Shifting freight from road to rail provides the best short-term route to reducing freight’s carbon emissions.

That’s because an HGV produces four times more carbon emissions than even a diesel freight train. The difference is even more stark for an electric freight train.

As the Department for Transport notes in its Transport Decarbonisation Plan: “The modal shift of freight from road to rail would not only lead to a reduction in GHG levels, but also reduce congestion and noise pollution.”

Such a shift might be easier said than done if the results of a joint investigation by Network Rail and Highways England are anything to go by. They have been looking at the corridor between the Solent and the Midlands. That’s chiefly the A34 and the mix of lines between Southampton, Basingstoke, Reading, Didcot and points north.

The A34 is Highways England’s busiest road that isn’t a motorway. The joint report notes that “the rail network is heavily congested along this corridor for both freight and passenger services.”

Hence its recommendation that NR’s Wessex team investigates how to improve rail capacity. Meanwhile Highways England is under pressure to cut congestion. Between them they plan to look for potential sites for more railfreight terminals and interchanges. And they will look for traffic that is better carried by rail than road.

Analysis so far has found that food and drink is a major commodity on the corridor. NR and HE plan to investigate further what barriers stand in the way of carrying more by rail. The same applies to chemicals.

Freight electric spine

The corridor featured prominently in the DfT’s High Level Output Specification back in 2012. It was earmarked for electrification as part of what was dubbed the ‘Electric Spine’. Railfreight companies gave it a lukewarm response and continued to press for Felixstowe-Nuneaton’s wiring. They didn’t want what the DfT was offering and DfT wasn’t willing to entertain their alternative. The result continues to be diesels plying both routes.

Nevertheless, there’s some optimism in the joint report that rail could pick up more traffic. It’s hard to see otherwise from the road-rail traffic ratios which between the Solent and the East Midlands lie 95%/5% in road’s favour. For the West Midlands, it’s slightly better at 79% road, 21% rail. Only up to North West England does rail take the bulk with its 53% share. 

On average there are 4,000-6,000 HGVs on the corridor every day while 2019/20 saw 9,400 intermodal trains (equivalent to 300,000 HGVs). According to the report, there’s potential for an extra 5-20 trains per day compared with 2017’s 23 trains per day. That’s if NR can convince DfT to fund infrastructure improvements.

I’ll come back to infrastructure improvements but before we leave mode shift, there was another line from DfT’s decarbonisation plan that caught my eye.

“Working alongside transport providers, we will look to influence more sustainable travel behaviours by providing advice and guidance on the messages that are most effective in driving behaviour change towards use of sustainable transport. Research suggests the most persuasive factor in transport mode-switch decisions are stories of others who have made similar switches.”

I’ve taken those words slightly out of context. They come from the plan’s section about personal transport choices in which DfT talks about car-sharing, ‘mobility as a service’ and things like e-scooters. But I reckon they apply just as much to freight. Change from road to rail can be helped by tales of success and by hearing stories from those who have switched. After all, it’s people that make transport decisions; containers don’t have a say.

Coming soon

Anyway, back to infrastructure. DfT’s plan hints at some decisions when it says: “We will announce further electrification projects shortly, ensuring the lessons of previous schemes are learned and that individual projects deliver value for money.” Quite what ‘shortly’ means is anyone’s guess.

A few pages later DfT says: “Short ‘infill’ electrification projects could quickly deliver benefits and enable rail freight operators to immediately switch services over to electric traction.

“This would reduce costs as electric locomotives cost less to operate and could also reduce journey times as electric traction provides quicker speeds and better reliability than diesel fuelled services. 

“By filling in electrification gaps to key ports and terminals, we can open new opportunities for electric, cleaner, greener rail freight journeys.”

Are we to finally see the gap between Ipswich and Felixstowe wired? Or the three miles to London Gateway? Or those awkward gaps in West London? Let’s hope so.

Joint freight working

That would be a start but what’s really needed is for freight’s needs to be woven into any plans for electrifying passenger routes. Extending the Midland Main Line’s wires northwards from Market Harborough raises the prospect of aggregates from Mountsorrel heading to London as electric freight. But only if the specification includes sufficient power in the wires to cope with heavy freight.

That’s one of the lessons of the East Coast Main Line where some bi-mode trains must run on diesel under the wires because power supplies are too weak. This flaw prompted Direct Rail Services to deploy a Class 68-Class 88 combination when working trains diverted onto the ECML by West Coast Main Line engineering work earlier this year.

They packed a punch. The ’68’ provided power from its 3,800hp (2.8MW) Caterpillar diesel for those weakly wired sections. Meanwhile the ’88’ contributed a more meagre 940hp (0.7MW) on diesel. When Network Rail’s catenary could take it the ’88’ could switch to its 5,400hp (4MW) electric mode. And as I understand it, that didn’t mean turning the ’68’ off which made for a quick getaway from speed restrictions.

Bridging gaps

In essence, the DRS combo was a super bi-mode. It accepted that two locomotives on the front of a freight train is a neat way of creating flexibility. Consider if one of those locomotives contained batteries and the other was a straight electric. The result would be a pairing capable of bridging weak sections or gaps in catenary. The batteries could also cope with unwired terminals. They might be charged by regenerated electricity during braking or from overhead wires.

The concept extends one put forward by RSSB in a report into railfreight decarbonisation last summer. It worked from a standard intermodal journey that it defined as 230 miles with a 1,500 tonne trailing load. This needed a maximum power of 2.4MW and consumed 8.9MWh over its 6.5-hour journey.

To put some perspective on those figures, a Class 66 fuel tank contains the equivalent of 19.8MWh of energy. The batteries on the Class 379 passenger train tested by Network Rail a few years ago contained 0.5MWh. To carry sufficient batteries for a single standard intermodal journey would need three tenders weighing 252 tonnes using current LTO battery technology, according to RSSB. It suggests this might come down to 65 tonnes and one tender by 2040 as technology develops.

Just add batteries

Those figures explain why railfreight operators currently consider batteries as only good for terminal work or perhaps last-mile haulage. That could change so there’s a prospect of batteries playing a part in removing railfreight’s need for diesel. But prospects don’t solve today’s problem for which the only effective answer is electrification.

Which creates a tricky dilemma. 25kV electrification covers only a third of the network. Extending it will take years and those years might produce effective alternatives such as batteries. Yet for every year that government delays electrification decisions the annual mileage to be installed increases, unless government lets its decarbonisation targets slip.

DfT recently released a report written last March by Mott Macdonald that covered this problem as it laid out roadmaps towards transport decarbonisation. It notes that Network Rail’s electrification report last year talked about annual rates of 435 single-track kilometres (stkm) between 2021 and 2050, with a peak rate of 691stkm. Mott’s report suggest this is “at the ambitious end of realistic”. It adds that it takes seven years to install a connection point to the National Grid.

The report warns that if electrification cannot proceed at sufficient pace then more emphasis will need to fall on batteries, hybrid battery-electric and hydrogen. It notes a need to accelerate development of battery-electric hybrids.

Anyone fancy developing a mainline battery locomotive to work in combination with a straight electric?

A version of this article first appeared in RAIL Magazine on July 28 2021. See more at

By Philip Haigh

Freelance railway writer, former deputy editor at RAIL magazine - news, views and analysis of today's railway.