
Commuters won't need telling that there's a multitude of ways train services can go awry. A broken signal. Wet leaves on train tracks. A man up a lamppost at a station (seriously). However, part of the Overground network faces a much more basic issue; it's running out of trains.
An unloved train line
The Gospel Oak to Barking Line — affectionately known as the GOBLIN — is something of an ugly stepsister to other parts of the Overground network. The majority of its stations are in zone 3, differentiating it from the more straightforward commuter-centric London lines (Watford to Euston and the Liverpool Street branches), and the London Orbital (including the East, North and South London lines, most of which run in zone 2). All these other lines operate with four- or five-carriage trains. However, the GOBLIN runs with old-school two-carriage trains.
TfL decided the time had come to show the GOBLIN some love and upgrade these diesel-chugging old Class 172s. So the route would be upgraded, a project which involved electrifying the line, and capacity would be increased by introducing four-car trains, for which some of the existing platforms needed extending. A new set of Class 710s would bring the GOBLIN into the 21st Century.
Then everything went tits up.
Station upgrade problems
Only a small part of the line around South Tottenham was previously electrified, so the entire line needed work before the new trains arrived, which meant the closure of the line and the introduction of the dreaded replacement rail bus service. This lasted... a while.
London doesn't have a particularly good track record at delivering massive infrastructure projects on time, but disasters aren't usually this basic in their genesis. The overhead wires necessary for electrification were 'incorrectly designed'. Yes, you read that right. Someone made an enormous cock-up at the design stage and no-one noticed until they started construction. This set things back a few months, which meant more replacement rail bus journeys for beleaguered commuters.

The trains that are over a year late
As annoying as those problems were, they're all in the past. Somehow Network Rail managed to electrify the line in time for January 2018 — the date the new Class 710s were due to be ready. However, at time of writing, not a single Class 710 has been delivered by Bombardier, the engineering firm building the trains. And in case you've lost your calendar and have no idea what the current date is, that makes these trains over a year late.
London Overground Class 710 at London Liverpool Street. pic.twitter.com/XqGbkGUG3w
— Julian G (@julog90) December 6, 2018
Apparently it's software on board that's at the heart of the hold up. It's not working reliably, a serious issue considering it manages many of the critical safety systems. When's this all going to be sorted out? No idea. There's no end date in sight. Some have been spotted in testing, but no one's willing to even conjecture when the new fleet will be up and running.
Goodbye diesel
'So what if the new trains are late?', we hear you cry. 'Just keep using the old ones. They might be packed like sardine cans, and pumping out fumes that clog up London's air, but any trains are better than no trains.'
TfL would most likely love to keep running the old trains until the new ones are delivered — but it can't. The lease on the old carriages expired in June 2018. By the time it became clear that the new trains weren't going to make it on time, it was too late to extend the lease, as they've been sold off to West Midlands Trains.
Some have already gone to the Midlands, leaving just a few for the rest of the line... until further trains were drafted in to come to the rescue. No, not the new trains that were ordered and should already be here —instead, trains from other parts of the Overground network had to be drafted in.
378 206 Gospel Oak earlier today (22/2/19) #DailyPick #Goblin @RidingtheGoblin pic.twitter.com/1jCxkDYLol
— Simon (@citytransportin) February 22, 2019
TfL decided the best thing to do was to spread its problems around. It's nicked three Class 378s from the orbital routes to run on the GOBLIN. One of the upshots of the electrification finally being completed is that these trains only needed minor modifications — like losing a carriage — to run on the line.
We've noticed that the moquette on these refurbished trains has gone a bit green. This is the new moquette that's due on the Class 710s when they finally arrive. That's like giving a kid a t-shirt for an Action Man rather than an actual Action Man for Christmas. Not ok, TfL.

What next?
By the middle of March 2019 all eight of the original trains will have said their farewells. Now you don't have to be a maths boffin to realise that for a line that needs eight trains to function normally, only having three is a total disaster. At best the service will run at half capacity — i.e. a train every half hour. At worst? Expect to see a lot more rail replacement bus services over the coming months.
There is a modicum of good news for GOBLIN users. When the new 710s do eventually arrive, everyone is going to get a month's worth of free travel on them. Barking here we come (at a currently undecided point in the future)!
With thanks to the Barking-Gospel Oak Rail User Group. Its website is a great place to keep up with this nightmare saga.