we also know how to effectively apply it. Modular by its very nature is targeted at a fixed number of operational signalled scenarios, flexing modular around complex layouts will never pay dividends, because whilst the technology is very adaptable, we would not be using the technology in a way where its value could be realised.

“By working with Network Rail and its customers, I am confident we can improve the modular proposition even further by optimising operational configuration, and establishing rules which allow the investment to be weighted against the available benefits in a way where the customer decides!”