British Rail Class 93 (Stadler)

Historically, the vast majority of freight trains on Britain's railways have used diesel propulsion since the 1960s.[3][4] During the late 2010s, as part of wider efforts to pursue carbon neutral operations, the Department for Transport (DfT) stated its long term goal of eliminating diesel-only traction from Britain's railways by 2040, despite only 46.5 per cent of all lines being electrified.[3] However, due a lack of government support for the rail freight sector, operators have traditionally faced difficulty in justifying sizable capital investments such as new locomotives, thus large numbers are between 25 and 50 years old as of 2020.[4]

Founded in 2015, Rail Operations Group (ROG) quickly took an interest in bi-mode propulsion technology as well as high-speed freight operations.[4] The company observed that rival operators made heavy use of the Class 66, a locomotive introduced in the mid-1990s, and that this would be the base line to innovate against in the locomotive-hauled freight market. ROG opted to work in conjunction with locomotive manufacturer Stadler Rail to develop a tri-mode high powered locomotive concept, which has since been assigned the designation of Class 93. The concept was first proposed during 2018.[4][5]

It is a derivative of the Class 88 electro-diesel and Class 68 diesel locomotives, both being built by Stadler.[4][6] While the Class 88 has only limited power when operating in diesel mode, equivalent to that of a single Class 20 locomotive, thus being limited to ‘last mile’ operations in sidings or slow-speed operation on freight-only branches, the Class 93 is to have a far more powerful self-operating capability, allowing for high speed mainline operations on non-electrified lines. To achieve this, a more powerful diesel engine has been adopted, along with a series of batteries, which can generate up to double the power of the Class 88 when in diesel mode.[4]

In January 2021, ROG confirmed their order of 30 Class 93 locomotives, with the first 10 deliveries scheduled for 2023.[2]

The Class 93 locomotive has been developed to satisfy a requirement for a fast freight locomotive that uses electric power while under the wires, but is also capable of self-powered operations.[4] Accordingly, it is capable of running on diesel engines, from overhead wires, or from its onboard batteries. These batteries, which occupy the space used for the braking resistors in the Class 88, are charged via the onboard transformer or regenerative braking; when the batteries are fully charged, the locomotive only has its friction brakes available.[4] The diesel engine is a six-cylinder Caterpillar C32 turbocharged power unit, rated at 900kW, conforming with the EU97/68 stage IIIB emission standard. The batteries units are made of Lithium Titanate Oxide and use a liquid cooling solution, enabling rapid charge and discharge.[4]

The Class 93 will have a top speed of 110 mph (180 km/h), and have around 1,800 hp (1,300 kW) of usable power when running on diesel.[1] When operating under diesel/battery hybrid mode, the batteries provide the extra power to supplement the engine, greatly bolstering the locomotive's rate of acceleration.[4][7] ROG intends to pair the locomotive with a new generation of freightliner wagons that would run at comparable speed of contemporary passenger trains; by running at a maximum speed of 100 mph, it is easier to path freight trains upon a busy rail network, enabling the accommodation of more freight via its higher speeds.[4] In addition to freight, the Class 93 has also been designed to accommodate the haulage of passenger stock, including a variable-height Dellner coupling and a three-step Westcode brake in addition to its conventional two-pipe air brake.[4]

In comparison to the Class 66, the Class 93 can outperform it in various metrics.[4] In addition to a higher top speed, the locomotive possesses greater acceleration and far lower operating costs, consuming only a third of the fuel of a Class 66 along with lower track access charges due to its lower weight. ROG has postulated that it presents a superior business case, particularly for intermodal rail freight operations, while also being better suited for mixed-traffic operations as well.[4] Each locomotive has a reported rough cost of £4 million.[4]

• Dual-mode locomotive