COMMENTARY: We need a more sophisticated discussion on the rail versus domestic flights climate issue

In April this year, as part of climate measures to reduce carbon emissions, French MPs voted to ban flights on domestic routes that can be travelled by direct train in less than two-and-a-half hours. This had been reduced from a previous recommendation that proposed the limit at four hours, following a French government bailout to Covid-hit Air France. In the UK, and picked up by the national press, environmental pressure group Campaign for Better Transport (CfBT) is now calling on the government to ban domestic flights where the equivalent train journey is under five hours. Calls for bans of domestic flying have become frequent and the general public perception, driven by the constant criticism of environmental NGOs, is that domestic flying is amongst the most climate destructive activities we humans can make. But how bad is it really and when and where do the alternatives come into play, questions Andy Smith, Head of Sustainability Strategy at Scottish regional airline Loganair.

The objective here is not to argue for one mode versus the other, but to understand the true carbon and financial trades of the travel choices consumers and planners face, rather than relying on the very crude national averages used to make sweeping generalisations.

Firstly, what is the scale of the problem being described: the amount of emissions from UK domestic air travel where there is a five-hour equivalent rail journey?

Using OAG data, I found 127 unique UK domestic city pairs currently served by air. Of these only 46 pairs (36%) had a viable rail route given that the majority of UK domestic air services cross water. Of these 46, only 16 routes (13% of the total) met CfBT’s requirement of five hours by rail and some of these only just on occasional services. One of the key claims of rail proponents is that rail has by far the lowest CO2e per passenger km of any form of travel. The government (BEIS) statistics support this claim but do so by taking a blended average of electric and diesel-powered trains.

Given how widely domestic air travel is condemned, most people are surprised to learn that emissions from the rail network are almost double that of all UK domestic air services (3.0 MtCO2e for rail and 1.6 MtCO2e for domestic air) and both of these are dwarfed by the equivalent emissions of road vehicles at 122.6 million tonnes of CO2e per annum. Over half of rail emissions come from diesel trains and although the majority (80%) of rail journeys by kilometre are made by electric train, only 42% of the UK’s rail network is physically electrified.

The electrified network, apart from the East and West Coast mainlines, is concentrated in the commuter belt around London and these commuters account for the majority of UK rail traffic. Outside of the mainlines and the London region, electrification is sparse and patchy and of our 16 “doomed” domestic air routes, only seven can be operated by purely electric train services. Nonetheless, diesel services can connect with electric services to allow efficient travel but this is not necessarily how services are timetabled.

Is there any significant difference between diesel and grid-powered electric train emissions? In short, yes. There are only very opaque figures reported by the rail industry and none on the fuel use per train service or per kilometre travelled by traction type but some high-level figures are available. Taking the regulatory Office of Rail and Road’s 2019 figures of 66.7 billion passenger kms travelled and the 80% electrification figure, we get an estimate of 13.3 billion non-electric train RPKs. Against the 1.7 MtCO2e direct emissions from rail, this gives an estimate of 0.127 kg CO2e per diesel rail passenger km. The equivalent direct CO2e figures quoted by BEIS for domestic air travel are 0.130 kg CO2e per passenger km – so close as to be insignificant.

The other 1.3 MtCO2e from rail is the impact of the electrical consumption of the network and uses the grid carbon intensity average. As the national grid’s renewable power generation increases, so the carbon intensity of electrified rail travel reduces. So far so good. However, the structure of the grid means that when demand peaks, fossil-fuelled production is spun up meet the requirement. Any marginal load on the grid is directly driving fossil fuel consumption and conversely any reduction in demand would directly reduce fossil fuelled emissions.

The point is not to argue that the rail electric system should be disconnected from the grid but rather to indicate that all electrical demand is fundamentally equal and at peak times, regardless of whether a train operating company has contracted only green power, marginal electrical train consumption means marginal generation, which in the UK means fossil fuels being burned – coal or gas.

However, for the sake of this analysis we shall assume that all 16 domestic air routes are replaced by electric trains with virtually no emissions from our hypothetical greened grid.

The routes are:

Aberdeen-Newcastle
Aberdeen-Teesside
Birmingham-Edinburgh
Birmingham-Glasgow
Bournemouth-Liverpool
Bristol-Teesside
Cardiff-Southampton
Edinburgh-London
Exeter-Manchester
Glasgow-London
Humberside-Newcastle
Leeds Bradford-Southampton
London-Manchester
London-Newcastle
London-Teesside
Manchester-Southampton

Using the Eurocontrol small emitters tool and the OAG timetable for October 2021, I estimated the total direct emissions of all carriers on these routes at approximately 112,500 tonnes CO2 per annum. Whilst this sounds like a lot, it is less than 0.1% of annual UK transport emissions, which seems hardly worth the airtime and print space given to CfBT’s proposal.

Over 75% of the emissions from the list of flights above come from just two routes, Edinburgh (EDI) and Glasgow (GLA) to London. Flights are operated into every major London airport – LHR, LCY, LGW, STN and LTN – and clearly serve not just the point-to-point traveller but also connect both EDI and GLA to the primary UK long-haul networks which operate out of LHR and LGW. We shall ignore the importance of such connections and also assume that in the interests of reducing our national emissions, the benefits of travellers being able to day-return via air must also be sacrificed. How would the rail network cope with the additional traffic?

The schedules for EDI provide approximately 3 x E190 and 5 x A320 aircraft on the route per weekday in each direction during peak morning hours. For GLA the equivalent is 2 x E-190s and 5 x A320s, which equates to approximately 1,200 and 1,100 seats in each direction respectively. The Pendolino and IET sets which run on the West (WCML) and East (ECML) Coast rail mainlines respectively seat approximately 550-650 passengers and so two additional sets would be required in each direction on both the WCML and ECML to provide a minimum comparable capacity on the core GLA and EDI services.

Combined with the cancelation of the other services in the list, this is increased to three sets in each direction on both WCML and ECML, for a total of 12 ‘diagrammed’ additional units. In practice, this would require at least 16 additional sets to be acquired with a nine-car IET costing approximately £21.6 million, making a CAPEX of around £345 million ($475m) in rolling stock. But there is no need to purchase the extra train sets because the WCML is currently at capacity, with the May 2020 timetable declaring no viable additional paths possible without impacting punctuality performance, so the addition of six peak hour trains is not an option. The ECML is less constrained but unlikely to be able to provide capacity for more than one or two additional peak time trains for the entire length required. The high-speed HS2 rail line, when it comes online, will relieve some capacity on the London to Birmingham leg of the WCML, but will not provide any capacity north of Birmingham, even if future phases are approved, until the 2030s.

A frequently ignored element of carbon emissions from rail travel is the carbon cost of the 100,000 tonnes of steel and 300,000 tonnes of concrete used annually to maintain the network. This is most striking in HS2, where the carbon cost of the infrastructure on the project is estimated to be between 8 and 14 MtCO2e – nearly 10 times the annual emissions from all domestic air travel in the UK, and this is before a single train has been run between London and Birmingham.

To reiterate, there are undoubtedly carbon savings from electrified rail versus flying specifically. But they may not be the cheapest, quickest or most practical way of decarbonising our national transport system. Even if the rail capacity existed to replace the air services, as CfBT demands, the capital cost of £350 million at a 10% return is generating carbon savings at around £350 per tonne of CO2e. A better discussion would be about how we could improve on this figure.

If we are to make genuine progress in reducing the carbon intensity of our transport network we need less stunts, less deriding the green credentials of competing modes of travel and serious, practical discussions about where and how we can cut emissions from the UK’s public transport network the hardest and the quickest.

Top photo: Airbus/Avanti

Views expressed in Commentary op-ed articles do not necessarily represent those of GreenAir.