In many ways, Britain’s railways face an uncertain future. One certainty, however, is that with the changing climate railways must adapt to new extreme weather patterns if they are to continue to operate a safe and reliable service.
The recent seminar ‘Adapting Railways for a Sustainable Future’ held by the Railway Division of the Institution of Mechanical Engineers (IMechE) was therefore timely. After considering the overall requirements for sustainability, this event considered railway operations in all seasons, energy and waste reduction, and how electrical traction demand could be smoothed. As we report, this was an interesting event.
The overview was provided by RSSB’s director of sustainable development, George Davies, who outlined the industry’s Sustainable Rail Blueprint (SRB). He advised that the SRB, which was published in November, is now moving to implementation. It has 11 topics which support three sustainability aspects as follows:
- Emissions: Net zero carbon rail; Clean air; A quieter railway.
- Natural Environment: Preparing for a changing climate; A railway for nature; Zero waste; Protect & conserve water.
- Social Sustainability: Maximising social value; Rail at the heart of communities; Careers, economy, and sustainable growth; People centred rail.
The SRB provides a road map showing how the strategic aim for each topic can be achieved. It also provides six common solutions which are key enablers cutting across the SRB topics. These are: Zero emission traction; Seamless journeys; Nature-based solutions; Social value; Data framework; and a Culture for Sustainability.
Professor John Dora of Climate Sense noted that in the five years up to 2029, the rail industry planned to spend £2.8 billion in climate change adaptation which is the subject of ISO 14090:2019 ‘Adaptation to climate change – principles, requirements and guidelines.’ There is therefore a need for effective management and competence to ensure compliance with this standard.
To achieve this, he described an RSSB-funded project to develop a climate change adaptation maturity matrix which can be used to assess adaptive capacity across the UK rail sector and provide organisation-specific action plans.
A railway for all seasons
The next six presentations covered planning and mitigation of different extreme seasonal weather hazards. Brian Haddock, Network Rail (NR)’s head of seasonal and weather resilience, set the scene with a presentation on planning for extreme adverse weather. His presentation described the available meteorological tools, risk-based planning, and how weather action plans are communicated as described in our feature ‘Responding to Scotland’s weather’ in Issue 206 (Jan-Feb 2024).
The importance of railway water management and how this is supported by a catchment analysis was the topic of a presentation by Mona Sihota, NR’s technical head, drainage and lineside. This role was created in 2015 and its importance was tragically highlighted by the Carmont derailment. This led to the development of NR’s Water Management Strategy in collaboration with the Environment Agency. This shows how NR now considers drainage to be a whole system of assets that manage water between it coming onto and leaving NR’s infrastructure. It also requires NR to be a good neighbour that works with adjacent landowners to mitigate flooding onto the railway and avoid flooding adjacent land.
An important aspect of this strategy is its catchment analysis which considers, amongst other things, the peak flow, slope, and land use for 100,000 individual surface catchments to determine the threat they present. Catchment polygons, coloured according to threat, will then be displayed on NR’s GeoRINM viewer to provide a better understanding of flooding risk, and improve the management of drainage assets.
Low adhesion during the autumn leaf season is a well-known hazard covered by many articles in Rail Engineer. One solution, high pressure water abrasive suspension, was described by Tanya Ball of LNT Solutions Ltd. She described how a project to evaluate this system was being sponsored by NR’s performance innovation fund. To do so it had been fitted to a Class 153 unit and tested for two weeks on the heritage East Lancashire Railway.
To test the system, three layers of leaves were applied to a clean rail head at various test sites and then rolled over by a diesel locomotive. This reduced the coefficient of friction from typically 0.16 to 0.04. After one test cleaning pass at 60 mph, it was then found to have increased to 0.14. There are now plans to trial this system in autumn out of Exeter and on the Fife circle in Scotland.
Managing the vegetation that causes this adhesion problem will become more challenging as increasing average temperatures extend the growing season. Vegetation can also cause significant sighting problems and present risk to overhead line electrification equipment. In her presentation, Cordel’s development director, Rebeka Sellick, explained the benefits of Artificial Intelligence (AI) to analyse lineside vegetation growth information captured by train-mounted LiDAR equipment.
She explained why this is a cost-effective approach which can rapidly identify the types of risk presented by vegetation, assess the amount of vegetation to be removed, detect trends, and quickly provide useful information for maintainers on map-based displays.
The summer risk of track buckling was considered by the University of Southampton’s Professor William Powrie. He noted how 2022 saw many locations break their highest temperature record by 3°C with a new UK record at Coningsby of 40.3°C. As rail temperatures can be over 50°C when the air temperature is 37°C, this is a significant problem.
Rails are laid with a stress-free temperature (SFT) of 27°C, however this can vary along the track. As UK annual temperatures increase so does the potential for rail buckling. Professor Powrie’s research modelled rail buckling temperatures and the factors that need to be managed to reduce this risk i.e. rail and sleeper type, track irregularities, and ballast condition. It also showed the extent to which reducing train speed reduces buckling risk, though such mitigation should be a last resort.
Cooling the tube
The London tube is not exposed to the weather and does not have the vegetation issues faced by the main line railway. However, compared with modern metros, it has diminutive tunnels which must dissipate a lot of heat from brakes, motors, and passengers.
In the early days of the tube, the temperature in the tunnels was 14°C which is that of the London clay through which they were bored. Indeed, the way that the tube offered a relief from the hot sun above was promoted in early adverts. However, over more than a hundred years, the temperature of the clay around the tunnels has increased and tube air temperatures can reach an uncomfortable 30°C. This also reduces the efficiency and reliability of trains and equipment. With planned increases in service frequency, tube temperature has become an urgent problem especially as the platform air handling units used to cool stations are prone to blockages due to dust and dirt in the tunnels.
In their presentation, TfL’s Anthony Ridley and Emil Tschepp described the development of more reliable station cooling systems funded by Innovate UK. This changes the orientation of the cooling coil to remove the risk of blockage. After testing a full-size prototype, this was installed above a disused platform at Holborn. This validated the concept and achieved a cooling output of 12kW/metre though it highlighted issues with condensation and water flow rate sensors.
As a result, the design has been developed to use a more efficient aluminium extrusion profile, incorporating a drip guard, to work with axial fans and increase the number of panel layers from two to three. This is expected to increase cooling performance from 12 to 26 kW/m with between four and eight units per platform needed. The intention is to install these cooling systems as part of the Piccadilly line upgrade which will see an increased service frequency with the introduction of its new trains.
Reducing emissions and waste
Richard Thorp, HS1’s director of engineering & technology, presented his company’s strategy to deliver net zero. Currently, HS1’s annual energy consumption is 213GWh of electricity and 8GWh of gas which results in direct emissions of 46,400 tonnes CO2E per annum. He noted that these emissions were much less than the 750,000 tonnes CO2E per annum that could be saved by modal shift from flights and cars onto HS1.
HS1’s plans to eliminate both direct (Scope 1) and indirect (Scope 2) emissions include procuring net-zero electricity via a private wire and the replacement of boilers with heat pumps at St Pancras, Stratford, and Ebbsfleet. Richard considered that these plans were robust though he advised that a strategy to reduce Scope 3 emissions from HS1’s supply chain had yet to be developed.
He concluded by pointing out that effective carbon reduction plans require a balanced portfolio of large and small schemes and that energy reduction schemes come with a positive business case.
Finding the right solution to decarbonise rail vehicles was the subject of a presentation by Ian Robinson, Alstom’s platform engineering manager. Ian pointed out the benefits of modifying existing fleets with sufficient residual life as this required less embodied carbon. However, he also highlighted the challenges of such modifications in respect of space and weight constraints as well as systems integration with existing equipment and train control systems.
He described two case studies. The first was the SNCF AGC fleet which are diesel electric multiple units that operate on electrified and short unelectrified sections and have engines that do not meet the latest emissions standard. Five of these were modified to become Battery Electric Multiple Units (BEMU) by removing the underframe diesel engine and its roof mounted cooler group and fitting batteries with a thermal conditioning unit. Network testing of these units is to start this year.
The other case study concerned an Australian VLocity diesel multiple unit (DMU) that also had an engine that did not meet latest emission standards and for which there was a target to reduce fuel consumption and emissions by 25%. With no electrification in Australia, the solution was an engine and transmission upgrade and intelligent engine management.
Colin Musisi, a development engineer with Porterbrook Leasing described how rolling stock could be modified to make it more resilient to climate change and more comfortable for passengers. Such modifications were necessary as those who wrote standards before 2000 did not foresee rapid climate change. Porterbrook is currently reviewing rolling stock standards to identify aspects that need to take account of the changing climate.
One consequence of this is that trains do not always keep passengers comfortable. For example, due to higher temperatures the specification of heating, ventilation, and air conditioning (HVAC) systems require them to operate almost continuously which makes them more prone to failure. As a result, Porterbrook is trialling variable HVAC temperature set points to maintain the coach air temperature relative to that of the outside air temperature, rather than at an absolute value. Research indicates that, on hot days, passengers want a coach that is noticeably cooler than the outside air rather than an absolute temperature setting.
Another Porterbrook trial is the application of thermal window film which has been shown to offer a slight reduction to coach temperature. Colin advised that the preliminary design for the LNER tri-mode units that have recently been ordered from CAF incorporates solar reflective windows and HVAC systems with variable temperature set points.
Smoothing power demand
With parts of the OLE feeder system already running at their full capacity during peak demand, managing traction power demand is becoming increasingly important.
Furthermore, the demand for electrical power will increase as more electric, battery, and bi-mode trains are introduced. Accurately predicting this demand in real time to make smarter use of the available traction power supply is the aim of RSSB research report T1270. The authors of this report, RSSB’s principal energy engineer, Chibuzor Edordu and Navitas Engineering’s principal design engineer, David Allchin explained the findings of this research.
This work showed that assessing the power system capacity was not straightforward as it is subject to various constraints which include voltage harmonic and unbalance limits, grid transformer thermal limit and system and pantograph voltage limits with the key constraint being conductor, and cable currents adjusted for ambient temperature.
The T1270 report considered how the power demand from existing and proposed services could be predicted and regulated either by taking operational decisions to limit demand or by real-time controls. Such controls include connected driver advisory systems, direct control of the train traction control management system, and the use of intelligent substation electronic controls as specified in the international standard IEC 61850.
This presentation showed how the T1270 research project work can usefully support the management of OLE feeder systems that are running at capacity. However, it was not clear how it could support long term strategic planning, given the uncertainty of future rolling stock procurement and lead time to upgrade power supplies. What is evident is that if trains are no longer to be powered by diesel, an equivalent amount of additional electrical traction power is required.
The use of high-speed flywheels to recover energy and support rapid traction battery charging was described by Professor Keith Pullen, Levistor’s chief technology officer. Whilst Keith accepted that flywheels are more expensive than batteries, they offer various advantages which include lower embodied carbon, a +20 year lifetime and their power absorption matches that of train braking and acceleration. He considered that flywheels were more cost-effective for applications with a high number of daily charge/discharge cycles due to the cost of cell replacement and need to oversize batteries for peak demand.
The cost of fitting flywheels is also justified by potential fuel savings. An RSSB project simulating flywheel fitment on two-car Class 156 operating between Norwich and Sheringham concluded that they offered 43% fuel savings. Keith also explained the failsafe modular design of the Levistor flywheel which only requires light containment. This is because the flywheel is laminated and should a single laminate fail, the resultant unbalance will stop the flywheel.
Andrew Barr, Hitachi’s president for Europe, Middle East and Africa, gave an informative presentation on the need for holistic battery management. With alternatives to fossil fuels needed to meet carbon reduction commitments and around 40% European rail lines not electrified, he saw a significant requirement for battery powered trains which could be either new or retrofitted trains.
As an example of a new train, Andrew mentioned the Trenitalia Blue train which is an example of Hitachi’s Masaccio platform. This is Europe’s first tri-mode train powered by battery, diesel, or electric traction with the battery recharged enroute. This offers a 50% carbon emission compared with diesel trains.
Retrofitting the world’s largest rail vehicle battery to Transpennine Class 802/2 units is an example of what can be done with existing rolling stock. This retrofitting involved the removal of the motor car’s generator unit, fuel tank, and exhaust and the addition of a box for a 700kWh battery, roof mounted cooling system, and battery protection. This battery vehicle is now under trial to inform the business case for a 100%-battery-electric intercity train that can run up to 100km in battery mode. Potentially 1,000 generator sets on Class 8xx units could be replaced by this battery which has been developed using automotive battery technology.
Andy advised that the expected life of rail and road vehicle batteries is eight to 10 years, after which they can be re-purosed, recycled, or scrapped. He advised that a huge wave of end-of-life batteries is expected after 2030 for which it is critical to have the right facilities, markets, and regulations. He considered that there was a significant demand for second life batteries, for example data centre backups and static battery energy storage systems for back-up power and peak shaving.
To discourage scrap and landfill, he considered that it was important to have battery passports to manage the cradle to grave lifecycle which would, for example, promote innovative recycling to increase raw material recovery. Andrew also felt that there is a need for alternative models of battery ownership, incentivising good battery management through residual values. He noted that First Group has formed a joint venture with Hitachi to purchase up to 1,000 electric bus batteries to make best use of their second life.
Andrew concluded his presentation by emphasising that although batteries are now a credible rail traction option, they need to be supported by innovative commercial solutions.
Wide-ranging sustainability
The many topics addressed by the presentations at this IMechE seminar demonstrated that sustainability has many aspects. In essence, these covered the need to adapt to extreme weather and rail decarbonisation. Yet, as the industry’s Sustainable Rail Blueprint shows, there are even more aspects to sustainability which is a big topic.
The issues addressed by this event showed that much useful work has already been done to enable rail to continue to both operate a safe, reliable, and comfortable service in extreme weather and eliminate diesel passenger traction. However, much more remains to be done. Much of this is for the industry to action, though rail decarbonisation requires Government to commit to a strategic whole-system plan. Yet this requires the Treasury to be convinced that the rail industry can deliver much-needed electrification and power supply upgrades in a financially sustainable manner.
By running this seminar, the IMechE’s Railway Division has performed a valuable service by showing what needs to be done.
Image credit: iStockphoto.com
