Imagine breathing cleaner air at one of London's busiest train stations. That dream is closer than you think, as diesel trains are finally being phased out of St. Pancras! But the journey to get here has been anything but smooth.
For years, the area around King's Cross and St. Pancras was plagued by thick smoke and fumes from railway fossil fuels. These once-grimy stations have been transformed into modern hubs, and soon, even the last vestiges of diesel pollution at St. Pancras will disappear. East Midlands Railway (EMR), which connects London to cities like Derby and Sheffield, is scheduled to run its final diesel-powered service from the station by the end of 2026.
This marks a significant milestone for St. Pancras, though it's an achievement that's been delayed and more challenging than anticipated. The arrival of EMR's new, cleaner Aurora trains, manufactured by Hitachi, is years behind schedule. Simultaneously, plans to fully electrify the Midland Main Line, the track these trains will use, have been scaled back. And this is the part most people miss: it's not just about the trains, it's about the infrastructure supporting them.
According to Will Rogers, the managing director of EMR, the Aurora trains will significantly improve the environment at St. Pancras. He highlights the anticipated reduction in both noise and emissions. The new fleet is designed as bi-mode trains, meaning they can operate on electricity in the southern part of the route and switch to diesel power further north. Where the trains can use electricity – up to just south of Leicester – carbon emissions can be reduced by an impressive 66%, according to Rogers.
On a broader scale, rail travel generally offers a more environmentally friendly alternative to other modes of transportation. Trains consume less energy per passenger compared to cars, have a far smaller carbon footprint than airplanes, and often produce fewer harmful emissions. But here's where it gets controversial... Even with these advantages, rail travel isn't entirely green.
Approximately 70% of Great Britain's passenger train fleet is electric, and about 8% are bi-mode. However, only 39% of the total railway route length is electrified. This electrification is primarily concentrated in the more densely populated southeast of England, where the majority of train journeys occur.
The Rail Delivery Group's emissions calculator shows that around 94% of journeys are greener per passenger by rail than by a petrol car (assuming an average car occupancy of 1.6 people). However, this balance shifts when comparing a battery-powered car to a diesel train. It raises a key question: are we investing in the right technologies for a truly sustainable future?
Electrifying the railway has been a long-term goal for both the government and the industry. However, the cost and execution of recent projects have caused policymakers to reconsider their approach. The Great Western main line electrification, for example, was eventually completed in 2020, but with significant sections cut short. It also experienced years of delays and a budget that tripled in size. And this is the part most people miss: it's not just about the trains, it's about the infrastructure supporting them.
This kind of risk may not be appealing to a government focused on balancing the budget. Many were surprised and disappointed when the Midland main line electrification was halted south of Leicester last year.
Rogers takes a diplomatic stance, acknowledging the difficult choices involved but expressing a desire for further electrification. He points out that the new EMR trains cost £400 million, and that combined with the £1.5 billion invested in the main line electrification, it represents a significant investment.
Electrification projects are ongoing elsewhere, including the TransPennine route east of Manchester and the nearly completed South Wales Metro. However, for now, cities like Leicester and Derby, the proposed home of Great British Railways, will face the same frustration as Bristol on the Great Western line: brand new main-line trains running on diesel within their city centers, despite having traveled most of the way from London on electricity.
The "dieselgate" scandal and London's ULEZ (Ultra Low Emission Zone) have highlighted the health risks associated with nitrogen oxide (NOx) emissions from diesel cars. But the immediate NOx exposure from older trains – for both passengers and those waiting at stations, as research from the Rail Safety and Standards Board has demonstrated – can be higher than the air pollution levels on a busy road.
In London, most main line stations have already eliminated diesel trains. At Euston, Avanti's transition to fully electric trains was completed a year ago, with a few bi-mode trains switching to diesel at Crewe, 145 miles away, for routes into north Wales. A small number of diesel trains operate from Waterloo to branch lines, and King's Cross hosts 10 daily services run by Grand Central, whose order for tri-mode hybrid trains will eventually allow its fleet to run solely on electricity within the capital.
The main exception is London Marylebone, which is not electrified. Its lines through the Chilterns are constrained by aging infrastructure, bridges, and tunnels, making full electrification prohibitively expensive, if not impossible.
A solution similar to what is being implemented in South Wales, and with potential for Northern's network and the future East West Rail project connecting Oxford and Cambridge, is a combined approach: selective track upgrades in accessible areas combined with new train technology. Network Rail's route director, Denise Wetton, says they are exploring battery-hybrid trains and partial electrification all the way to Birmingham.
The potential of fast-charge technology was demonstrated by a GWR test, which set a world record by running a train 200 miles on a single charge this summer. Simon Green, GWR's engineering director, described it as "a bit of fun," but emphasized the serious point that investment in battery technology is crucial for replacing their aging diesel fleet.
While overhead lines are the preferred solution, batteries could bridge the gaps where installing wires is too difficult or costly. For GWR trains traveling to the far southwest of England and Wales, these stretches could be about 60 miles between charges. Green believes the test provided "clear evidence that this is a viable and exciting solution for the future of our railway."
Chiltern's MD, Richard Allan, believes there will be a "compelling case" for improved technology. In the meantime, the line will introduce a new fleet of more efficient diesel trains and mitigate emissions by increasing the proportion of hydrotreated vegetable oil – or recycled chip fat – from 7% to 20% of the fuel used.
As EMR's experience shows, ordering, building, testing, and deploying new or improved trains can take many years. However, it may still upgrade rail travel faster than some other solutions, as commuters in the Chilterns can attest. Looking out from a new Chiltern train at the construction of the HS2 high-speed rail line near High Wycombe, Allan remarks, "They've had to watch HS2 being built – now they have some benefit locally too."
Meanwhile, the Department for Transport is collaborating with Network Rail to develop an updated electrification plan and a new rolling stock strategy. The previous goal of eliminating all diesel trains from the railway by 2040 is currently under review.
A spokesperson stated, "We are committed to electrifying and decarbonising our railway, and our approach will focus on the most cost-effective schemes that make the greatest difference as quickly as possible."
The better trains on their way:
East Midlands Railway:
The £490 million fleet of Hitachi-built Aurora trains has arrived three years late, but passengers on the intercity route connecting Derby, Leicester, Sheffield, and Nottingham to London will benefit from more seats and space, as well as a smoother, quieter ride. Wheelchair users will have access to first-class seating. And special German-made glass promises to improve mobile phone and data connectivity within the carriages.
Chiltern Railway:
The new fleet of 13 Mark V trains, acquired nearly new from TransPennine Express, may not be electric but are certainly an upgrade from the 50-year-old trains they are replacing. They will provide an additional 10,000 seats per week, as well as amenities such as Wi-Fi, air conditioning, and accessible toilets.
Piccadilly Line:
The Piccadilly Line is already electrified, but its new fleet, constructed from lighter materials and designed for energy efficiency, should consume 20% less electricity in service, according to Transport for London. Most passengers will appreciate the increased headroom, air conditioning, and walk-through carriages. The trains are expected to enter service between late summer and December.
What do you think? Is focusing on electrification the best path forward, or should we be exploring alternative technologies like battery-powered trains more aggressively? Are the delays and cost overruns of electrification projects a sign that we need a new approach? Share your thoughts in the comments below!
