Railway Challenge


Railway Challenge - Your questions answered

Please note that the FAQs are subject to the rules and technical specification of their respective year as some FAQs are outdated or are no longer relevant due to the rules changes that occur each year. Please enquire to double check at railwaychallenge@imeche.org.

FAQs 2024

How heavy are the load vehicles during the event?


Each load vehicle has a nominal mass of 200kg. For 2024, two load vehicles will be used. The mass excludes persons onboard. For the challenge runs, there will be a minimum of a driver (either on the load vehicle or from 2024 potentially in the locomotive), a judge and a guard onboard. Teams may opt to have additional members onboard if they choose.

How soon after the submission of the optional challenge preference order will the teams know if there preference has been chosen?


We will advise as soon as we can. Entry closes 20th November and teams must notify us of their optional challenge preferences within one month of entering. We will therefore hope to advise of teams’ optional challenges by Christmas at the latest. However, in line with Rule B2.2, as soon as two or more teams have a preferred option confirmed, we will be able to notify those teams.

For the new location announcement challenge, are teams allowed to place physical markers beside the track to be detected by the locomotive and initiate an announcement?


There is nothing in the Rules or Technical Specification prohibiting the use of lineside markers for this challenge. However, teams should note that announcements when coming to a stand will not necessarily coincide with any specific position.

Due to the removal of refuelling challenge, are teams still restricted to a maximum of 25 kg for the energy storage asset?


The refuelling challenge has been removed, but all requirements relating to refuelling remain in the Technical Specification.

Notification of the optional challenges


Concerning notification of the optional challenges, teams were required to register by 20th November. As per Rule A21, teams are required to submit their optional challenge preference order within one month of entry being confirmed. As per Rule B2.2, the organisers will confirm the teams highest preference with at least one other team competing. We will seek to notify teams of this at the earliest opportunity, prospectively by early December and hopefully before Christmas at the latest. Teams will be required to compete in their preferred challenge as notified. Once all teams’ options are confirmed, we will then publish these – this will indicate which of the optional challenges are available for competition in 2024. As also per Rule B2.2, teams may then also compete in the other optional challenges where other teams are also confirmed as competing (as the organisers publish). Due to the scoring of these optional challenges, it will be in the interests of each team to compete to the best of their ability in each optional challenge they compete in, in order to maximise their score relative to that of their fellow teams. For any optional challenge which no other team selects, it will be possible to compete in these also, but no score will be recorded.

Ride comfort challenge - Is there a penalty for taking longer than the allotted 6 minutes to complete the challenge? If so, how is this factored in to the score? Could you post the times it took the teams to go around the course?


Regarding the ride comfort time, if the team takes longer than 6 minutes to complete the run then the attempt is invalid. In such instances, if it was possible to acceptably fit the accelerometer, the team will only get the 1/3 of the marks allocated for attempting the challenge. As Rule C2.6 states, this is achievable with an average speed of 10 km/h but teams are advised to validate this in their test runs and not to rely solely on this as a means to ensuring they are within the permitted 6 minutes. In 2023, teams took between 5m06s and 6m00s for compliant teams. Note, however, that this is times from the meter which are likely to be a few seconds longer than the actual run. The riding judge will use a stopwatch to determine the run is within 6 minutes but we do not have a record of these times.

Ride comfort challenge - What make and model of accelerometer and data logger is used during the competition?


For the Ride Comfort Challenge, the Railway Challenge has until now used a Larsson Davis HVM100 vibration meter together with a Larsson Davis SEN027 triaxial accelerometer (removed from the seatpad it is supplied with). However, the organisers reserve the right to use alternative equipment for future events. All meter and accelerometer setups capable of measurements using the MCSM method in accordance with EN 12299:2009, as defined in rule C2.8 will be acceptable.

"The option for teams to compete with ride-on locomotives for the driver, provided they complete an acceptable hazard analysis"

As this is to become mandatory for the 2025 competition and we are competing in the design competition, we are obviously hoping to design for the 2025 competition as far as possible so this would be a key design consideration. However, I can’t find any references to this in the technical specifications or rules so was wondering if there are any specific requirements regarding this or whether it is just a case, like with other challenges and parts of the competition (e.g., unloading the locomotive), of ensuring appropriate risk analysis and mitigation are in place? 

If the locomotive can be ride-on, can it also be controlled with an integrated control panel as opposed to a remote.


It is correct that there are no further details of the ride-on driver requirements in the Technical Specification for 2024. The organisers will include some such requirements in due course, either in the Technical Specification or in a supplementary document given the ability for the driver to be onboard the locomotive is optional for the 2024 competition. Such requirements will be as follows, which are provided in response to this query but will take a similar form in the Technical Specification or in a supplementary document:
Operation of the locomotive may alternatively be by a driver onboard the locomotive for the 2024 competition (noting that it is proposed to become a mandatory requirement for the 2025 competition). For a driver onboard, teams are required to:
• Complete a risk assessment for the provision of a locomotive design for an onboard driver considering the additional risks to the driver and/or locomotive operation that this introduces. The following risks, as a minimum should be considered, with the design demonstrating that identified risks are reduced to an acceptable level:
• Ride and risk of derailment with a driver onboard the locomotive (thereby affecting the wheel loading)
• Risks of injury to the driver including heat, electric shock, moving parts, and the potential for fire/explosion
• Ensuring suitable containment for the driver, but also providing a means for rapid evacuation as required.
• Onboard driver provision shall be for 5th percentile female to 95th percentile male. With reference to Technical Specification 4.3, it is not required for onboard drivers to be within the dynamic loading gauge. However, it should be demonstrated that a 95th percentile male can comfortably position themselves, whilst sat in the locomotive, such that the top of their head is below 1500mm above rail level.
• To enable bi-directional operation of the locomotive with an onboard driver, consideration should be given to the ability for the driver to control and operate the locomotive in both directions, including enabling them to have visibility in both directions. Note it is not specifically required for the driver to be able to be seated facing directly in both directions, provided the aforementioned is considered.
• With reference to Technical Specification clause 2.2, the requirement for remote operation as per this clause will remain, permitting the locomotive to be operated also either from the trailing load or, for slow speed movements, with the driver waling alongside the locomotive with the controls handheld. Rather than duplicating controls integrated into the locomotive, it is recommended that teams instead provide for the remote control device(s) to be mounted in the locomotive to provide for onboard operation.
• With reference to Technical Specification clause 4.4, the total mass stated is for the locomotive excluding the mass of the onboard driver.
• With reference to Technical Specification clause 4.9, for teams selecting the Aerodynamic option, air resistance shall be determined with no onboard driver.
• With reference to Technical Specification clause 5.4 6th bullet, provision of a second emergency stop on a flying lead accessible to the riding judge situated in the load vehicle coupled to the locomotive is also required.
• With reference to Technical Specification clause 5.7.1, indications should be visible to both the onboard driver and the riding judge situated in the load vehicle coupled to the locomotive.
For teams providing a design with provision for an onboard driver in 2024, if accepted in line with the above requirements, and accompanied by a suitable and sufficient risk assessment demonstrating to the satisfaction of the judges that risks for onboard drivers are acceptably mitigated the locomotive design will also be provisionally accepted in 2025, contingent on successful operation of such locomotives in 2024. The organisers reserve the right to amend or add to the requirements in the event that this is deemed necessary for a safe and fair competition. For entry level teams in 2024, similar will apply if they propose a design for an onboard driver in 2024 compliant with the above along with an acceptable risk assessment.

Auto-stop - In clause 5.5 of the tech spec it states no tractive effort will be applied in this mode

Does this mean that the loco should effectively coast upon passing the marker with no power whatsoever applied to the traction motors or can the loco maintain a speed (not accelerating)?


Regarding the Auto-Stop Challenge, ‘no tractive effort’ as referred to in Technical Specification clause 5.5 means that no positive tractive effort may be applied. Therefore, the locomotive must only coast or be retarded by the brakes: it cannot be driven forward (even at a constant speed) but must be controlled only through braking. Teams are expected to acceptably demonstrate this through their design report and, as required, in scrutineering also.

Specification 5.9 states that announcements are for “all occupants of trailing vehicles”.

Does this mean that announcements need to be heard/seen in the very rear carriage (where the guard is seated)? If this is the case, are we permitted to supply and use additional remote hardware which is not physically attached to the locomotive?


The Technical Specification, by design, does not rule out the use of additional hardware. As a minimum, the announcements should be capable of being heard/seen by the first two occupants seated in the trailing vehicle which will include the riding judge.

In Specification 5.10 (Remote Data Recording challenge), one of the requested data points is location.

Is there a required level of precision for this data? i.e. does ‘train has passed point X’ satisfy this requirement, or does the challenge require a pinpoint on a map?


The Technical Specification, by design, does not specify accuracy. It can be assumed that better accuracy will be viewed favourably by the judges. Teams should therefore consider the ease of immediate interpretation of the locomotive location accuracy relative to the track infrastructure by the judges in their presentation of location information.

Specification 6.2.2 states "The design of the auto-coupler will tolerate a height above rail head of the connecting vehicle’s coupler from the specified height

(Clause 6.2.1 refers), -2” / +3”. Height adjustment may be via any means other than manual handling of the coupler itself".

The team would like to seek confirmation that the amount of required adjustment is 5 inches (rather than 5 cm), as this will be a large variability for our small locomotive and coupler system.


The committee is planning to measure the height of a coupler with increased accuracy (smaller tolerance range) at the site visit on 7th February. If successful we will provide these details to teams and upload to the Challenge website.

Is it possible for a more specific height coupling bracket on the trailing vehicle above the track level, it is currently a 50% tolerance on the 10" height above the railhead?

  • Is the possible height continuously variable or is it set based on the trailing vehicle type used, in which case is it possible to be given these heights?
  • What is the interface between our Auto-Coupler apparatus and the trailing vehicle?
  • Are there technical drawings of the U- / Box- coupling bracket fitted to the trailing vehicles?

Can we be provided with technical drawings / engineering diagrams for the above queries?

We also have a query regarding the location announcement challenge. Is it possible to be provided with the GPS coordinates of the location announcement positions?


  • As per Technical Specification clause 6.2.2, teams are required to autocouple to the vehicle by a means provided by the team, and this may include items fitted to the vehicle being coupled to.
  • Also as per Technical Specification clause 6.2.2, the interface on the vehicle to be coupled to will be the same as for a standard drawbar. This comprises a ‘U’ bracket mounted on the end of the vehicle through which a pin is inserted with the drawbar through the middle. Photo below.
  • The draw and buffing loads of the coupling interface should principally take by the pin through the ‘U’ bracket, but the ‘U’ bracket and vehicle end panel on which this is mounted may also be used for maintaining the position of any device fitted to the vehicle end for the purposes of autocoupling.
  • The organisers will provide further details and dimensions of the ‘U’ bracket arrangement on the vehicle to be used in the autocoupler challenge following the site visit in February. Teams attending this site visit may also make their own measurements and/or record other relevant details or take photos.
  • The organisers cannot provide GPS coordinates for the location announcement positions. Teams are required to establish these and may do so remotely with reference to the 2024 point positions map attached. The organisers reserve the right to make minor amendments to the respective points in setting these during the challenge weekend. As such teams’ solutions to deliver against the requirements for this challenge should take account of the potential need to make amendments to the position coordinates during the challenge weekend, or develop a solution that otherwise delivers automatic location announcements at the correct locations.

What are the 10 points of data for the Remote Monitoring challenge? I can see a list in the Tech Spec, but when I count them, I can’t get exactly 10, normally a few more/less depending on the way I count them.


As per rule B2.3, there are 10 data signals to be monitored and recorded with 10 points awarded for successful delivery of each (five points for monitoring and five for recording). As per Technical Specification clause 5.10, the 10 data signals also include those mandatory indications under clause 5.7.1. For the avoidance of doubt, the 10 data signals are:

1.       the location of the locomotive

2.       traction/brake demand from the driver

3.       brake system fault

4.       traction application by the locomotive

5.       brake application by the locomotive

6.       fuel or charge level

7.       status of recovered energy system

8.       locomotive speed

9.       automatic braking mode selected (active)

10.     autocoupler status (coupled/uncoupled)

For recording of these data signals, a timestamp is also required.

In Clause 5.4, a new requirement has been added in that “The remote control unit shall include a second emergency stop button on a flying lead accessible to the riding judge”.

Our system uses an off the shelf wireless controller, as such, Would it be acceptable for the E-Stop button to be connected to the rear of the locomotive, rather than the controller?


As per Technical Specification clause 5.4 item 6, an emergency stop button on a flying lead accessible to the riding judge is required. The organisers confirm that it is not essential for the flying lead to be from the remote control unit, it can instead be direct from the locomotive provided it delivers the required functionality.

Regarding the specifications for 6.3.2 "Jacking or lifting for maintenance" in this year's Technical Specification:

Is it necessary to replace the power wheelset with a new one or do we just have to dismantel the wheelset bevor putting it back on? And if so, how far do we have to remove it from the locomotive before putting it back on?


Teams can put back the wheelset they remove. Removal has to be to a place completely away from the locomotive – reflecting the scenario where it is taken away for maintenance or repair.

Please provide details of the coupling bracket to be used for the autocoupler challenge


Concerning the autocoupler challenge, the vehicle provided to couple to will have a coupler bracket as per drawing IMECH-MISC-001-B which has been provided in the document library. This provides dimensions for the coupler box and its height above rail level. As per a FAQ already responded to, the principal load should be primarily taken on a couple pin passing through the 20mm diameter holes. As per Technical Specification clause 6.2.1, the coupler pin shall be of diameter 3/4" (slightly smaller than 20mm so as to provide clearance). The coupler pin may be as supplied with the vehicle or of the team's provision.

In developing their autocoupler solution, teams are also advised to ensure that, when coupled, it is able to negotiate the track features of the railway and also accommodate dynamic movements of the locomotive and coupled vehicle.

I'm developing a new method of detecting lineside markers for the Newcastle Locomotive team and was hoping to get an 'okay' on the marker. Please could this email be forwarded to an appropriate member of the Railway Challenge organisation team.

The plan would be to have a series of infrared beacons positioned between the two rails. These would be contained in watertight plastic boxes. The rough dimensions I am looking at are L10  B5  H5cm to be positioned on the ground between the rails. This small size was decided to ensure the boxes are safely clear of any overcoming trains.

On the train there will be an IR detector to detect when we pass over one of the beacons.

Could you please confirm for me whether the proposed design would be suitable, and if I would have to place and remove the boxes before and after each of our runs on the track.


In answer to your query below, teams are free to design any lineside equipment in any way they wish and this may be placed between the rails if preferred but teams must be able to demonstrate that any such equipment is outside the loading gauge. Teams should note that the space between the rails is not consistent. In particular, the location of points, crossings and concrete slab areas needs to be understood.

Teams should be able to install / remove any lineside equipment when requested and this should take no more than 2 minutes.

For the Remote Data Recording Challenge, is the IMechE requesting that the system provides an option for the user to switch between graphical and tabular formats, of if the IMechE is asking that at least one of these formats is available?


Technical Specification clause 5.10 requires the data to be presented in tabular or graphical format. Teams should decide on how to present their data in conformance with this also considering the way the challenge will be assessed as per section C10 of the rules, also referring to the relevant part of clause B2.4. As per the latter, 25 points are available for the system design and this will consider the presentation of the data. Teams should consider how this can most effectively be presented, which may include the option of more than one format.

Also for the Remote Data Recording Challenge, does the 'graphical' format of data playback, refer to using charts/graph to display the data or non-text based formats in general?


Please refer to the response to the question above.

Spec 5.7.2 requires safety related lighting to deliver between 200 and 1000 lumens of output.

In the case of the direction lights, if there are 2 lights (left and right) on the front and back panels, does this requirement apply to the combined output of both lights on a panel, or to each individually?


The indicated brightness values are the total values for the lights in each direction.

For the auto coupler challenge, can teams use the coupling pin attached to the wagon, or are teams required to supply their own?


The vehicle provided for the autocoupler challenge will be provided with the coupling pins in the coupler box. Teams are at liberty to use this or an alternative arrangement as suits their design.

Could you please confirm whether the ‘U’ Bracket drawing (Drawing Number: IMECH-MISC-001-B) that was sent out is accurate and will be the one used on competition day?

Although it was mentioned on the 7th Feb that there might be three slightly different options, the drawing seems to indicate that it will be the one that is used.


It has been confirmed that vehicle 15BM will be used for the autocoupler challenge and drawing IMECH-MISC-001-B indicates the coupler boxes on that vehicle. Teams should note that dynamic tolerances should also be considered for the coupler box position as per this drawing relative to the team’s locomotive autocoupler interface.

We are writing to you regarding the Auto-Coupling-Challenge and the technical drawing provided of your coupling box labelled ‘Drawing IMECH-MISC-001-B Wagon Coupling Box’.

In this technical drawing, the height of the contact point of the coupling box is specified as 204mm to the rail head. In your technical specifications for the coupler (section 6.2.1) you request a U-bracket with a centre line of 10’’ (254 mm) above the rail head. Is it correct that we have to compensate for the height difference of 50 mm, or is it possible that this is a typing error in the technical drawing of the coupling box?



The organisers can confirm that there is no error in the coupler heights specified. The height for the centreline of the coupler U-bracket in the Technical Specification (10'' / 254 mm) relates to the fixed coupler for use with the coupler bar for use at all times during the competition weekend except for the Autocoupler challenge. This height is determined due to some variability in the height of couplers on other stock at Stapleford Miniature Railway. For the Autocoupler Challenge, drawing IMECH-MISC-001-B details the heigh of the coupler box on coach 15BM which is at a slightly lower height. Teams are required to provide an autocoupler interface with this coupler box specifically for this challenge, noting that dynamic tolerances should also be considered for the coupler box position relative to the team’s locomotive autocoupler interface.

In section 6.2.2 of the technical specification there is a provision for a tolerance on the height above the head of rail of the coupling vehicle.

The tolerance amplitude is close to 15 centimetres. In order to meet this condition, it is possible to change the coupling height manually or is it possible to change the coupling height manually or it is necessary to ensure this tolerance by the coupling design?


In relation to the autocoupler challenge, Technical Specification clause 6.2.2 provides details of the coupler height on the connecting vehicle. Whilst this is the required height range for the autocoupler solution to be compatible with, it has also been confirmed in drawing IMECH-MISC-001-B what the coupler height will be on the vehicle which will be used for this challenge. Teams are therefore advised to work to the coupler height indicated in drawing IMECH-MISC-001-B for the purposes of this challenge. However, should teams need to, the ability to adjust the height of their autocoupler solution may be provided also to meet the requirements of Technical Specification clause 6.2.2. Such adjustment, where required, may be made manually; however, as per the rules for the Autcoupler Challenge, no adjustment may be made during the challenge proceedings – adjustment may only be made prior to competing in this challenge.

FAQs 2023

Technical specifications/rules: maximum dimensions of the locomotive

Upon reviewing the rules and technical specification, I noticed that I cannot see any statements outlining the maximum dimensions of the locomotive. Would you please able to clarify the maximum width, height and length our locomotive is able to be built to?


The loading gauge defined in section 4.3 of the Technical Specification details the dimensional requirements to be complied with. This references drawing RC02 which is also available in the team resources on the website. However, there is no maximum length specifically required but this is likely to be limited based on compliance with other related requirements including those for mass and track compatibility (including running on curved track).

Technical specifications/rules: coupler bar design

For the coupler bar’s design, the specification suggests that we have a degree of flexibility in its dimensions, but I wanted to gauge what restrictions we need to work to so that we are still able to fit the carriages’ couplings and meet the specification’s requirements. Based on the ‘RC05 Drawbar’ drawing, given that only dimension noted as ‘obligatory’ is the 20mm diameter hole for the carriages, are we free to change more or less any of the other dimensions? For example, can we change things such as the coupler bar’s thickness and width?

I have noticed that, in various photos taken at previous challenges, many of the coupler bars are at an angle when they are hooked up to both loco and carriage. My questions are:

1. What is the nominal height of the SMR carriages when statically loaded? Or is there a range of height that the coupler bar can be at when attached to the carriages? If so, what is it?

2. Is there another reason as to why many of coupler bars end up being at an angle? Of course this changes how the coupler bar is loaded, so I need to ensure that it’s strong enough!


The drawing of the coupler bar provided is only an example and, as stated in the technical specification (section 6.2), “The coupler bar design (including length) shall be assessed against the track characteristics, haulage and braking loads as specified in this document, taking into due account the endthrow of the locomotive and all limits of dynamic displacement.” So to answer the first part of the question, teams are free to change the thickness and width of the coupler bar provided the above requirements are met.

Regarding the second part of the question: The Technical Specification states that the locomotive must include on each headstock “A ‘U’ bracket with centreline 10″ above rail head supporting a vertical shaft or pin of ¾″ diameter with suitable retention.” The 10” height is chosen to suit the most typical carriage used at Stapleford but there will be some variation and of course there will also be dynamic movement vertically and laterally between the loco and the carriage during operation. Teams should include allowance for the likely motion in their calculations.

Technical specifications/rules: section 5.3

In the technical specification, section 5.3, it is stated that the locomotive must incorporate two braking systems for both service and emergency braking, though these can use a common actuator. Our system incorporates a proportional solenoid valve to provide the brake actuators with air (the actuators themselves are spring applied, air release). If power is lost (for example by the emergency stop system being actuated), the solenoid valve is shut and the brakes lose air and spring on, hence we have an emergency brake *within* the service braking system rather than it being exclusive. Are we still compliant with the rules? I appreciate this is a complicated query and would be happy to talk through the diagram if necessary.


Yes, the braking arrangement described is a common design and, from the description provided, appears to comply with the technical specification. The scrutineers and judges will of course assess each locomotive at the Railway Challenge final against all the rules and technical specification based on the design report, the compliance matrix and the presented locomotive.

Technical specifications/rules: backstop to our auto-stop system and mechanically releasing air from the brakes

The second technical query is a bit more pie in the sky. We are thinking of how we might add a backstop to our auto-stop system, and the idea of using a system similar to London Underground's trip cocks  (i.e. mechanically releasing air from the brakes) was floated; would this be permitted?


Yes, a ‘backstop’ or secondary autostop system would be allowed but to be compliant with the rules for the autostop challenge it would have to be initiated automatically (ie without being manually triggered). The specific mechanism could involve the release of air if that is the preferred solution but any lineside device could only be sited at point A (refer to rule C1.10). No additional lineside device would be permitted after point A.

If the team are concerned that the locomotive is running away then they may manually activate the emergency brake which should function at any time. Manual activation of the emergency brake (or activation by a lineside device not at point A) would clearly indicate an abandonment of the autostop challenge attempt.

FAQs 2022

Technical specifications/rules: clause 4.1

Regarding clause 4.1 of the Railway Challenge 2022 Technical Specification, the clause states that the loco should be able to haul 1800kg up a 2% gradient. Should this be calculated for a worst-case condition utilising the coefficient of friction of 0.15 specified in section 7.1.1 of the 2022 technical specification? We were curious as this would imply a lower weight limit of approximately 750kg, however we have been told that there have been lighter locomotives than this in previous years.


The coefficient figures provided in Clause 7.1.1 are deliberately low / pessimistic as the safety related calculations they relate to need to be based on a worst feasible scenario. There is no implication that the figures provided have to be used for other purposes. Low coefficients for calculations relating to wheel flanges reflect the possibility of lubrication migration.

The Specification’s performance related clauses do not include a friction coefficient as we would expect teams to describe what figure they have assumed in the calculations that support performance compliance statements, to allow written submission judges to assess feasibility on a case by case basis, e.g. If wheel spin / slide systems were fitted, a lower figure might be accepted. I suspect they would be looking for between 0.17 and 0.21. As to what weight this implies; this depends on configuration – i.e. how many axles are driven and braked.

Another key factor with respect to compliance with Clause 4.1 is torque / tractive effort. Even with infinite adhesion, Clause 4.1 will not be met if this is inadequate, so this also needs to be demonstrated in the compliance submissions.

Maintainability Challenge: motor removal

In the maintainability challenge, is it acceptable to remove a motor that is integral to an axle-mounted gearbox on the wheelset we wish to remove?


Yes, this is acceptable.

Technical specifications/rules: ride comfort accelerometer

In conversation with one of the Judges at the Site Visit, we were advised that the ride comfort accelerometer could be mounted within the loco body, provided it is on a ferrous mount that is not dynamically isolated from the loco body structure, and that no part of the loco may be detached to install it. Is this correct/are there any additional conditions?


Clause 9.2.1 of the Technical Specification concerns the mounting of the accelerometer for the ride comfort challenge. Access to the mounting point is required to comply with this clause. For clarity, easily removed bodywork (not requiring any tool to remove) may be removed.

Technical specifications/rules: dynamic loading gauge

Our current loco design uses two steel rollers (one on each rail) connected to a motor (acting as a generator) to determine the speed of the loco. These two speed rollers fall outside the dynamic loading gauge, which appears to only permit wheels to contact the rail. Therefore my question is would these speed rollers be permitted as they fall foul of the dynamic loading gauge? (Drawings supplied)


The loading gauge is set at 10mm above the rail head height as there are some places where there is equipment between the rails which is slightly higher than the rail head or where the concrete surface between the rails may be slightly higher than the rail head height. We are prepared to allow a derogation to the 10mm height down to rail head level as long as this does not extend further than 8mm inwards from the inside face of the rail on either side. If the team apply this derogation they will have to complete an additional slow speed run over the potential problem areas to demonstrate that there is no interference with any lineside equipment / switches etc. If the rollers (or any other equipment likely to extend into this area) are not mounted close to the running wheels then the team will need to show calculations demonstrating that the throw on a curve will not move the equipment further than 8mm from the inside face of the rail. If the rollers are found to exceed this or have the potential to exceed it, then we may require them to be removed or lifted clear.

For this particular case the team will also need to consider the design of the mechanism holding the rollers including the rigidity of the arm the roller is mounted on and the strength of the spring. These should be sufficient to ensure that the roller does not deviate from its nominal position significantly with the movement (including vibration) of the locomotive.

FAQs 2021

Technical specifications/rules: regenerated energy

It has been brought to my attention that for the energy storage challenge last year, contrary to the technical specification, the regenerated energy could be directed back into the primary traction system, provided that it could be shown that the energy going in and out was the only energy used during the challenge. Is this still the case for this year's challenge?


We have updated the Technical Specification to allow regenerated energy to be directed back into the primary energy storage system provided that all other clauses in the rules and technical specification are met.

Technical specifications/rules: team members

Given the issues with COVID-19 and the nature of the competition from last year, where many teams did not build their locomotives is there potential for waiving the rule for 2021? 

No team may have more than 40% of its team members who have been members of a previous Railway Challenge team.


Due to the COVID-19 pandemic, this rule has been waived for the 2021 competition. The 2021 rules were updated on the website.

Technical specifications/rules: Drawings - loading gauge

Does this loading gauge drawing take into account the 20m minimum radius for the whole locomotive in terms of centre throw?


This is a kinematic envelope, the standard method of specifying loading gauge. It defines the dimensions of the railway, not a locomotive. To fit into the kinematic envelope, the design of a locomotive needs to factor in not only the maximum cross-section but its end-throw, centre-throw and movement (primarily re. suspension). The maximum locomotive cross-section will be notably smaller than the kinematic envelope. It will vary from vehicle to vehicle, depending on longitudinal dimensions (e.g. overhang, length between bogie centres etc.) and suspension characteristics.

Test track: the type of materials used for the sleepers, the depth of the ballast

We are planning to make a test track for our locomotive but for that we needed some information about the type of materials used for the sleepers, the depth of the ballast. We would be really grateful if we could find some information regarding this.


The railway track at Stapleford is constructed in different ways in different locations with varying rails and sleepers and fixings and welded tie bars so it is not possible to give a specification that would be representative of the whole route.

Several universities have constructed test tracks and we would be happy to put you in touch with these so that they can share details of their construction methods.

Traction Challenge: head of the rail width

How wide is the head of the rail at the location where the Traction Challenge takes place?


Traction Challenge: The rail used at that location is probably either S7 or 18lb/yd (which is slightly larger and heavier). A drawing of the S7 section is available here: http://www.miniaturerailwaysupply.com/rail/s7steelrail.htm

Although you should be aware that there may be some wear and the profile of the rails may vary slightly along the track. The width of the head of the rail is therefore around 25mm or possibly up to 30mm in places.

Why do I have to pay to formally register?

The team registration fees are used to help the Institution cover the running costs of the Railway Challenge. The student challenge portfolio is expected to break even and that is one of the reasons we engage industry partners who help us finance the competitions annually.

All participants are expected to pay the registration fees and many teams engage with local companies and have managed to secure sponsorship that helps them to cover the costs.

The IMechE helps provide funding via our grant schemes.

FAQs 2019

Auto-Stop Challenge: lineside markers

As part of the Auto-Stop Challenge where we have to place a lineside marker on point A and 25 m further bring the loco to a stop - are we allowed to place a sign on Point B (where the loco has to stop) too? Or is there at Point B no detectable marker provided/allowed? I couldn't find some information how Point B should be designed.


All lettered points according to the rules, including point B, will be indicated by the organisers using a board adjacent to the track. For the auto-stop challenge, teams are 
required to provide the marker to be detected by the locomotive at point A, which will also be indicated by the organisers using a board. The board at point B will only be for reference, and the locomotive’s braking system should be designed to enable it to 
automatically stop as close to this point as is possible without intervention from the
team in line with rule B6.5.

Auto-Stop Challenge: lineside markers positioning

For the Auto-Stop Challenge how will the lineside distance marker for each team be positioned?


Each team provides their own location marker device. A nominated team member (not one of those on board their train) will position this at Point A (as indicated by a lineside marker provided by the challenge management team) when instructed by the IMechE judge / marshal. Positioning of the device (and fastening if required) shall be completed within three minutes. Removal, after the train has passed, must be completed in no more than two minutes.

Locomotive design: final drive chain

Is it acceptable for the final drive chain to remain around the final drive sprocket, which is on the wheelset axle, when the wheelset is removed, provided that the chain is not too long?


Yes, there would be no objection to this as long as the chain does not in anyway cause a hazard.

Ride Comfort Challenge: ride comfort testing

For the Ride Comfort Challenge, what piece of equipment do you use to test the
ride comfort? I assume it is an accelerometer, but I was wondering which one
so that I could use the same for our testing?


The Ride Comfort Challenge will be run in accordance with the rules for that
Challenge. In theory at least, the result should not depend on the test measurement
equipment used if specified and configured according to those rules. Test results will
also be dependent on other factors, e.g. track characteristics) which may render results
from a team’s own testing different to those obtained at the competition. However, we
can confirm that a Larson Davis HVM100 meter is normally used for this Challenge in
conjunction with a Larson Davis SEN027 tri-axial accelerometer. However, the organisers cannot guarantee that this equipment will be used in 2019.

Technical specifications/rules: Changing wheelsets

In the Rules it says that we have to change a driven wheelset. Is it also allowed to change a driven wheelset as a complete unit with the motor together?


The powered wheelset must be completely removed from the locomotive. The wheelset when removed must consist only of the wheels and axle plus axle boxes, brake disks and the final part of the traction drive for example a gear/pulley or sprocket where attached to the wheelset. Other parts of the traction drive including the traction motor must be disconnected from the wheelset.

Technical specifications/rules: Lineside distance marker

Is it acceptable for the ‘lineside distance marker, provided by the team’ (Rules 2019, clause B6.2) to be positioned between the rails, provided it is outside ofthe gauge? The wording in B6.2 states that the marker ‘will be positioned adjacent to the track’, however we were told that placing it between the railswould be fine?


Yes, it is perfectly acceptable for the team’s distance marker to be positioned between the rails, provided it is outside the structure gauge. The lineside distance marker referred to in the Tech Spec is a location marker set up by the IMechE.

Tech Spec section 5.5 states: “Teams will be expected to provide and temporarily fix a detectable location device of their choice at the location of this marker. This device will be designed such that it is entirely outside the structure gauge limits (Drawing RC02 refers)”

Technical requirements/rules: recycling

“Clause 4.2.3 states that the team shall demonstrate 95% of components by mass can be disposed of in such a way that facilitates recycling” does this include reusability (reduce reuse recycle)? Our batteries powering our locomotive are borrowed from an electric train company, who we plan on giving them back to afterwards, they won’t be recycled.


All you have to do is show that they can be recycled, not will be. You need to research what happens to batteries of the type proposed when disposed of – land fill always (not ok) or potentially broken down and elements salvaged (ok).

Technical specifications/rules: tractive effort

Technical specification point 5.7 - A new requirement has been added stating: “Tractive effort applied”. Is this to be a continuous quantification of the amount of tractive effort applied similar to that of the energy storage indicator, or a binary indicator showing when traction is being applied regardless of the amount of tractive effort.


The tractive effort indicator needs to indicate whether the primary power source of the locomotive is providing traction or not. It is not necessary to indicate the amount of traction being applied. This is related in particular to rule B2.5 which states ‘…the primary power source of the locomotive must be disengaged from the drive wheels…’

Technical requirements/rules: Wheelset design

A recently answered FAQ states, with regard to the Maintainability Challenge, that ‘The wheelset when removed must consist only of the wheels and axle plus axle boxes, brake disks and the final part of the traction drive for example agear/pulley or sprocket where attached to the wheelset. Other parts of the traction drive including the traction motor must be disconnected from thewheelset.’

Our team have designed a gearbox where the motor and axle are integral parts, making detaching the motor from the axle impossible outside of a workshop. The motor would be disconnected electrically and removed with the wheelset for the maintainability challenge.


It is not acceptable for the traction motor to be part of the wheelset removed in the Maintainability Challenge. The only non-rotating parts of the wheelset permitted are the axelebox casings (including bearing outer race, etc.).

Separate note to this team on this point: Separate note to teams on this point: The application of this rule has not changed and no previous team has been permitted to remove a traction motor together with the wheelset as one part. Where the design of locomotives has required the removal of a traction motor initially, such as the removal of a bogie which contains an integrated traction motor, then a driven wheelset has still needed to be removed from the bogie before the time is stopped.

FAQs 2018

Challenge course: hiring track for testing ahead of the Challenge

Do you allow track to be hired for testing vehicles? We are looking for some 10 ¼” track to test our vehicle?


It is not generally allowed for teams to have access to the railway track other than for the Challenge itself. This is mainly to avoid disturbing the railway but also as it could give an unfair advantage to other teams.

However, there are many 10¼” railways where you could test your locomotive.

Challenge course: Information to aid the design process

Would you be able to facilitate us with some information about the course to aid
in our design process? Do you have a measure of the roughness of the track?

No, we do not have this information. If you would like to measure the track irregularity
or the rail roughness please contact us and we will try to make arrangements for you to
have access to the railway to make the measurement. Please note that you would need
to supply any required equipment and provide a method statement in advance.

Document submission: length of report

The design report can be no more than 12 pages, excluding appendixes, does that 12 pages include the executive summary or is it just 12 pages for the main body of the report?


There is no requirement for an executive summary. If you choose to include one, it does not have to be included within the 10-page limit but teams should note that only the 10 pages and appendices will be marked. Other material - title pages, contents list, executive summary etc. - is seen as supporting only.

Team: How many members in the team?

How many team members can a team have?

Answer: The overall team size is capped at 15. During the event the number of team members working on a locomotive at any given time cannot exceed 10.

The team member in charge of safety as required by the rules is included in the 15 team members, but not in the 10 working on the locomotive, as they are to be responsible for ensuring safe working.

Team: Sign off on testing

A Chartered Engineer is required to sign off on the testing done by the team. Can this person be a member of staff from the university?

Answer:  Yes, the Chartered Engineer can be from your own organisation.

Technical specifications/rules: Drawings - what drawings are required?

Clause 11.2.2 appears to say that we only need the top level assembly and warning label  arrangement, but 1.1.5 suggests that we need a lot more detail than the single assembly drawing can provide. The 2017 team interpreted that Improving the world through engineering to mean just the top level assembly then the next level ones, i.e. body, underframe and bogie, but the 2016 team also included many of their fabrication drawings, such as the bogie frame, control arm, traction rod etc. Can you please clarify further what drawings are required – is a top level assembly sufficient?


Please note the following Technical Specification clauses, revised so as to provide clarification on this issue:

11.2.1 Compliance matrix
The Team will produce a compliance matrix providing evidence that all technical requirements within this specification (Sections 1 – 10) have been met on a clause by clause basis. This will include a verified statement with respect to reliability testing (Clause 3.4 refers). Teams are advised to use the compliance matrix provided by the Railway Challenge Committee for this purpose. For each requirement, the matrix should briefly state how compliance is achieved in the design and refer to any relevant drawings (Clause 1.1.5 refers) which may be additional to the Design Report. If full compliance with any requirement is not achieved, details of why shall be provided.

11.2.2 Assembly drawing
In addition to drawings supporting the compliance matrix, the Team will include within its submission:
• A general assembly drawing showing the configuration of the locomotive
• A parts list / bill of materials (Clauses 1.1.1, 4.2.1 refer)
The Team will demonstrate appropriate levels of version control has been applied to the production of all drawings and other design documents.

Technical specification/rules: Energy storage assets

Section 4.1 it says:

“if refuelling comprises the replacement of energy storage assets, no individual such asset shall have a mass greater than 25kg.”

Does that mean if our power system consisted of 6 batteries each weighing 12kg, that would be within the spec?

The type of motive power utilised will be entirely at the discretion of the team, subject to the other requirements of this specification.

This rule reflects the fact that in future real world applications, it is conceivable that independent vehicles (all modes) are refuelled by storage system replacement rather than re-filling (battery, hydrogen storage etc.). The details referred to in this text (25 kg) reflect manual handling consideration. The answer is therefore yes – provided batteries are replaced individually or in pairs (2 x 12 = 24), and that the whole operation takes less than 120 seconds.

Technical specification/rules: Recuperated energy

Are we allowed to store the recuperated energy into our traction batteries and monitor the amount of energy we regenerate to make it accessible to the judges?


Yes, this will be allowed as long as the following conditions are met:

  • The amount of energy recovered must be monitored and clearly displayed and continuously visible to the judges (in line with Rules sections B2.2 and B2.4);
  • There must be a method in place to ensure than only the recuperated energy is used during the energy storage challenge (in line with rule section B2.6 and Technical Specification section 5.2);
  • The methods used to store the energy must be clear and the team must be able to demonstrate these to the scrutineers.

Technical specifications/rules: Traction Challenge - how it conducted

How is the Traction Challenge carried out on the competition weekend? How is the Traction Challenge result averaged? If it’s over a certain distance, can you confirm the distance the measurement takes place?


The Traction Challenge will be run in accordance with the rules. The positions of the points will be indicated on a plan of the railway and provided to all teams in due course.

The distance between points F and G used for the traction challenge (in combination with the noise challenge) will provisionally be approximately 100m up the gradient between the
Haven and the tunnel.

Averaging of the acceleration: this will be measured using a vibration meter which takes successive one second average measurement for the duration of the test run.

Technical specification/rules: Using innovation in wheel design or not?

When sending a wheel drawing to a potential supplier for a quote, the supplier suggested the following to reduce the cost of manufacturing the wheel:

  • Removing the 3.3 mm boss completely, keeping the wheel a maximum of 31.7mm wide.
  • The FAQs state that innovation is welcome, as long as it is compliant with the rules/tech spec/drawing with supporting documentation.

The boss is a given dimension - how far does 'as required' go? This would appear to be part of the technical spec, and non-negotiable?


We encourage innovation but would point out that it is the team’s responsibility to ensure that their design is a) safe and b) meets all of the Railway Challenge rules and specifications. This will need to be demonstrated in their design report.

In response to the specific question about the wheel we would make the following points:

  • The total width of the wheel at track level is clearly defined by drawing RC04 as 31.7 mm (+5/-0) and this is an absolute requirement for compatibility with the track system. It appears that both of the above proposals would comply with this.
  • The boss at the wheelseat is shown with a dimension of ‘3.3 mm or as required’. This can therefore be varied to suit other aspects of the locomotive design.
  • The recess between the wheelseat and the tyre is clearly labelled as ‘optional’ so can be varied to suit other aspects of the locomotive design. There may be issues around manufacturing processes and/or fatigue but that is for the team to consider.

Technical specification/rules: Wheel and axle diameter

Is just the wheel diameter is defined as 38mm or the axle? We would like to design a stepped axle that has a diameter that meets the minimum requirements only at the wheel section.

Answer:  There is no minimum axle diameter specified. It is for the teams to design the axles to suit their overall design and to ensure safe operation. Teams are reminded of the obligation to provide stress calculations, which will be the subject of significant scrutiny in areas of non-continuous section.

FAQs 2017

Entries - entering all the challenges

Would there be any possibility of entering only the design based challenges, and having different levels of competition entry as there is in the Formula Student competition? We would hope to be in a position to enter all competitions, but we are keen to assess whether this is a possibility.

Answer: Teams may enter any of the challenges and there is no requirement to enter all of the challenges although the overall result will depend on the total points scored.

Entries - multiple locomotives

This year we are hoping to enter two locomotives, but the finer details are yet to be finalised, and we may not know about whether the second locomotive will definitely be entered until around February. Would it be possible to hold off on submitting the entry application for this second locomotive until this time?

Answer: Unfortunately, due to operational considerations we can only accommodate 12 running locomotives in the 2017 final. We are hoping to be able to increase this in 2018.

Innovation challenge - what is innovation?

Our team are having a little difficulty in determining what counts as “innovative”. We have discussed this at length and are unsure whether the innovation must be new to the rail Industry or just the Railway Challenge itself. Could you clarify what counts as an innovation?

Answer:  The team may focus on any innovation in their locomotive they wish when preparing the Innovation paper but, as the guidance in the Technical Specification (section 11.3) states, the paper should outline how the innovation improves on a conventional approach and how it may be adopted by the national railway. It would therefore need to be an innovation that is new to the railway industry.

Scrutineering checklist

I was wondering if you would be able to send me a copy of the scrutineering checklist so that I can ensure that the correct safety measures are implemented on our locomotive and that we are safe to compete. Having looked through the technical specification, there are some safety requirements specified but having some form of scrutineering checklist (even if it is from last years competition) will be a big help to ensuring that we have a safe locomotive.

Answer: The 2017 scrutinising checklist is being prepared. The 2016 checklist is available.

Trailing load

2017 Railway Challenge Technical Specifications. 10.1 states that “Performance demonstration will incorporate the haulage of a trailing load of up to 1200kg”. This is an increase of 600kg compared to the 2016 requirement. Is a 1200kg trailing load to be hauled during the challenges in 2017?



Answer: Yes, as specified in the Technical Specification (section 10.1) the maximum weight of the trailing load will be 1200kg. It is not possible to give an exact value of the trailing load from 2016 as it depends slightly on the mass of the 3 people carried in the vehicle but we estimate that it was 600kg. The rules and technical specification are varied each year to introduce new challenges and to reduce the disadvantage faced by new teams.

Wheelsets: non-standard

What requirements will apply to wheelsets of non-standard construction?

Answer: We welcome innovation and non-standard wheelsets and wheels will be permitted as long as all relevant aspects of the rules and technical specification are complied with (eg back-back dimensions, spacing of active faces, maximum axle load, wheel profile etc). For non-standard materials or construction methods etc, designs will need to be supported by relevant safety analysis (component failure) and appropriate supporting calculations.

Wheelsets: removal of a 'driven wheelset'

Does an axle need to be removed from a bogie or does the bogie just need to be removed from the chassis?

Answer: As specified in the rules, a single powered wheelset must be completely removed from the vehicle. Components directly attached to the wheelset (eg brake disks, gears, axleboxes, axle mounted traction motor) may remain with the removed wheelset. For a bogie vehicle the wheelset must be removed from the bogie.

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