The Railway Division of the Institution of Mechanical Engineers ran its 13th Railway Challenge over the weekend of 28-29 June. Though this a well-established event, there is always something new. This year this was a turntable, ride-on locomotives, and the event’s greatest and furthest international participation.
Regular readers may be familiar with this event on which Rail Engineer has reported since the first event in 2012. For those that aren’t here’s a brief description.
Rules and specification
A steering group directs the production of the competition’s rules and technical specification. The rules specify a maximum team size of 15 who must be either a student, graduate of no more than two years, or an apprentice over the age of 18.
The rules also specify maximum scores for six track challenges:
- Autostop (300)
- Ride Comfort (150)
- Energy Storage (300)
- Traction (150)
- Reliability (200)
- Maintainability (150)
In addition, there are four presentation challenges: Design (150); Business Case (150); Technical Poster (150); and Innovation (150).
Finally, there are optional challenges: Autocoupler; Aerodynamic drag; Ride-on locomotive; Location announcement; and Remote Data Recording and Monitoring.
The technical specification requires teams to produce a locomotive weighing no more than 2,000kg with an axle load not exceeding 500kg within the Stapleford railway’s loading gauge. The locomotive must have a maximum speed of 15km/hr and be able to operate for three hours without refuelling at a continuous 5km/hr up a 2% gradient, with a 400kg trailing load.
The rules allow for entry level teams who compete in the four presentation challenges plus an additional computer aided design (CAD) challenge that requires a report analysing their design by CAD software. The intention is that entry level teams will use their entry as the basis for a locomotive to be entered the following year.
Prior to the event, the teams must submit their design report, innovation paper, method statements, video of their locomotive testing, and an A0 poster summarising the locomotive technical specification. The teams must also deliver a virtual business case presentation to ‘sell’ their locomotives.
During the challenge weekend, the first task is scrutineering, which requires locomotives to satisfy a 33-point check list to confirm they are safe to run and are built to the specification.
To avoid the teams submitting the same locomotive each year, some challenges are varied each year as new requirements are introduced, and some are withdrawn. For example, new this year was an optional ride-on locomotive challenge. In 2018, the requirement to produce a technical poster was introduced. This encouraged teams to show their locomotives’ advantages and gave spectators, including your writer, a good understanding of the technologies used by each team as described below.
FH Aachen
FH Aachen University of Applied Sciences in Germany first entered the competition in 2017, making this their eighth appearance. They won it in 2019 and 2022. The 15 members of their interdisciplinary team included mechanics, mechatronics engineers, and business students who were accompanied by four supporters. Two weeks beforehand, the team entered and came second in the European Railway Challenge which took place in Bad Schussenried.
Their locomotive, named Carla, was the team’s third. It was built to carry a driver and had a new control system arrangement in which, rather than using a PLC, multiple microcontrollers were used to independently activate and test smaller subsystems. An interface on the driver control board enables microcontrollers to communicate with each other. This system reduces complexity and wiring as well as making it more manageable.
Carla was powered by LTO batteries connected to the motor controller via a CANbus. Its bogies had dampers and ‘pneumatic muscles’ for radial steering. Normal braking was by an electrodynamic service brake controlled by the motor controller. There was also an emergency braking system which comprised a compressor, accumulator, valves, and spring-loaded brake callipers.
Alstom and University of Derby
A mix of 15 graduates and students from academia and industry formed the combined Alstom and University of Derby team. Such teams first entered the competition in 2016, making this their ninth appearance. Although they have not yet won the event, the Alstom/Derby team came second in 2023 and 2024.
Their locomotive was powered by four lead-acid batteries and two capacitor banks of 185F which enabled rapid recovery of kinetic energy from during regenerative braking. On each bogie there was a DC electric motor bogie driving both axles through a chain drive. The bogies had electromagnetically operated friction brakes, and a rubber primary and pneumatic bellows secondary suspension.
The control system used Raspberry Pi computers to transform driver inputs into signals that operate the locomotive systems and feed information from them back to the driver. Arduinos and motor controllers read the signals produced by the Raspberry Pis and controlled the electrical and electro-mechanical systems.
The locomotive’s body was constructed from an aluminium frame with steel flooring and aluminium / acrylic panels. It had a bi-directional seat that could accommodate a seated driver designed for a ninetieth percentile male.
Network Rail and Colas
The combined Network Rail (NR) and Colas team comprises 15 graduate engineers with representatives from each of NR’s five regions who come together at the Colas Rail Depot in Rugby to assemble and test their locomotive whilst design work is performed remotely. A Network Rail team first entered the competition in 2019 making this their sixth appearance. The team first partnered with Colas in 2022.
Their locomotive was constructed from aluminium extrusions to resemble Network Rail’s New Measurement Train Power Car. As it did not carry a driver, it was remotely controlled from a trailing coach. It was powered by three 12V 75Ah lead acid batteries and a 166F supercapacitor for energy recovery and regenerative braking.
Its autocoupler had guiding rams for alignment and coupling hooks that lock with compression springs with an actuator that retracts the assembly for uncoupling. The coupled status was monitored and displayed on the handset.
This year the bogies were redesigned to enhance maintainability with integrated secondary jacking, provide a primary and secondary suspension that filters out 1Hz and 3Hz vibrations, and had electromagnetic service brakes with an auto engage failsafe.
Newcastle University
Seven mechanical engineering students made up the team from Newcastle University which first entered the competition in 2023, making this their third attempt.
Their locomotive built on the work of previous Newcastle teams. Unlike other entries, it did not have bogies. Instead, its two wheelsets had primary suspension springs and were connected to the body by anti-vibration mounts.
It was a dual gauge locomotive as it was first tested on a nearby 9 ½ inch railway after which axle spacers and friction locks enabled it to be converted to the 10 ¼ inch Stapleford gauge in a few hours.
It was powered by two 24v 100Ah LiFePO4 lithium batteries driving a brushless three-phase permanent magnet synchronous motor on each wheelset through belt drives.
The two motor controllers, Onboard Control Unit (OCU), and the handheld controller form a CANbus. The OCU handles onboard sensor data, lighting control, and location announcements. A new handheld controller was wired to the locomotive for use from its trailing car. The locomotive was not built to carry a driver.
Nuremburg
The team from Nuremberg Institute of Technology comprised nine students of various backgrounds including computer science, mechanical engineering, process engineering, and electrical engineering. Although this was the first time that Nuremburg had competed in the challenge, they had entered and won the European Railway Challenge two weeks beforehand.
Their locomotive did not accommodate a driver and had an unusual Bo-A wheel arrangement with one bogie and one wheelset. All three ‘wheelsets’ had stub axles with each driven by a 1kW motor. These six motors were powered by a 48V lithium iron phosphate battery. The power management system was designed for nominal 130A and high discharge 300A currents with individual 100A motor fuses.
Service braking was by electrodynamic braking with integrated holding brakes. The emergency braking system was spring loaded and released by a valve admitting CO2 from compact cylinders.
The location announcement system used components mounted on a self-designed, 3D printed frame to detect trackside RFID tags. This made a voice announcement which then showed the location on a self-built LED display.
Poznan
Team PUTrain was 15 Polish students from the Poznan University of Technology accompanied by eight supporters. Poznan first entered a team in 2019, this being their sixth appearance. They won the Railway Challenge in 2023. Like the two German teams, they took part in this year’s European Railway Challenge where they won the Technical Poster challenge.
Their locomotive was the third they have built from scratch. It could accommodate a driver sitting inside the vehicle which was 3.2 metres long and weighed 850 kg. The driver’s control panel had two displays, one for driving parameters and another showing the live feed from four on-board cameras. The driver’s joystick directly controlled the locomotive’s speed and had a vigilance button which, if not kept pressed whilst driving, activated the emergency brake. The locomotive had a fail-safe pneumatic braking system as well as electrodynamic braking with a system to measure the amount of braking energy recovered into the batteries.
It was powered by four lithium-ion batteries with a nominal total voltage of 72V and capacity of 72 kWh. Through a PLC controller, these batteries powered two 3kW AC permanent magnet synchronous motors. Each one was mounted on the bogie frame to drive the wheelsets by a planetary gearbox and belt drives.
The bogie’s primary suspension used horizontally positioned rubber springs to control the travel of the swing arms that house the axle bearings. The secondary suspension was an air bag between the bogie and locomotive body.
University of Sheffield
The Railway Challenge at Sheffield (RCAS) is a student-led club with about 30 undergraduate students from all years across multiple engineering disciplines. Thus, its final-year students have significant experience of the challenge. RCAS fielded a team of 14 at this year’s challenge which it had entered every year since 2015, making this its tenth challenge. RCAS won last year’s event.
Their new locomotive was built to accommodate the driver. Its bodywork was designed to reduce drag for which wind tunnel testing showed the drag coefficient to be 0.55. Primary suspension consisted of eight coil springs per bogie with secondary suspension using air bellows. This had been tested and tuned in laboratory and track settings to deliver a smooth ride.
It was powered by four LiFEPO4 12V batteries with a capacity of 180Ah with a 48V 166F supercapacitor operating in parallel across a DC-DC converter. These drove two 5kW brushless DC motors through a 12:1 reduction ration gear-train drive. A maintainability cuff enabled the quick removal of a driven wheelset.
The auto-stop system used a dual beacon infrared triggered technology.
Transport for London
The TfL team consisted of 15 first- and second-year graduates and apprentices, who were accompanied by ten supporters. TfL has entered the challenge on ten occasions and, of the team’s present, were the first to enter it, having done so in 2014 when they won the challenge. They also won the competition in 2015 and have come second on three occasions.
The driver sat in a car behind the locomotive using a control panel which has a touchscreen control. This was wired to the locomotive and has a CANbus communication protocol to minimise cable connections.
The locomotive was powered by four 24V / 100Ah LiFePO4 batteries and a 16V 500F supercapacitor providing secondary energy storage. A Sigmadrive PMY445M motor controller controls the power to brushless DC motors on each bogie. These drove the wheelsets by a chain and sprocket system with a 1:3.53 gear ratio that has sprung arm idler sprockets to tension the chain in both directions.
To reduce vibrations, the bogie had resilient wheels. Primary suspension was a set of helical springs and secondary suspension used air bellows inflated by an air compressor.
Its autostop detection system has a laser, reflector, and sensor which generated a signal to control the brakes to bring the train to a controlled stop at 25 metres.
Entry level competitors
This year there were four teams competing at entry level. These were:
- Anglia Ruskin University’s Team Heron, who are part of the University’s STEM Society. The team comprised of 15 mechanical engineering, electrical engineering, computer and business students.
- The Cambridge University Locomotive Engineering Society (CLUES) team with 12 engineering and natural sciences tripos students
- Team GWRC (Guided Ways Railway Challenge) made up of 15 students from ESTACA (École supérieure de technique aéronautique et de construction automobile), an engineering school in Paris that trains automotive, aeronautical, railway, shipping, and aerospace engineers.
- Monash Railway Express (MREx) were seven students from Monash University, Australia
These teams had to give presentations on the design and CAD analysis of their locomotives, the business case for the locomotive, and its innovative features. In addition, they had to produce a technical poster of the locomotive that they expect to enter in the following year’s Railway Challenge.
Notable locomotive features were shown on these posters. Team Heron proposed flywheel energy recovery; CLUES offered generator, hydrogen fuel cell or battery propulsion; and GWRC offered a brake particle recovery system and MREx offered dynamic real-time suspension control.
The railway
The Stapleford Miniature Railway is a10 ¼ inch gauge, 1/5th scale railway which is 3km long with a balloon loop and a station with sidings. As operators of the railway, the FSMR is crucial to the success of the challenge. They control all train movements, provide a rescue locomotive, and a guard on each train. An important principle is that the FSMR controller controls all train movements and only accepts requests for movements from the Railway Challenge’s operational controller, Bridget Eickhoff.
New this year was a turntable with spurs having hard standing for 19 locomotives. Bridget explained that, as well as providing this additional hard standing, the turntable makes it much easier to change the operational plan if a locomotive is not ready in time.
During the Railway Challenge, the turntable was ceremonially opened by the IMechE’s CEO, Alice Bunn; Organising Committee Chair Professor Simon Iwnicki; and Lord Gretton, whose family established the railway on the Gretton estate in 1958.
The FSMR’s Richard Coleby, explained that the turntable had been designed by FSMR three years ago and had been two years under construction. The FSMR has also actively supported by organising various volunteer weekends of which there had been three this year. These included Railway Challenge teams and IMechE Railway Division young members.
This project was also supported by Lord Gretton, AtkinsRéalis, Alstom, HS2, the Universities of Huddersfield and Sheffield, and Network Rail who surveyed the site and donated ballast. The turntable’s beams were crane support beams from a closed iron foundry, and its main bearing is from a truck axle.
The Railway Challenge takes place over three days. During the Friday and Saturday there was static and dynamic scrutineering as well as maintainability and autocoupler challenges. In addition, teams had the opportunity to do practice runs on the railway. The track-based challenges were undertaken on the Sunday during which a spectator train operated was hauled by a FSMR steam locomotive.
Currently, the railway can accommodate two locomotives an hour undertaking track challenges which limits the number of locomotives that can be tested during the day to 12. To increase the railway’s capacity and flexibility, there is a proposal for a holding loop close to the balloon loop, together with a chord to enable the balloon loop to provide a continuous circuit.
The results
The marquee erected for the challenge was packed with almost 180 competitors, many spectators, 19 volunteers from the IMechE Railway Division, and others for the prize giving hosted by Chief Judge Bill Reeve. Bill stated that it had been another absolutely fabulous year. He mentioned that he and his fellow judges were inspired by the competitors’ enthusiasm and commitment, which makes their job such a pleasure. He noted that each year the judges always learn from the competitors.
He then proceeded to invite individuals involved with the competition to present its 18 prizes. Whilst doing so he mentioned some quite impressive achievements. Nuremburg had won the autostop challenge with an astonishingly accurate 11 centimetres difference from the target stop point. Network Rail won both the optional autocoupler challenge and the energy storage challenge with a seriously impressive distance travelled from recovered energy alone of more than 45 metres, the second-best result in the entirety of the challenge. Aachen had won the maintenance challenge with a time of only 72 seconds to lift the loco, take the wheel out, put it back, lower the loco, and have it ready to run again. Poznan won the optional ride-on and aerodynamic challenges.
He advised that the result of the business case challenge was incredibly close with Network Rail winning by only one point. After announcing that the entry level prize had been won by our friends from la belle France ESTACA, the overall prizes were announced. Third was Aachen with 1,498 points and second was Nuremburg with 1,545 points. With 1,603 points the overall winner was Network Rail and Colas.
The full list of prizes and rankings are shown in the table, but for all competitors the real prize was the experience of delivering a railway engineering project to a strict deadline without risk to their reputation. Previous competitors, some now in quite senior roles, advised that they found the Railway Challenge to be a valuable learning experience.
On a personal note, when reporting on the Railway Challenge it is always a pleasure to experience the buzz at Stapleford and see the effort and enthusiasm displayed by the teams. The work done by a large number of Railway Division volunteers both at the challenge and beforehand is impressive. The challenge also depends on FSMR members and IMechE staff to ensure its success.
The financial contribution of sponsors AtkinsRéalis, Angel Trains, and Network Rail must also be acknowledged.
Image credit: David Shirres