I am trying to buy a train ticket for a journey between East Croydon and Overton today. This is a simple journey, changing at Clapham Junction and Basingstoke. However, it ended up to be a hunt between different websites because the ticket didn’t show up on my preferred split ticket retailer. The itinerary was shown but it forced me to buy 3 tickets, one for each leg, to complete the journey.

I then checked the website of the train operator, South Western Railway, who sets the fare and also runs the train, and it is even worse. It refused to show me any services at all.

However, if I changed the date to two weeks later, it would show me services and tickets.

The difference between the two weeks is that, the train is diverted around an engineering work between Clapham Junction and Woking. The calling pattern is not affected and the fact that the train is diverted off the mainline is only officially announced through the engineering works poster by South Western Railway, and if I attempt to buy a ticket or check train times from Clapham Junction to Basingstoke on SWR website, there is completely NOTHING telling me that the train will run off the mainline to get around an engineering work!

Engineering work is taking place between New Malden and Surbiton, closing all lines.

Buses will replace trains between New Malden and Surbiton.

Trains that usually run via Surbiton will run to a reduced and amended timetable, with some trains running earlier or later than usual in order to be diverted around the Surbiton area.

Check before you travel:

You can plan your journey using the National Rail Enquiries Journey Planner

Replacement bus travel advice:

For helpful advice if you need to travel on a rail replacement service, including accessibility and bicycle information, please use our Rail Replacement Services page.

You can find the pick-up and set-down location of rail replacement services by checking station signage or by searching for your station on our Find a Station page.

Please be advised that replacement vehicles may be busier than usual, and you should allow extra time for your journey.

If I am on a train which suddenly runs off the expected route, I will freak out. When I lived on Bournemouth, I used this route frequently and suddenly, on an evening, after I boarded the train at Clapham Junction, it ran slowly for a long time, then I checked the GPS signal on my phone and it was running on the line to Reading! I approached the guard immediately and he told me that the train was diverted and would eventually return to Woking. It was the standard, exact diversion I am facing right now, when the line through Wimbledon or Surbiton is closed.

The only reason I know that the train is going to be diverted for today’s journey is because I am using a journey planner (Aubin) which shows the diversion on the map.

And only a minority of journey planners can show this diversion correctly. Not even Google Maps can show it right, with the line still drawn over the mainline. The same is shown in Citymapper as well (as Basingstoke is outside the coverage of Citymapper, I tried searching to Woking, and the line is also shown over the mainline)

The above screenshots are from general-purpose multi-modal public transport navigation software. If I instead look into train ticket retailers, only a minority of them actually have a map when I search for itineraries, and even fewer can show the actual train route correctly. For example, Thameslink website shows a map with the itinerary, but it only connects the calling points (not other timing points where the train do not stop) by straight lines, so it doesn’t show me that the train is diverted. As Thameslink fails to sell me the through ticket I want, I am using a search from Clapham Junction to Basingstoke to illustrate the point:

Trainline is the only retailer I have found which can correctly show me the train is diverted if I search from Clapham Junction to Overton. However, if I search from East Croydon to Overton instead, it fails to produce me any itineraries which travel on an diverted train, and forces me onto the much slower replacement buses with 5 changes! (Clapham Junction, New Malden, bus to Surbiton, Woking and Basingstoke)

Going back to the ticket itself. I have tried many train operators and the majority of them failed to produce me any results on the most straightforward route, including SWR, Thameslink, LNER. If I enter the journey onto National Rail website, the times show but it forces me to use multiple tickets. However, the ticket can be sold from c2c instead.

Among third party retailers, Trip.com (alongside with TrainPal) is the rare one which can find a split beating the above fare, by splitting at Basingstoke only, bringing the total fare down to £19.35, and it ended up getting my custom. TrainSplit forced two splits (East Croydon and Basingstoke) on my itinerary which would be more expensive, Trainline couldn’t found the above itinerary and forced me onto a replacement bus, and Uber Travel simply showed “no routes found” after I entered the journey.

Of course, if I just buy the £20 ticket from the ticket machine, no staff is going to question the validity even when the train is diverted off the mainline – it is an unwritten rule that a ticket valid on the normal route is also automatically valid on a diverted train, alongside with a ticket valid on the diverted route, but digital journey planners are not set up to handle it automatically, instead they are normally handled by train operators manually entering easements into the routing data. In this case, it is apparent that an easement is not added into the data, and the difference in interpretation in certain complicated rules in the Routeing Guide (which defines the routes I can use on a ticket) results in the ticket being sold by some retailers but not the others.

Technical details

The route is not a direct train or the shortest route, so I have to reply on the mapped routes in the Routeing Guide. The diversionary route is not directly listed as a mapped route between East Croydon and Basingstoke (the Routeing Point for Overton), but LONDON is listed as one of the options. By recursively resolving it, I can find a map combination which covers the route I am using (LB to London, WX+BU from London), but it involves changing from a London-bound map to a country-bound map short of London, at Clapham Junction.

The Routeing Guide contains the following paragraph:

If there is a route “LONDON” as one of the permitted routes in the Routeing Guide, the range of permitted routes via London is discovered by the following method:

1. Look up the permitted routes from the origin routeing point to London.
2. Look up the permitted routes from London to the destination routeing point.
3. Work out the range of permitted routes for the whole journey by combining any route found in (1) with any route found in (2). All possible combinations are permitted routes for the journey except those with a repeated map.

But it also contains the following paragraph:

Routes created from the route LONDON in the yellow pages do not oblige you to change in London. For example Oakham to Brighton has the route LONDON which yields LB+MM. This allows the journey Oakham – Leicester – Bedford – Brighton, changing at Bedford and continuing via Thameslink to Brighton.

So I believe there is ambiguity in the interpretation here, if the intention of the second paragraph allows a map combination resolved via LONDON can be used on a route which completely avoids London, changing at another station where they touch, and this scenario comes up so rarely that it may not be well tested.

South Western Railway is both the fare setter of this fare and the operator of diverted train. It falls short of my expectation of a smooth journey planning and ticketing experience in the era of digital journey planners with the above experience, where the usual ticket can only be bought from another train operator whose territory is nowhere near my journey. My impression is that it is still in the mentality of early 2000s, two decades ago, when most tickets were bought from ticket machines for walk-up travel, failing to catch up the modern online workflow, leading to its decline in the post-COVID leisure world.