Written by Laggingcomputer, Published 2023/12/04
Although I'd be surprised if anybody stumbled upon my article without prior knowledge about what Seoul's GTX project is, it would be very rude of me to assume that everybody reading this article would have that knowledge.
Basically, GTX, or Great Train eXpress, is a regional express metro, akin to Paris' RER, London's Crossrail, or various Chinse Express Metros; it will make stops in major hubs within Seoul, and major feeder hubs in suburban parts of greater Seoul. The three lines, named GTX-A, GTX-B, and GTX-C, all have slightly different characteristics, but they all fit into this general description. These lines are slated to have an operating speed of 180 km/h, with 3 doors per car, all level boarding.
GTX-A is by far the quickest in its progress, set to open its first few phases in 2024, with the following phases coming as late as 2028. GTX-A will share existing high-speed tracks from Suseo to Dongtan, and have brand-new dedicated tracks from Suseo all the way to its northwestern end.
GTX-B is by far the slowest, as it had the lowest B/C (benefit over cost) value in the initial planning stages. It is now planned to be a weird hybrid project. The Yongsan - Sangbong section, planned to be the first part to start construction, will be an underground mainline, with mainline trains (including KTX) trains using it to come into the city from the east. The Sangbong - Chuncheon section will use existing tracks of Gyeongchun line, requiring minimal station modifications. The section from Yongsan to the southwest terminus will be on brand-new dedicated tracks. The line is slated to start operations early next decade.
GTX-C is actually being progressed decently fast, being planned to open in 2028. It will share existing tracks of the lines 1 and 4 in the south, and line 1 in the north. Only the core, from Yangjae to Cheongnyangni, will be brand-new dedicated tracks.
As I mentioned earlier, GTX-B is expected to have KTX trains and other mainline trains, but this is completely expected. After all, a deep-level mainline that connects Seoul Station to Cheongnyangni had been floating around the railfanning community for a while, proposed as a way to relieve capacity constrains on the mainline tracks into Seoul from the east, serving trains to Chuncheon, Gangneung, Donghae, Andong, and many more cities. There is nothing wrong with a project like this. This was factored into the planning pretty early into the project, and these two projects -- the new deep-level mainline and GTX -- compliment each other very well when combined like this.
A more controversial proposal, however, is that GTX-C and GTX-A core sections, which are supposed to be completely dedicated tracks, may get some mainline trains through them, after all.
Uijeongbu city, north of Seoul, has officially requested that mainline high-speed trains be run to Uijeongbu station using GTX-C and GTX-A tracks from Suseo. The theory goes that -- since all GTX lines will be using 25kV 60hz AC and standard gauge, same as mainlines -- it should be possible to run KTX or SRT trains from Uijeongbu, run them through GTX-C to Samseong, then run them through GTX-A to Suseo to meet with existing SRT tracks.
This will require no additional infrastructure save for some funky PSDs (platform screen doors) at Samseong station and GTX platforms at Suseo stations. GTX-A will already have track connections to be able to share tracks with SRT, and GTX-C will have track connections to be able to share tracks with Line 1, with Samseong station always having been planned to get some crossover switches between GTX lines. The platform height is also no problem, since EMU-320, a proper high-speed version of KTX-Eum (compatible with both high and low platforms) is already doing test runs.
This means that this is a very low-cost project, requiring minor PSD modifications only, that will bring HSR service to a major satellite city of Seoul, not to mention to a major station in downtown Gangnam, much more accessible than current HSR termini of Suseo or Seoul.
I know some people in the readers, especially those from Europe or North America, probably had a bit of an internal scream as they read the previous section. A regional metro that was supposed to have some dedicated track sections, now getting some other trains on its tracks. Surely, this can't be good, right? This is surely a sign of infrastructure creep and GTX will be doomed!
Well, not really. Frankly, GTX-C already got a bunch of infrastructure creep due to budget concerns. It was never supposed to share tracks with line 4, as the section of line 4 that it now seeks to share tracks with, the Gwacheon line, is a rather archaic line from '90s that was built more like a metro than a mainline. On the Gyeongbu line (the southern section it shares with line 1), it will take the slower, line 1 tracks rather than mainline tracks used by ITX and freight trains, and the Gyeongwon line (the northern part it shares with line 1) is more of a metro line than a mainline at this point anyways. These factors already constrain GTX-C's frequency by a considerable amount, to a point that a few high-speed trains can't hurt the frequency too much.
As for GTX-A, it was always expected to share tracks with SRT; in fact, that was one of the many considerations they factored in for B/C calculations of the Suseo-Pyeongtaek HSR. If it already shares tracks with SRT in the south, it really won't hurt to have just some of those HSR trains come into GTX-A proper after all. What's more, Samseong-Suseo will be just one stop on the GTX-A anyways, so it will be a relatively short extension of the shared-track section that brings a lot of benefits.
I would say this should be expanded to more such projects across the world. Of course, not every project is fit for this, as there may be compatibility issues or other constrains that make such non-dedication of tracks not feasible. But I would like to remind you, my dear reader, that a Liverpool to Heathrow Airport service through Crossrail 1, stopping at several major stations in London, is theoretically feasible, if a bit impractical. Crossrail 2 could serve as an alternative route for West Anglia Main Line to come into London. It could serve as an alternate line to use when the lines into Liverpool Street are simply disrupted, or as regular service to increase frequency into London. I know that my knowledge of European rail lines is limited, so I can't really say much about them, but it might be worth looking into sacrificing some frequency to achieve an increased level of convenience.