At the beginning of the month, I published a piece in Voice of San Diego calling for medium-speed rail investment in the Los Angeles-San Diego corridor, centering electrification. This was discussed in a 500-comment thread on California HSR Blog, in which area rail activist Paul Dyson ripped into my plan, arguing (among other things) that electrification is costlier and less useful than I think. Instead of reopening the debate on that particular corridor, I want to discuss a more general set of guidelines to when rail lines should be electrified.
I haven’t said so in these exact words, but I think North American rail authorities and activists underrate electrification. As a result, I find myself persistently prescribing electrification and defending it when it’s already on the table, even as I attack other rail investments as wasteful. On social media and in blog comments I find myself having to constantly explain to people that no, a $20 billion New York regional rail plan should not use dual-mode locomotives but rather spend $250 million on New Jersey-side electrification.
A year and a half ago I wrote about why small, dense countries should fully electrify. The reasons laid out in that post are included in the guidelines below, but there are some additional circumstances justifying electrification.
Narrow stop spacing
Each train has a stop penalty – a total amount of time it loses to making each stop. The penalty is based on dwell time, line speed, and train acceleration and braking performance. If the line speed is 130 km/h, then the penalty excluding dwell time is about 35 seconds for a FLIRT and 80 seconds for a diesel GTW. This 45-second difference per stop is the same if there is a stop every 3 km or if there is a stop every 50 km.
Stop spacing is narrower on commuter lines than on intercity lines, so electrification usually starts from commuter rail. The first mainline electrification in the world was in Paris on the commuter lines serving Gare d’Orsay; subsequently the commuter lines in Paris, London, Tokyo, Berlin, New York, Philadelphia, and other major cities were wired. In many of these cases, commuter rail was electrified decades before intercity mainlines: for example, Japan started electrifying Tokyo’s innermost commuter lines in the 1900s and completed them in the 1920s and early 30s, but took until 1956 to electrify the first intercity line, the Tokaido Line.
However, in some dense regions, even the intercity lines have many stops. Cities in Israel, Belgium, the Netherlands, and Switzerland are just not very far apart, which blurs the distinction between regional and intercity lines somewhat. Switzerland is all-electrified, and my post from 2015 argued that the first three should be, too. In the US, there are specific regions where continuous sprawl has led to the same blurring: the Northeast Corridor, Southern California, Central and South Florida, New England. All are characterized by high population density. New England has closely spaced cities, whereas the LA-San Diego corridor and corridors within Florida have so much sprawl that there have to be several stations per metro area to collect people, reducing stop spacing.
Frequent sharp curves between long straight segments
Electric multiple units (EMUs) can make use of their high acceleration not at stations, but also at slow restrictions due to curves. They are also capable of higher cant deficiency than top-heavy diesel locomotives, since they have low center of gravity, but the difference for non-tilting trains is not so big. A uniformly curvy line does not offer EMUs much advantage, since all trains are slow – if anything, the lower the top speed, the less relevant acceleration is.
The big opportunity to accelerate is then when a mostly straight line is punctured by short, sharp curves. Slowing briefly from 130 km/h to 70 km/h and then speeding back up costs a FLIRT on the order of 15 seconds. A diesel train, whether powered by a locomotive or by diesel multiple units (DMUs), can’t hope to have the required power-to-weight ratio for such performance.
EMUs’ better acceleration profile makes them better-suited for climbing hills and mountains. Modern EMUs, especially low- and medium-speed ones optimized for high acceleration, can effortlessly climb 4% grades, at which point DMUs strain and diesel locomotives require helper engines. When the terrain is so mountainous that tunnels are unavoidable, electric trains do not require ventilation in their tunnels. As a result, some long rail tunnels were electrified from the start. The combination of uphill climbs and tunnels is literally toxic with diesels.
Cheap, clean electricity
Electrification has lower operating costs and lower greenhouse gas emissions in areas where the electricity is powered by cheap hydro or geothermal power than in areas where it is powered by fossil fuels. Switzerland became the only country with 100% rail electrification because it had extensive hydro power in the middle of the 20th century and was worried about relying on coal shipments from Nazi Germany during the war.
This is especially useful in far northern countries, like Sweden and Canada, which have low population density and little evaporation, leading to extensive hydro potential per capita. Despite its low density, Sweden has electrified about two thirds of its rail network. In the US, this is the most relevant to the Pacific Northwest.
But in the future, the falling cost of solar power means that clean electricity is becoming more affordable, fast. This favors electrification in more places, starting from sunny regions like most of the US.
Small installed diesel base
A rich or middle-income country building railroads for the first time, or expanding a small system, needs to build new yards, train maintenance crews, and procure spare parts. It should consider electrifying from the start in order to leapfrog diesel technology, in the same manner many developing countries today leapfrog obsolete technologies like landline phones. In contrast, a larger installed base means electrification has to clear a higher bar to be successful, which is why Japan, France, and other major core networks do not fully electrify.
The US situation is dicey in that it does have a lot of diesel equipment. However, this equipment is substandard: reliability is low, with mean distance between failures (MDBF) of about 45,000 km on the LIRR compared with 680,000 on new EMUs (source, pp. 30-31); the trains are very heavy, due to past FRA regulations; and the equipment is almost universally diesel locomotives rather than DMUs, which makes the acceleration problem even worse than it is for GTWs. Total acceleration and deceleration penalty on American diesel locomotives is not 80 seconds but 2-2.5 minutes.
Because North America underrates electrification, some people who self-identify as forward-thinking propose DMUs. Those require new maintenance regimes and facilities, creating an entire installed base from scratch instead of moving forward to EMUs.
Globally, the installed diesel base for high-performance lines is vanishingly small. The technology exists to run diesel trains at more than 200 km/h, but it’s limited in scope and the market for it is thin.
Through-service to electric lines
Whenever a diesel line is planned to run through to an electric line, it should be a prime candidate for electrification. Dual-mode locomotives exist, but are heavy and expensive; dual-mode multiple units are lighter, but are still boutique products.
This is especially true for the two biggest investments a network can make in passenger rail: RER tunnels, and HSR. RER tunnels involve expensive urban tunneling. When a kilometer of urban subway costs $250 million and a kilometer of catenary costs $2 million, the economics of the latter become stronger. Not to mention that RERs are typically short-hop commuter rail, with frequent stops even on the branches. HSR is a different beast, since it’s intercity, but the equipment is entirely electric. Running through to a diesel branch means towing the train behind a diesel locomotive, which means the expensive HSR traction equipment is idle for long periods of time while towed; this is at best an interim solution while the connecting legacy line is wired, as in the line to Sables d’Olonne.
Nearly complete electrification
Areas where the rail network is almost completely electrified benefit from finishing the job, even if individually the diesel lines are marginal candidates for electrification. This is because in such areas, there is a very large installed electric base, and a smaller diesel base. In small countries the remaining diesel base is small, and there are efficiencies to be had from getting rid of it entirely. This is why the Netherlands and Belgium should finish electrification, and so should Denmark and Israel, which are electrifying their main lines.
This is somewhat less applicable to larger countries, such as Sweden, Poland, and especially Japan. However, India is aggressively electrifying its rail network and planning even more. Note that since networks electrify their highest-trafficked lines first, the traffic can be almost completely electrified even if the trackage is not. For example, Russia is about 50% electrified, but 86% of freight tonnage is carried on electric trains, and the share of ton-km is likely higher since the Trans-Siberian Railway is electrified.
This also applies to networks smaller than an entire country. Commuter rail systems that are mostly electrified, such as the LIRR, should complete electrification for the same reason that mostly electrified countries should. In New England and Southern California, regional rail electrification is desirable purely because of the acceleration potential, and this also makes full electrification desirable, on the principle that a large majority of those two regions’ networks have enough potential traffic to justifying being wired without considering network effects.
Every place – a country, an isolated state or province, a commuter rail system – that is at least 50-60% electrified should consider fully electrifying. The majority of the world that is below that threshold should still wire the most important lines, especially regional lines. Capital-centric countries like Britain and France often get this wrong and focus on the intercity lines serving the capital, but there are low-hanging fruit in the provincial cities. For example, the commuter rail networks in Marseille, Lyon, and Bordeaux are almost entirely electrified, but have a few diesel lines; those should be wired.
In North America, electrification is especially underrated. Entire commuter rail networks – the MBTA, Metra, Metrolink, MARC/VRE, GO Transit, AMT, tails on the New York systems – need to be wired. This is also true of short-range intercity lines, including LA-San Diego, Chicago-Milwaukee, Boston-Portland, Toronto-Niagara Falls, and future New York-Scranton. It is important that good transit activists in those regions push back and support rail electrification, explaining its extensive benefits in terms of reliability and performance and its low installation cost.