Standing here on the platforms of the electrified York station, breathing in a fog of diesel fumes from five diesel trains awaiting departure, it is easy to wonder what went wrong. Indeed, the East Coast main line (ECML) proved that the UK could deliver rail electrification efficiently, with 2,250 single-track kilometres electrified for £671 million (adjusted for 2018) (issue 158, December 2017). The programme took seven years from authorisation to completion and was just eight weeks late compared to the original schedule.

As a result, passengers enjoyed faster, cleaner, quieter and more reliable electric train services and passenger revenues increased by 30 per cent; rolling stock procurement and maintenance costs were significantly reduced; track maintenance costs were cut as lightweight electric trains replaced heavy diesels – and fuel costs fell too.

The industry had demonstrated an ability to safely and successfully deliver efficient electrification. It had a proven, rapid financial case and the teams were well-practiced.

So why, twenty years later, am I standing in a haze of diesel?

In fact, the industry delivered further commuter electrification in Birmingham and Leeds before falling silent in 1995. This happened two years after the Railways Act entered law, which required co-operation between the train operating companies (TOCs) and Railtrack for track access. The TOCs stood to gain the most from electrification, but all of the infrastructure plans were developed by Railtrack, which incurred the costs. And, with franchises similar in length to electrification projects, only truly outstanding business cases like GNER’s Electric Horseshoe (Leeds-Hambleton Junction electrification) were developed.

The climate was also quite different at that time, with environmental concerns yet to become mainstream and oil prices being still (relatively) modest. Against this background, it was faster and easier in the new structure to buy bigger, more powerful diesels, despite the fact this would only drive cost increases in the long term.

Lessons learned

First and foremost, the railway is a system. No engineering discipline can be considered in isolation, and neither can the business case. Successful electrification is designed as a system. A decision as innocuous as the choice of supply locations affects everything from route operability (business case) to the number, location, size and temperature of required OLE conductors, which in turn affects everything from tension lengths and maintenance costs to height and strength of structures; which in turn affects visual impact and overturning moment of structures; which in turn affects numbers of structures, pile lengths and installation rates achievable with construction trains. A butterfly effect of impacts from seemingly unrelated disciplines.

From development of capacity and journey time improvements to the procurement of electrification and rolling stock, costs and impacts must be considered as a single system. It is cheaper to make compromises at the design stage than adapt infrastructure to train, or vice-versa.

Secondly, project teams must be free, in practice, to implement the most pragmatic, efficient solutions that suit the route and operators in question. The ECML electrification was delivered by an integrated multi-disciplinary team that established close working relationships with the train operators and route. Decisions lay largely in the hands of the people who were responsible for the cost, schedule and disruption of the work. The highly prescriptive and technology-specific nature of current standards, developed separately from the delivery and customer teams, is perhaps the biggest constraint facing UK electrification designers.

Thirdly, we must be willing to learn from best practice. The ECML electrification was not an experiment, it was an evolution of proven system designs. With decision-makers accountable for delivery, projects were not used to experiment with wholly new designs, and standards were not changed repeatedly during design. The lessons of previous schemes were learned. Given sufficient time and money, any system can be made to work once, but more complex or difficult to install ideas were not repeated. Importantly, the UK did not have to fund all the learning – successful innovations from across Europe were incorporated and, in turn, the UK exported its own innovations.

What has changed?

The fundamentals of rail electrification still hold true and electrified railways are cheaper by all measures. Electric rolling stock is cheaper to buy, maintain and fuel, overall public performance measure (PPM) is markedly improved, journey times fall and track maintenance costs are reduced. The economics in the 1981 DfT/British Rail Review of Mainline Electrification have improved with rising traffic volumes and, given efficient installation, the business case is stronger than ever.

Other factors were not considered in 1981 – the government placed no value on pollution (and UK electricity then was 40 per cent coal fired and just two per cent renewable). Environmental protection is now government policy – by 2020, UK electricity will be 40 per cent renewable and zero per cent coal. Electric railways are trending towards, not just zero-emission at the point of use, but zero-carbon fuel overall. They are the only credible clean, green option for mass transit.

With a more intensively operated network, route capacity is becoming of greater significance. On mixed-traffic railways, electrification delivers capacity and PPM benefits, accelerating faster from stations and climbing hills more quickly. Sadly, such benefits are not captured in business cases reliant on journey time analysis of a single, unconstrained express train, but, when simulating an entire train service, the benefits are clear.

The economics of electric rail are stronger than ever, and railways across Europe continue their steady, rolling electrification programmes of typically a few hundred track-kilometres per year. Yet today, on the Great Western main line (GWML), electrification is being de-scoped and electric trains fitted with diesel engines. Rail Engineer reported in November 2017 (issue 157) that the electrification cost had risen to seven times the ECML cost per track kilometre and, with the programme running several years late, it is delivering at half the ECML speed. In fact, the warning signs of cost escalation have been with us since the West Coast Route Modernisation.

Capital costs in the UK must be brought back closer to international norms if electric railways are to continue to have a standalone business case, with technology changes offering the opportunity both for reduced costs and improved benefits.

New power for trains

Echoing changes in road transport, new energy storage vectors, such as hydrogen and battery, are creating new possibilities for rail. Although hydrogen trains produce no harmful emissions themselves, CO2 and other pollution is released today in the production of hydrogen from petrochemicals, (although still cleaner than diesel). However, production from electrolysis of water is possible, which makes hydrogen another means for carrying electrical energy from a generator to a train, where it can be returned to electricity in a fuel cell.

With electrolysis, hydrogen trains require around three times the electrical energy of an electric train for each kilometre travelled. This is due to the energy losses of this cycle, including the energy required to compress hydrogen to very high pressures for storage. Hydrogen stored at 350 bar has only one seventh of the volumetric energy density of diesel and this, combined with its lower energy efficiency than electrification, means it is not a suitable fuel for high-power or long range applications. However, while hydrogen is unlikely to change the economics of the mainline railway, it may offer a new option for rural and remote lines.

Battery electric cars and buses, however, have reached the tipping point where they are competing on whole-life cost with oil-based fuels, and the pace of development is such that battery EMUs (BEMUs) will undoubtedly play a significant role in UK rail. Working with Sheffield University, Siemens Mobility has been studying the potential of battery trains in the UK for two years, understanding their strengths and weaknesses and the implications for power supplies. BEMU diagrams require sufficient time under the wires (or charging points) to recharge, but, with the electrification of primary route sections (intensively trafficked or high-speed routes), larger areas of secondary non-electrified routes are opened up for BEMU operation.

BEMUs act as a benefit multiplier. Most benefits of electrification scale with the number of diesel trains that can be replaced with faster, cheaper EMUs. On a route like TransPennine, core electrification from Manchester to York enables express electric trains to accelerate faster from speed restrictions and reach their maximum speeds on the steep inclines. But many service groups extend across non-electrified secondary lines, preventing pure EMU operation. While diesel bi-modes allow journey-time savings, bi-modes lose major cost reductions of electrification (cheaper train procurement, train maintenance and track maintenance). Worse still, while secondary and rural routes remain non-electrified, diesel trains continue to constrain capacity and performance where they join congested primary route sections.

BEMUs enable the benefits of the core electrification to be felt over a much wider area. For example, electrification of the core route section Manchester-Selby/York enables BEMU operation of a long list of extension routes as varied as the complete Transpennine Express network (Windermere/Blackpool/Liverpool-Scarborough/Middlesbrough/Hull) to city commuter networks such as the Calderdale line and Harrogate loop, delivering most of the benefits of an electric railway.

In this way, BEMUs can bring shorter journey times, zero-emission at point of use, cheaper train procurement, cheaper train and track maintenance (albeit not as cheap as pure EMUs) to a long list of communities unlikely to see route-wide electrification. The introduction of electric performance on secondary services helps them clear congested route sections more quickly, improving route capacity, while the reduction in diesel traction improves train performance on routes where a PPM boost is sorely needed.

Battery trains are not new, Robert Davison built the first battery train in 1839. Siemens introduced a battery/electric locomotive charging from OLE in 1929 and British Rail operated a BEMU on the Deeside railway from 1958, charged manually after each journey. It is the rapid improvements in cost, energy density and power management (improving control of charge, discharge and therefore lifespan) over the past decade that has made them a disruptive technology.

The future of electrification

Electrification is being delivered today across Europe at a fraction of recent UK costs. Designers there have the freedom to design the whole system to meet the output requirement most efficiently, combining designs proven elsewhere to keep development cost and risk low, with evolutionary, incremental improvements developed between schemes.

Efficient design and installation

An example of this controlled evolution is the Denmark electrification programme. With a ten-year rolling programme and freedom to design, Siemens was able to plan for and deliver highly efficient electrification, avoiding the stop-start workload seen in the UK. Freedom to design allowed proven efficient designs to be combined – for example, Sicat OLE (pictured left) could be used, benefitting from decades of installation experience and continuous improvement, with minimal enforced redesign. This freed effort to focus on those unique features that offered the most benefit. For example, the constrained structure gauge in many locations would have normally required reconstruction. However, Siemens was able to develop a railway-specific surge arrestor that reduced the electrical clearance required and avoided reconstruction of many structures, drawing on proven surge-arrestor technology delivered in other industries.

There are promising signs of individual improvements. For example, it was recently reported that Network Rail plans to combine proven technologies to reduce structure reconstruction cost – using railway surge arrestors (developed by Siemens for Denmark electrification, but previously used in other industries), insulated paint (introduced by Network Rail for the LNE route in 2016, but previously used in other industries), and compact insulated underbridge arms (with origins in British Rail Research in the 1970s/80s).

Modern power supply design

Traction power connections in 25kV railways have, until recently, been made directly to the electricity supply network through simple transformers, resulting in complex harmonic and phase sequence challenges. As traction loads have grown and electricity supply continues to decarbonise, connection at 275kV or 400kV has become necessary, restricting the number of feasible supply locations and constraining all subsequent design. Neutral sections required between supply areas prevent energy-efficient parallel feeding. By contrast, 15kV railways use power converters – initially, maintenance-intensive rotating machines, then by the 1980s semiconductor technology began to replace these and, today, modular multilevel converters use the same components and design principals as modern power conversion in the electricity supply industry, motor drives and renewable generators.

The use of static frequency convertors (SFCs) pictured above has enabled Siemens Mobility to halve the cost of major electrification works compared to the original standard UK design. However, the benefits are not limited to reduction in cost. The elimination of additional OLE conductors and lineside transformers simplifies OLE construction, reducing both the required track access and visual impact. The controllable output voltage improves acceleration and journey time compared to historic supply technology, and, crucially, supply capacity can be added incrementally as required, where it is required.

Perhaps the most exciting advance lies in OLE safety and reliability. The energy released in a typical short-circuit fault (up to 60MJ) can lead to de-wirement and, sadly, each year a number of trespassers suffer electric shock. SFCs limit the maximum fault current, and the combination of simple, fully sectioned protection with Siemens Mobility’s Sitras Plus FastSafe technology enables more reliable detection and faster clearance of the highest consequence short circuits. Disconnecting current up to 40 times faster than historic systems greatly reduces the likelihood of de-wirement and provides a step improvement in safety.

Is it enough?

Bringing costs back towards international norms is a big shift, and it will take more than individual improvements to achieve. The UK railway network is intensively utilised with few diversionary routes, track access is expensive and the pause in electrification during the 2000s means there is limited practical experience in the industry. Yet this intensity of traffic means that the financial case for electrification should be stronger in the UK than anywhere else in Europe, given similar costs. The availability of battery EMUs improves this further.

There are signs of hope in future projects, where alliances with multidisciplinary design have been brought together under common incentives, with some degree of ability to influence the design at the option selection stage.

However, the tendency to impose critical design decisions prior to the start of the design, and the quantity of highly prescriptive standards, continue to constrain the ability to bring costs down to international norms. Too often, the expectation is that proven equipment should be re-engineered to suit UK preferences, diluting the benefit of decades of experience and continuous improvement.

To truly demonstrate efficient delivery, a demonstration project is required that is not subject to these constraints. With a simple output specification, and a single organisation accountable for all safety, cost, and delivery, but otherwise free to undertake whole-system design, electrification is possible in the UK at a fraction of the cost of recent experience.

And, at efficient prices, the business case for increased electrification of UK rail is the strongest it has ever been.

Written by Richard Ollerenshaw, engineering manager (innovation) at Siemens Mobility rail electrification.


Read more: Rail Engineer December 2018: Electrification focus