Shoulder stations
Rapid transit lines shouldn’t only interchange in the centre. You should be able to change trains in the suburbs as well.
Of the ten busiest railway stations in Great Britain, all of them are in London. But one of them is not like the others. The fifth busiest, Stratford, with 101 million passengers per year,1 is 9 km away from Charing Cross. It is the only one of the top ten not in central London.
Why would a station so far from the centre be so busy? The answer is simple: it is one of the best-connected places in London. Across its seventeen platforms, Stratford station has the Elizabeth Line; the Central and Jubilee Lines; two branches of the DLR; a branch of the Overground; and Greater Anglia services to Essex, Norfolk, Suffolk and some of London’s suburbs.
This gives it enormous value as an interchange station: journeys like Colchester to the West End, or Hackney to the O2 Arena in North Greenwich, all involve changing trains at Stratford, rather than going into central London and out again.
It also means the area has become a destination in its own right, because it is so accessible. This is the reason the 2012 Olympics were hosted in Stratford: it offered a huge area of brownfield land which was remarkably easy to get to.
Stratford is what is known as a shoulder station, an interchange node that is outside the city centre, and at which all or nearly all trains stop. The term shoulder station is a double entendre: they allow passengers to change trains on the ‘shoulders’ of the city centre. In doing so, they relieve pressure on central interchange stations: in other words, they ‘shoulder’ the burden of passengers.
Shoulder stations are a good idea, and should be part of the conceptual vocabulary of anybody who cares about good public transport. Like many good transit ideas, the concept is fairly self-explanatory, they are very common around the world, and they are almost entirely absent in Britain, outside a few examples in London.
Edit: I believe the term ‘shoulder station’ was coined by Reece Martin, aka RMTransit on YouTube. Apologies for not realising this and crediting him sooner.
Network design and shoulder stations
Here is a diagram of a simple rapid transit network in a medium-sized city. It has a network of suburban trains shown in green, and three metro lines shown in red, blue and black. The city centre is shown with the shading, and the doughnut symbol is an interchange, as on the Tube Map.
This is, in fact, the way that Stockholm has laid out its metro. All three metro lines, and the tunnel for suburban trains, interchange at the same station complex. In one sense this is convenient – everybody is, at most, one interchange away from every other station in the network. But it also means that this central interchange station is overloaded with passengers.
This is another simple rapid transit network, using the same symbology.
This is designed to spread the interchanging passengers out more evenly. One interchange has three lines, while the others have two. This is very similar to how Hamburg, Munich and Frankfurt have laid out their networks.
Rapid transit systems are useful to passengers because they are networks. This means that every line should ideally interchange with every other line; if not, then the system is less of a network and more of a collection of individual lines.
In a medium-sized city like Munich or Manchester, this is non-negotiable. In a megacity like London, it is not always possible for every line to interchange with every other,2 but the city should still try. In particular, it should avoid gratuitous missed connections, where two lines cross without a station.3
The network immediately above achieves this. But the fact that the only interchanges are in the centre still has the potential for overloading, and it is inconvenient for passengers who are making suburb <> suburb journeys, which forces them to go into the centre and then out again.
We can solve this problem by building interchange stations in the suburbs. These are shoulder stations.
This is similar to how Munich’s network works. This layout means the central interchange stations become less crowded.
Shoulder stations can also speed up some journeys: on the diagram above, if you’re travelling from the northern reaches of the blue line to the central area served by the black line, it’s obvious that the shoulder station makes the journey faster.
Shoulder stations also make suburb <> suburb journeys easier. This needs to be taken with a pinch of salt as a justification: there are not very many suburb <> suburb journeys, and they tend to be occasional travel rather than regular commutes, so produce fewer wider economic benefits. Orbital buses are usually the right solution. But sometimes it is worth making specific provision for journeys that do not touch the centre, if a city has a major out-of-centre destination, like an airport or an exhibition centre or a big office park.
Shoulder stations in Britain
Like many good train ideas, Britain discovered shoulder stations a long time ago, but, notwithstanding exceptions like Stratford, has never properly implemented the concept.
British Rail was keen on shoulder stations on intercity services: to this day, very nearly all long-distance trains stop at Stockport, Chesterfield, Wakefield Westgate and Birmingham International. But because, respectively, Manchester, Sheffield, West Yorkshire and Birmingham do not have rapid transit systems to speak of, the value of these shoulder stations (with the possible exception of Stockport) is mainly limited to park-and-ride railheads.
They have been more successful in London: as well as Stratford, other examples are Clapham Junction, East Croydon, Wimbledon, Finsbury Park, Lewisham and in the future Old Oak Common. Outside London, the most obvious example is Partick in Glasgow, where the western suburban lines interchange with the Subway.
But we should make better use of them. For instance, Harry Rushworth has proposed terminating HS2 at an ‘Ordsall station’ in Manchester. I disagree that HS2 should terminate there – city-centre stations are extremely valuable – but the location is perfect for building a shoulder station. It is connected to nearly every line going through Manchester, and the station should be relatively easy to build, as it would be on the site of a retail park. Furthermore, the surrounding area is well-suited to being developed in the future.
Elsewhere in Greater Manchester, Stockport and Bolton are obvious shoulder stations which should be expanded. In Liverpool, Broad Green would make an excellent shoulder station if the Merseyrail Northern Line were extended to St Helens and Wigan.
It is tempting, when bemoaning the state of Britain’s railways, to say, ‘Manchester should have a metro’ or ‘Leeds should have a tram’. I do not disagree with these statements, but they are not enough in themselves. As well as demanding a particular technology, we need to think about how to design those rapid transit systems. Shoulder stations are one tool that we can use to give our cities the public transport networks they deserve.
This is the combined total for Tube+DLR, and National Rail (Elizabeth Line, Overground and Greater Anglia). A further 5.5 million passengers used it just to change trains between National Rail services. In 2019, the only year for which figures are available, there were 128 million ‘passenger movements’ which include passengers using the station but only interchanging between lines.
Consider London: how is the East London Line of the Overground (and formerly of the Underground) going to interchange with the Charing Cross Branch of the Northern Line in the centre? The two lines run in parallel to one another and go to very different places, so a central interchange would not be possible.
For instance, the Northern Line Extension to Battersea crosses the Victoria Line between Vauxhall and Stockwell, but there is no station. The NLE should have been routed via Vauxhall for the interchange benefits. I don’t have much time for arguments that this would make the Victoria Line even more overcrowded: crowding shows that a railway network is doing its job well, and the answer to crowding is to increase fares, not to make new infrastructure less useful to passengers.
Bristol Parkway would become one/ even more of one if some form of metro/tram ever gets built.