UK operator GB Railfreight (GBRf) has formally introduced its new Class 99 dual-mode locomotive, designed to handle both electric and diesel traction across Britain’s partly-wired rail network. The launch, held on 17 July at GBRf’s Peterborough headquarters, marks the arrival of the first in a fleet of thirty units developed with rolling stock manufacturer Stadler and leasing partner Beacon Rail.
For port-related freight, the Class 99 addresses a long-standing limitation of UK intermodal rail. Container trains to and from major seaports, such as Felixstowe and London Gateway, must operate without electric traction for substantial portions of their routes, often only a short “last mile” run to a distribution hub. The new locomotive is specifically designed to run efficiently under both electric overhead wires and on non-electrified track, eliminating the need for all-diesel traction and helping operators reduce emissions and improve productivity.
Overcoming Britain’s mixed infrastructure
The UK railway network poses particular challenges for freight operators compared with many other global systems. Unlike the fully electrified freight corridors of continental Europe, the UK has a patchwork of electrified and non-electrified lines. While mainline corridors may be wired for 25kV AC overhead power, last-mile routes – including many port branches, sidings, and regional links – are not.
The branch line to the Port of Felixstowe, the UK’s busiest container port, is one such example. Though a large share of trunk intermodal traffic from Felixstowe travels on electrified routes, trains must operate under diesel power for the first and final legs of the journey. As a result, operators are compelled to use “diesel under the wires”. Felixstowe is Britain’s busiest rail freight terminal. Over thirty trains a day are dispatched – all under diesel traction.
Dual-mode solution
The Class 99 is a bespoke adaptation of Stadler’s popular Eurodual platform, modified for the UK’s tighter loading gauge, which prevents universal operation of taller intermodal railcars and precludes the practice of double-stacking. British intermodal consists are often marshalled to the maximum permissible 775m length (including traction) to compensate. The Class 99 has the power to cope with those loads, even over the undulating British terrain. The locomotive delivers 6,000kW (approximately 8,000hp) of traction under electric power and features a high-performance, low-emissions Stage V Cummins diesel engine for non-electrified operations.
John Smith, CEO of GB Railfreight (left in picture), was reluctant to be drawn on whether his company had any options placed, beyond the initial thirty units ordered, which should begin deliveries of one a fortnight from late August. “We piggy-backed on the Eurodual design,” he said. “The Cummins diesel unit, built in the UK, is the clever bit. The way it gets the power down to the track from standing start to fifty miles per hour (80 km/h) – on two and a half thousand ton trains out of Felixstowe – will be tested.” Its performance, benchmarked against the workhorse Class 66 diesel, is a key contractual requirement, he explained.
Enabling intermodal efficiency
The locomotive’s hybrid capability offers significant operational benefits for intermodal transport. In particular, it enables seamless end-to-end movement of containers from inland terminals to seaports without changing traction or relying on all-diesel operations. This is especially relevant to Felixstowe, where container trains frequently travel hundreds of kilometres inland via electrified routes but must begin and end their journey on a non-electrified line.
John Smith’s uncompromising demand that the diesel (or HVO) power unit performs on that first/last section is critical. “This new generation of locomotive is a direct answer to the challenge of decarbonising freight,” a GBRf spokesperson added. “With both renewable fuels and electric capability, our Class 99s are built for a changing network and to meet the evolving demands of our customers.”
Designed for UK conditions
With a tractive effort of 500kN and a top speed of 120km/h (75mph), GBRf says it offers a 58% reduction in emissions compared with the current mainstay of UK rail freight, the diesel-only EMD (General Motors) built Class 66, which was introduced in the late 1990s. The driver environment is a step up too, and a raft of safety and train management systems are built-in or provided for in future upgrades.
The units are being built at Stadler’s plant in Valencia, Spain. Delivery has been delayed by the recent flooding in the city, but production is back on track. Beacon Rail is funding the production of thirty units, which will be leased exclusively to GBRf. As the only operator currently committed to the Class 99, GBRf is aiming to establish a first-mover advantage in flexible, lower-carbon rail freight in the UK.
Parliamentary approval
The Peterborough unveiling was attended by senior rail officials, including Lord Peter Hendy, the UK Government Rail Minister, who has advocated for pragmatic, technology-driven steps towards decarbonisation in the freight sector.
“With robust protections for fair network access and ambitious growth targets as part of our plans for Great British Railways [the branding for a nationalisation programme in Great Britain], we’re ensuring the rail freight sector has what it needs to thrive,” said Lord Hendy. “It can continue removing thousands of HGVs [heavy goods vehicles] from our roads while delivering huge economic benefits across the country. This GB£150 million commitment to the revolutionary Class 99 [locomotive] demonstrates the confidence the rail freight industry has in its future.”
Incremental change for a fragmented network
The Class 99 arrives at a time when UK rail freight is under increasing pressure to decarbonise while continuing to serve a complex and ageing infrastructure network (as reported by RailFreight.com). Full electrification of key freight corridors, including access to ports, remains years away, notwithstanding the complexity of handling electric trains within a modern intermodal port, where overhead wiring would hamper container loading. As such, the Class 99’s dual-mode functionality represents a practical and immediate step toward net-zero emissions goals.
By bridging the gap between electrified trunk routes and non-electrified terminals, the Class 99 offers a scalable model for hybrid traction. Other markets are facing similar transitional infrastructure challenges. The Class 99 units could potentially inform traction strategies in parts of Europe, Asia, and the Americas where electrification remains at best incomplete, and in many cases, a mere pipe dream.