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At Fukushima Station in Fukushima Prefecture, construction is underway to add an approach track for Yamagata Shinkansen trains. We will explain the details and significance of this construction work with photos of the site.
What are the approach lines to Fukushima Station?
The Yamagata Shinkansen, also known as the Tsubasa , began operation in 1992. Currently, it mainly operates between Tokyo Station and Yamagata Station and Shinjo Station in Yamagata Prefecture.
The Tsubasa runs on the Tohoku Shinkansen tracks between Tokyo Station and Fukushima Station. Many Tsubasa trains also run coupled with the Yamabiko The Yamabiko mainly runs between Tokyo Station and Sendai Station or Morioka Station.
The Yamabiko (left) and Tsubasa (right) trains running coupled from Tokyo Station to Fukushima Station (Photo by author: All images below, except for Google Maps, were also taken or created by the author)
After detaching from Fukushima Station, the Yamabiko will enter the Ou Main Line and head to Yamagata Station or Shinjo Station. The " Yamagata Shinkansen " is the collective name for the Tohoku Shinkansen between Tokyo Station and Fukushima Station, and the Ou Main Line between Fukushima Station and Yamagata Station or Shinjo Station, and is also the nickname for the train (Tsubasa) that runs on this section.
Please see this article for details on how the Yamagata Shinkansen was born
As already explained, Tsubasa trains heading down to Yamagata and Shinjo stop at Fukushima Station on the Tohoku Shinkansen before transferring from the Tohoku Shinkansen to the Ou Main Line. For Tsubasa trains heading up to Tokyo, the process is of course reversed, transferring from the Ou Main Line to Fukushima Station on the Tohoku Shinkansen. Trains that are coupled with Yamabiko are coupled at Fukushima Station. The track that Tsubasa uses to travel between the Tohoku Shinkansen and the Ou Main Line is the "approach line.
What is the problem with the current approach?
Here is a simple diagram showing the current wiring at Fukushima Station on the Tohoku Shinkansen
Fukushima Station wiring diagram (arrows in the diagram indicate the direction trains can travel)
Platform 11 is an up-track platform, and is designed to allow trains to enter from the Sendai direction, but it is currently not in use
Platform 12 is for upbound trains, and Yamabiko trains that do not connect with Tsubasa at Fukushima Station will stop here
The two tracks between platforms 12 and 13 are for passing trains. The Tohoku Shinkansen Hayabusa and the Akita Shinkansen Komachi do not stop at Fukushima Station, so they run through these tracks at high speeds.
Platform 13 is for outbound trains, and is also where the Yamabiko, which does not connect with the Tsubasa, stops
And then there's platform 14. I'll explain the details later, but the "Tsubasa" and the "Yamabiko" which runs in conjunction with the "Tsubasa" must stop on this platform, both inbound and outbound trains .
First, the outbound Yamabiko and Tsubasa trains will stop at platform 14 and be uncoupled, allowing the Tsubasa to depart first, passing through the current approach line and descending to the Ou Main Line tracks, heading towards Yamagata
Afterwards, the Yamabiko departs for Sendai
The problem is the train heading up to Tokyo
First, the Yamabiko enters platform 14, crossing over from the up line to the down line
After that, the Tsubasa travels up the approach track from the Ou Main Line, enters platform 14, and connects with the Yamabiko. the approach track only connects to platform 14 , the Tsubasa can only enter platform 14, which is why the Yamabiko also has to go out of its way to enter platform 14 to wait for the Tsubasa. Note that the Yamabiko, which is not connected to the Tsubasa, does not need to enter platform 14, so it stops at platform 12.
After the Yamabiko and Tsubasa are coupled, the train crosses the down track again onto the up track and heads towards Tokyo. Note that in the diagram above, Tsubasa is coupled to Yamabiko, but some Tsubasa trains do not couple with Yamabiko. However , as mentioned earlier, Tsubasa can only enter platform 14. Therefore, when an upbound Tsubasa departs Fukushima Station, it will cross the down track as long as the upbound Tsubasa is running (whether it is coupled with Yamabiko or not) .
The train crosses the down line once when the upbound "Tsubasa" is running alone, and twice when the "Tsubasa" and "Yamabiko" are running in conjunction. Naturally, while the upbound train is crossing the down line, the downbound train cannot pass through Fukushima Station. Therefore , the single issue of Fukushima Station places significant constraints on the timetable for the Tohoku and Yamagata Shinkansen.
Furthermore, if the timetable is disrupted, situations will arise whereby passing down trains will have to wait for up trains to cross the down line (it is said that when a high-speed Shinkansen train stops, the journey time will increase by five minutes), or conversely, up trains such as Yamabiko and Tsubasa will have to wait for down trains to pass, or down and up Tsubasa trains will compete for platform 14, further exacerbating the disruption to the timetable
If the schedule is significantly disrupted, the impact will not be limited to the Tohoku Shinkansen or Yamagata Shinkansen. The Joetsu Shinkansen and Hokuriku Shinkansen also run on the Tohoku Shinkansen tracks between Tokyo Station and Omiya Station. This means that if the schedules of the Tohoku Shinkansen or Yamagata Shinkansen are disrupted, the disruption will be amplified at Fukushima Station, potentially disrupting the schedules of Shinkansen trains bound for Niigata, Kanazawa, and Tsuruga
There is also another problem. As explained above, the Yamabiko bound for Tokyo stops at platform 12 when it is not coupled with the Tsubasa, and at platform 14 when it is coupled with the Tsubasa. If you want to take the Yamabiko bound for Tokyo from Fukushima Station, the platform you should go to will differ depending on the train. No one will disagree that this is confusing (although for those who often use large stations such as Tokyo Station or Shin-Osaka Station, this may seem obvious...).
Details of the approach line expansion work
Currently, the bottleneck at Fukushima Station is that the Yamabiko and Tsubasa trains going up the line have to cross the outbound line twice. The reason they have to cross twice is because the current approach track only connects to platform 14 at Fukushima Station. It's easy to come up with a way to solve this problem.
New approach line for the ascending Tsubasa train
As shown in the diagram above, the current approach line should be reserved for the outbound Tsubasa trains, and should be constructed to connect to the inbound platform at Fukushima Station for the inbound Tsubasa trains
With this layout, the Yamabiko bound for Tokyo will stop at platform 11 on the Tokyo side first to wait for the Tsubasa, and the Tsubasa will then travel along the new approach track from the Ou Main Line to platform 11 at Fukushima Station, where it can couple with the Yamabiko. This means that Yamabiko will no longer need to cross the down track when entering Fukushima Station .
When the Yamabiko and Tsubasa depart Fukushima Station, they do not cross over the outbound tracks. Because inbound trains will no longer cross the outbound tracks, the flexibility of timetables will be greatly improved and the occurrence of timetable disruptions at Fukushima Station will be reduced.
Also, because there is only one existing approach line, it was not possible for the outbound Tsubasa trains to depart and the inbound Tsubasa trains to arrive at Fukushima Station at the same time, but this will now be possible. Once the new approach line is completed, the previous constraints will be removed, which may lead to an increase in the number of Tsubasa trains.
The platform number for the Yamabiko trains heading up the line will be platform 11 for trains that will be coupled with the Tsubasa, and platform 12 for trains that will not. This will also eliminate the hassle of having to check the platform where the Yamabiko will be stopping before going up to the platform.
The localized construction work at Fukushima Station, which involves adding an approach track, .
The new approach line took time to realize
The need for an approach line dedicated to the upbound Tsubasa trains seems to have been recognized within JR East, the company that operates the Shinkansen, at the latest around 2005. However, it was easy to imagine that construction of a new approach line would be difficult, and it took a long time to realize because it required time for consideration and waiting for advances in construction technology.
As shown in the diagram I created, the new approach line must pass under the Tohoku Shinkansen, then make a sharp curve to reach the elevated platform at Fukushima Station . And, although not shown in the diagram, it must take a route that avoids interfering with the conventional lines running above ground. Furthermore, on the north side of the station (the right side of the diagram), there is a road bridge over the conventional line, the Nishimachi Overbridge on Fukushima Prefectural Route 310, Niwasaka Fukushima Line. The new approach line must cross the Niwasaka Kaido Overbridge at a height that allows ample space to avoid obstructing vehicles passing over it.
As a result, the new approach line is not only curved, has a steep uphill slope The gradient is 33‰ (per mille), meaning that for every kilometer traveled horizontally, the slope rises 33m (an angle whose tangent is 0.033), which translates to an angle of 1.89 degrees. While this may be acceptable for automobiles, it is quite steep for a train. However, even before arriving at Fukushima Station, the ascending Tsubasa train crosses Itaya Pass, which has an average gradient of 33‰, between Yonezawa Station and Fukushima Station, so even if another 33‰ uphill slope is added, it should not be impossible to climb.
For more information about the Itaya Pass railway, please see this article
With its sharp curves and steep gradients, the new approach line resembles a junction on an urban expressway. It's best to see it for yourself, so from here on I'll provide an explanation with photos.
Current status of approach line expansion work
Below, I will introduce the current status of the approach line expansion construction, based on photos I took on site in early August 2024. Please note that the photos were taken from public roads, sidewalks, platforms, etc. No photos were taken in areas where public access is restricted.
The new approach line, which branches off from the Ou Main Line's up line, begins to gain altitude towards Fukushima Station after passing Mikawa level crossing near Fukushima Station (currently only local trains on the Ou Main Line pass through Mikawa level crossing, but once the new approach line begins operation, up-bound Tsubasa trains will also pass through).
The Mikawa crossing is at the center of this aerial photograph. The new approach line extending southeast to Fukushima Station is already visible as of September 2024, when this article was written.
The tracks for the new approach line have already been laid, but the overhead lines that supply electricity to the trains have not yet been installed. Construction of the electrical equipment will likely begin soon. The viaduct that runs above the new approach line is the track of the Tohoku Shinkansen.
This elevated line is the current approach line
The current approach line slopes gently downwards towards Yamagata
The new approach line steadily gains altitude and passes under the Tohoku Shinkansen viaduct
The train comes closest to the Tohoku Main Line at Soneda (East) crossing, which is a crossing for the Tohoku Main Line, Fukushima Transportation Iizaka Line, and Abukuma Express Line. From here, it curves further and approaches the Tohoku Shinkansen tracks that it once passed under. The small cream-colored bridge visible in the background is the section that crosses over the Niwazaka Fukushima Line Nishimachi Overbridge.
As you can imagine from the name Soneda (East) Crossing, Soneda Station on the Iizaka Line is located right after crossing this crossing
Photographed from the Nishimachi Overpass Bridge, crossing the bridge
And then head to Fukushima Station..
This is the section that connects to the Tohoku Shinkansen tracks (the new approach line is the track on the far right). At present, a wire mesh gate has been installed.
The tracks continue to platform 11, which is currently a spare platform
At this time (early August), the Yamagata Shinkansen was partially suspended due to the effects of the heavy rain disaster in late July, and the Tsubasa train that was supposed to be bound for Shinjo had a sign indicating an unusual destination: "To Oishida."
Furthermore, on the day I was scheduled to board the Shinkansen from Fukushima Station, a signaling problem on the Ou Main Line caused significant delays to the Yamagata Shinkansen, which in turn affected the Tohoku Shinkansen, causing confusion. This was a firsthand experience of the need for a new approach track.
summary
Construction of the viaduct and tracks on the new approach line is already well underway, and it looks as though trains will soon be able to run on it, but work on the electrical equipment and other aspects is still to come, and careful test runs will be necessary even after completion. It has been announced that the new approach line is scheduled to begin operation at the end of fiscal year 2026. It is likely that upbound "Tsubasa" commercial trains will begin running on this new track from the day the JR Group's timetable is revised in March 2027. This track, just a few hundred meters long, will greatly enhance the convenience and operational reliability of East Japan's Shinkansen in the future.
![3106705_l](https://jp.neft.asia/wp-content/uploads/2024/05/3106705_l-150x150.jpg.webp "Why was the Yamagata Shinkansen "Tsubasa" mini-shinkansen created? [Yamagata Prefecture]")
![cb115f1bbd09cb04b9138b7ecd35f6c6.jpg](https://jp.neft.asia/wp-content/uploads/2023/06/cb115f1bbd09cb04b9138b7ecd35f6c6.jpg-150x150.webp "Yamagata Prefecture's "Sokushinbutsu" and Yudonosan's "Reincarnation Belief"")
