Over the past 20 years the railway has adopted many new technologies on modern passenger trains and infrastructure equipment which have provided significant benefits. However, rail freight has seen little new technology. Most freight trains are hauled by a diesel locomotive introduced in the 1990s. Freight wagons, with no electrical supply, have a maximum speed of 75mph, the speed of the original freightliners when they were introduced in the 1960s. Freight trains are also governed by an operating regime which is little changed since British Rail days.
Though there is an active rail freight research and innovation programme, there are significant opportunities to transform the rail freight sector. To learn more about the potential for such a transformation, Rail Engineer was glad of the opportunity to speak to Karl Watts who led the introduction of the tri-mode Class 93 locomotive when he was chief executive of the Rail Operations Group.
In his current role as founder and managing director of Railmotive, Karl has produced two papers ‘Rail freight – a path to the future’ and ‘Intermodal Rail freight – a vision of the future’ which form the basis of this feature. The latter paper considers an intermodal freight train operation set in 2032 which takes advantage of the latest operational and technical innovations.
XM12 in 2032
XM12 is imagined to be an intermodal service from Thames Gateway to Trafford Park which operates in a ‘variable speed’ intermodal path which takes account of a new train classification system. Leaving Thames Gateway, it runs as a Class 6 train to reflect the low speed of the infrastructure. From Wembley, it runs as a Class 4 train to reflect its average speed of 60mph. This gives it a higher priority than Class 5 stopping passenger trains that average 42mph. Along the busy Trent Valley corridor it runs as a Class 3 train to reflect its 90mph maximum speed.
By 2032 the rail industry will have a new AI-powered timetabling system to maximise network utilisation and ensure trains are pathed according to their performance. Train prioritisation for timetabling and regulation will also use a value-based system rather than a system that was introduced in the 1950s in which all passenger trains have priority over freight trains. The difference between these two systems is shown in Table 1 (left).
A comparison of West Coast Main Line (WCML) slow line running times shows the importance of taking account of average train speed. Although its maximum speed is 110mph, the average speed of a stopping train between Tring and Harrow is 42mph. Yet the average speed of an intermodal train is around 60mph. Thus, the Class 4 train should have a higher priority than the Class 2 train. Furthermore, an intermodal train conveying time-sensitive goods worth £20 million could be considered to have more economic value than a lightly loaded passenger train.
XM14 is hauled by a high-powered electric or multimodal locomotive as by this time almost all diesel freight locomotives will have been withdrawn. The container flats are 90mph, light weight, articulated, single axle wagons with independently controlled wheels which provide a self-steering vehicle. The wagons can also double the train’s traction power for short periods when accelerating or climbing gradients as each wagon has its own motor powered by a battery which is charged when it brakes.
With such high performance, XM12 can make three end-to-end trips between Thames Gateway and Trafford Park each day running for 19 hours a day – a 90% increase in the train utilisation levels in 2025.
XM12 is operated by the fictitious company Transmodal which is a global freight logistics company specialising in multi-mode freight transport. Rather than trade directly with freight companies, it trades with a logistic company offering a ‘port-to-door’ solution which maximises rail traffic and uses road transport for last-mile deliveries.
Although Railmotive’s vision is for a transformed intermodal freight operation, much of it relates to other freight train operations. The remainder of this feature considers current technology and developments which could deliver this vision.
Electric freight
Despite a large proportion of the core freight network being electrified, in Britain a mere 2.8% of rail freight traction energy consumption is from electricity. Hence few freight trains benefit from electric traction. As electric locomotives have typically twice the power of a diesel locomotive (electric Class 92 – 5MW, diesel Class 66 – 2.2 MW), they can haul heavier, faster trains.
As shown in the graph, a Class 66 diesel locomotive with a 1,235-tonne intermodal train slows from 60mph to 20mph as it climbs the five-mile 1 in 70 gradient to Shap summit, whereas 2 x electric Class 90 locomotives remain at their maximum speed of 75mph throughout this climb. This illustrates the benefit of electric freight traction on the steeply graded lines between Lancaster and Glasgow.
However, it is not just the northern fells for which diesel freight is problematic. On the gentle 1 in 300 climb between Willesden and Tring, a Class 66 hauled intermodal freight can manage typically 45mph. This compares with 75mph for an electrically hauled freight which is a higher average speed than the stopping trains which enables electrically hauled freight to precede such trains without delaying them.
Although electric freight currently has higher fuel costs than diesel freight, Karl considers this additional cost is far outweighed by the savings from improved asset utilisation and reduced train crew cost that faster electric freights provide. Moreover, faster electric freight trains offer better use of the network as a slow diesel freight takes up two train paths. Surprisingly, the track access regime does not incentivise the provision of extra paths through the use of electric traction.
One reason for the lack of electrically hauled freight in the UK is the need for infill electrification on freight routes to provide electric haulage for the complete route.
The provision of an all-electric WCML freight service would require power supply upgrades. However, the total power capacity these provide could be minimised by intelligent OLE Supervisory Control and Data Acquisition (SCADA) which, for short periods, could automatically reduce peak locomotive traction demand when there are multiple electric trains in the same section.
Class 93
On 15 January 2021, Rail Operations (UK) Limited signed a framework agreement with Stadler for the supply of 30 Class 93 tri-mode locomotives. The first of these arrived in the UK in 2023. Ride and static evaluations have now been completed and, after successfully completing initial tests with 400 tonne loads over Shap summit, a 2,000-tonne load test was imminent at the time of writing.
As described in Issue 189 (Mar-Apr 2021), the Class 93 is a tri-mode Bo-Bo locomotive. In electric mode, it can run on 25kV AC overhead lines with a power of 4,000kW. Its Caterpillar C32 engine has a nominal power of 900kW which can be boosted by 400kW for short periods (e.g., while accelerating or going up gradients) by its battery pack when operating on non-electrified lines. Shunting operations can also be powered by the batteries alone.
The capabilities of the Class 93 are shown by a comparison of its tractive effort curves with other traction. These curves show how the pulling force of all forms of traction diminishes with speed as power is the product of force and velocity. Diesel traction has a far greater reduction of tractive effort at speed than electric traction. For example, a 2,460kW heavy-haul Class 66 diesel locomotive has a particularly high tractive effort at slow speeds, yet at 40mph it only has 30% of its low-speed pulling power.
In electric mode, the Class 93 has twice the tractive effort of the Class 66 at 75mph. With just a 900kW diesel engine, the Class 93 can manage 60% of a Class 66’s tractive effort at 75mph.
Another new electric locomotive that can operate off the wires is the Class 99 Co-Co locomotive described in Issue 212 (Jan-Feb 2025). Though such locomotives are a solution to the lack of freight infill electrification, the additional costs of such traction over conventional electric locomotives may well be greater than infill electrification.
With hundreds of diesel locomotives requiring replacement in the next decade, rail freight companies would no doubt appreciate sight of a long-term electrification strategy.
Advanced wagons
Railmotive’s intermodal freight paper envisages a train of 12 x three-vehicle articulated sets formed of 10-tonne twin-axle platforms carrying 40-foot, 31-tonne containers at 90mph. Traditionally, such wagons have a 60-tonne payload but in practice the maximum weight of a container on rail is that of the maximum that can be carried on an HGV, which is 31-tonnes. As the wagons are designed for this lower payload they can have single axle suspension, which eliminates the need for bogies and so offers significant weight savings.
It is also envisaged that these wagons would have intelligent on-board systems including wheel flat prevention, brake monitoring, vibration sensors, condition monitoring, GPS, and data transmission like those on the iWagon as reported in Issue 206 (Jan-Feb 2024). However, rather than being powered from axle generator, these intermodal wagons would be powered from the locomotive jumper via a cable throughout the train. As intermodal trains operate in fixed formations, coupling each wagon’s cables together is a more appropriate solution than axle generators.
On the European mainland, it is proposed to introduce Digital Automatic Coupling (DAC) by 2030 for the provision of intelligent wagons and more efficient coupling of freight trains. However, an RSSB report (T1264) estimates that fitting DAC to around 14,000 wagons in the UK would cost £600 million. It concludes that autocoupling offers little benefit as ‘block trains’ are the norm in the UK and that DAC’s main benefit is providing wagons with an electrical supply for which there are more cost-effective solutions.
Railmotive also envisages that wagons will use the ActiWheel system which is being developed by SET. This independently controls each wheel to provide a self-steering vehicle which significantly reduces track forces. This system monitors wheel distance from the track centre then calculates the speed of each wheel for the train to remain centred. It has a permanent magnet synchronous traction motor within the monobloc wheel so does not need a transmission system. Furthermore, as its electric braking works down to zero speed, it does not require friction braking.
This system was successfully demonstrated on a Class 230 unit in 2019. However, introducing such a new radical arrangement will require a robust safety case.
A significant potential benefit of the ActiWheel system is that it could more than double a freight train’s traction power for short periods of time when climbing steep gradients or accelerating.
This could be done by powering the ActiWheel motors by batteries which are charged when the train brakes.
Logistics
The Railmotive paper considers how the fictitious global freight and logistics transport company Transmodal offers multi-mode freight transport by trading with a logistics company which is not rail specific as its model considers all container transportation modes to deliver ‘port-to-door’ at any one moment in time. Nevertheless, this is expected to ensure that every train will convey a minimum of 90% payload. Furthermore, this is likely to facilitate the operation of services from ports and terminals with currently unviable low container volumes.
This type of operation is that used by iPort Rail. As reported in Issue 201 (Mar-Apr 2023), a Railway Industry Association (RIA) Unlocking Innovation event in Doncaster focused on rail freight and included a visit to iPort Rail which was opened in 2018. As explained at this event, the challenge is to bring transport elements together for road hauliers to shift their operations from long haul to final mile. For them, using rail freight for long haul with a few short HGV journeys per day is more profitable than long haul HGV operations.
To do this, iPort Rail is working with third party logistics provider Eco2loco to fill the space on its trains and has developed RAILX container booking system to do this. This enables customers to instantly book a container on a train as trainline does for passengers.
Planning tools
Around a fifth of freight train movements are Very Short-Term Plan (VSTP) movements. Finding the paths for such moves is a cumbersome process as the required data is in various documents that are not well integrated. This is dependant on the experience and skills of planners and has long lead-times making it more difficult for the freight industry to compete with a more dynamic road freight industry. To address this problem, University of Hull’s Logistics Institute has developed NR+ which digitises various documents such as Sectional Appendix, Load Books, RT3973 library, and engineering access statements into a single efficient graphic database. In essence this provides a ‘Google Maps’ for freight train planning.
The University of Hull’s Logistics Institute has also developed the Rail freight Energy and Emissions Calculator (REEC) which uses data from its NR+ system together with other information such as gradient profiles to assess the duration, energy consumption, and emissions of individual freight train moves. It does so by breaking the route into 10 metre segments to which an algorithm is applied. This is based on theoretical equations which have been adjusted and validated using On Train Monitoring Recorder data from hundreds of journeys.
NR+ and REEC are now managed by the University of Hull’s subsidiary Lampada Digital Solutions which, in 2023, won a Network Rail tender to develop the Digital Freight Train Loads book which now has 600 active users.
RSSB research
Much of RSSB’s freight research supports Railmotive’s vision for 2032. Examples of this are:
Impact of Heavy Axle Weight on infrastructure (Report T1265). In partnership with the University of Southampton, a model was developed to assess future route options for heavy axle weight rail freight traffic on the network.
Revision W10 and W12 freight gauges (T1327). These gauges were not suitable for some wagon-container combinations for which costly and time-consuming analysis of individual freight vehicles were needed to assess the safe use of new containers on specific trains. This result increased the allowable wagon and container combinations that can run on W10 and W12 cleared routes such as those possible with lower wagons that the ActiWheel system makes possible.
Optimising freight sectional running times (T1301). This project provided more accurate definition of the maximum trailing load for a freight train by considering a locomotive’s available power and the train’s resistive forces. In all cases studied, it was found that sectional running times (SRT) were too conservative and that heavier freight trains could be run.
Coupler strength limitations of freight train loads (T1256). The allowable loads for different types of couplers were specified by British Rail in 1969. This research re-examined the engineering principles behind Network Rail’s coupler ‘traction rating’ designation used to set the loading limits and found that they could be re-calculated to allow up to an extra four wagons per train.
Efficient freight train regulation (T1263). This report was completed in March 2023 and quantified the impact of the current regulation regime, noting that no account is taken of the energy or environmental impact of stopping freight trains. It also produced a good practice guide for timetable development which showed that there was significant potential for improved regulation to reduce freight train journey times.
Achieving the target
In 2023, rail freight carried 16 billion tonne-kilometres of freight which is 10% of UK domestic freight. In its recent report, Rail Partners considered that this contributes £2.45 billion to the UK economy each year. Furthermore, as well as producing 76% less CO2 per tonne than road haulage, rail freight’s societal costs which include congestion, noise, and accidents are a fraction of those of road haulage.
Yet these benefits are not captured in freight pricing. The Rail Partners report shows that rail freight’s energy and track access / road levies charges are respectively 22% and 113% higher than road haulage.
In December 2023, the previous government set a rail freight growth target of 75% by 2050 which is 2.3% per annum. Given rail freight’s higher costs and network capacity constraints, this is a challenging target. However, as this feature shows, with modern technology, electric traction, and freight-friendly operating practices, it should be possible to achieve and exceed this target, with trains such as XM12 offering an even more efficient service.
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