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which straddles the border between Fukushima and Yamagata prefecturesThe Itaya Pass, is traversed by JR East's Yamagata Shinkansen and Yamagata Line, officially known as the Ou Main Line. As evidenced by the current operation of the Yamagata Shinkansen Tsubasa, the Ou Main Line plays an important role in connecting the Kanto region and Fukushima with various parts of the Tohoku region. However, the Itaya Pass has always been known as a difficult pass. This article introduces the railway history of the Itaya Pass.
What is Itaya Pass?
Itaya Pass is one of the mountain passes located near the border between Yamagata and Fukushima prefectures, crossing the Ou Mountains. It connects the Itaya and Osawa settlements in Yonezawa City, Yamagata Prefecture. The JR East Ou Main Line runs over this pass, so trains heading from Fukushima Station towards Yonezawa Station and Yamagata Station always pass through it. There is also a road that crosses Itaya Pass, but it is off the main route connecting Fukushima City and Yonezawa City. The main routes, National Route 13 and the Tohoku Chuo Expressway, pass through Kuriko Pass, which is further north than Itaya Pass. For this reason, the term Itaya Pass has come to be primarily associated with the railway, and is sometimes used almost synonymously with the section of the Ou Main Line between Fukushima Station and Yonezawa Station.
The gradient of Itaya Pass38‰ (3.8%) at its steepest pointis This means that for every 1,000 meters traveled horizontally, the elevation changes by 38 meters. While a 3.8% slope is not particularly steep for cars, it is a very steep gradient for railways. currentlythe steepest gradient among the "main lines classified as JR lines. Furthermore,the length of the gradient, which averages 33.0‰ and continues for approximately 22 km, also makes Itaya Pass a difficult section of the line. Being in the mountains, it is also plagued by heavy snowfall in winter.
The Yamagata Shinkansen "Tsubasa" train running near Itaya Station
Opening of the railway through Itaya Pass
The railway line between Fukushima Station and Yonezawa Station, which passed through Itaya Pass, opened in May 1899. As this was during the Meiji era, steam locomotives were used as the power source for the trains. The nearly 40 tunnels built through Itaya Pass presented a major problem for trains pulled by steam locomotives. Steam locomotives emitted large amounts of smoke, especially when climbing slopes, andthis smoke caused discomfort to train crews and passengers in the tunnels.
Steam locomotives continued to operate trains for half a century, until 1949, after the war. A documentary of the Electrification of the Ou Line" captures scenes of crew and passengers suffering from the smoke, and how, due to the infrequent train service, children attending schools at the foot of the mountains wouldwait at the station until evening before being given a special ride on a freight train to return home.
Another problem with using steam locomotives is that they are underpowered. While steam locomotives, with their plumes of smoke and loud noises, may look powerful, their actual pulling power is inferior to that of electric locomotives. This low pulling power directly translates to the problem of difficulty in climbing mountain passes.
The four stations located along the mountain pass—Akaiwa, Itaya, Toge, and Osawa—switchback stationswere For operational safety reasons, stations could not be built on steep inclines, so at these stations, flat land was secured beside the main line, and platforms were built there. Trains had to change direction to enter or exit the stations located beside the main line, which significantly affected the speed of the trains.
Furthermore, since locomotives designed to pull trains on flat lines alone cannot climb the steep gradient of the Itaya Pass, auxiliary locomotives were assigned to be coupled to trains passing through the Itaya Pass to provide assistance. In later years, these auxiliary locomotives were designed specifically for the Itaya Pass.
4110 class steam locomotive, a support locomotive for the Itaya Pass (from Wikipedia)
Serious problems such as the smoke from steam locomotives could not be ignored, so electrification work was planned at Itaya Pass early after the war, that is, the installation of equipment to supply electricity to trains so that electric locomotives could be used, and construction began in 1946
Electrification of Itaya Pass
The electrification of the Itaya Pass was extremely difficult due to the lack of major roads nearby and the heavy snowfall in the area. Three years after construction began, in 1949, train operations using 1,500V DC power started. DC electric locomotives such as the EF15, EF16, and EF64, which were developed for mountainous routes, were put into service.
EF16 electric locomotive (photo by author)
Furthermore, in the era when steam locomotives were in operation, the four switchback stations required trains that did not stop at the stations to perform the switchback maneuver. However,through tracks that allowed through trains to bypass the stationswas carried out in parallel with the electrification work, making it possible for through trains to operate smoothly.
using KiHa 80 series diesel railcarsthe limited express "Tsubasa", and from 1964,the limited express "Yamabato"(between Ueno Station and Yamagata Station) also began operation. The KiHa 80 series diesel railcars were self-propelled vehicles that ran on diesel fuel, but even these limited express trains required the coupling of an auxiliary locomotive when crossing the Itaya Pass. The KiHa 181 series, the successor to the KiHa 80 series, was initially operated without an auxiliary locomotive, but because the load on the engine at the Itaya Pass was too great, an auxiliary locomotive was coupled again. This serves as a stark reminder of just how difficult the Itaya Pass was.
Kiha 80 series diesel railcar
Approximately 20 years after the DC electrification, the lines around Itaya Pass (such as the Tohoku Main Line) were electrified with AC 50Hz/20,000V, so the electrification system for Itaya Pass was also changed to AC in 1968. New electric locomotives, the ED78 and EF71 types, which were developed for AC electrified mountain lines, were introduced. These locomotives were used to haul not only local trains but also the sleeper express "Akebono" (between Ueno Station and Aomori Station, etc.). However, the sleeper express trains, in particular, had long formations and placed a heavy load on the locomotives, so on Itaya Pass, double-heading with two ED78 or EF71 locomotives coupled together was used for hauling.
In 1975, the entire Ou Main Line was electrified. This led to a change in the operation of limited express trains such as the "Tsubasa," which crossed the Itaya Pass, to the 485 series electric trains, which were representative of the limited express electric trains of the JNR era, and the coupling of auxiliary locomotives became unnecessary.
Limited express "Tsubasa" operated by 485 series electric train
Yamagata Shinkansen opens
In the 1980s,mini-Shinkansendiscussions began on the This was a concept to run Shinkansen trains directly on conventional lines. Based on this concept, direct trains were established between the Ou Main Line and the Tohoku Shinkansen, which opened in 1982, via Fukushima Station. This is the currentYamagata Shinkansen.
Please take a look at this article which explains how the Yamagata Shinkansen came to be
The opening of the Yamagata Shinkansen was a major transformation for the Itaya Pass, similar to the electrification of the line in the 1940s. The distance between the two rails was widened from 1,067 mm to 1,435 mm, the same as the Tohoku Shinkansen, making it impossible for any trains that had previously crossed the Itaya Pass to pass. Express trains were replaced by the 400 seriesShinkansen "Tsubasa"express train that was operated with the 485 seriesTsubasa), and local trains that were previously pulled by electric locomotives were replaced by the 719 series electric trains. The 400 series was later replaced by the E3 series, and since 2024, replacement with the latest E8 series has begun.
The four switchback stations at Itaya Pass were symbolic of the pass's challenging terrain, butthe switchbackshave now been eliminated at all of them. The platforms at the four stations have been moved from sidings to the main line, transforming them into typical stations. Furthermore, Akaiwa Station, the only one of the four located in Fukushima Prefecture, was closed in 2021 due to depopulation in the surrounding area.
"Tsubasa" passing through Toge Station after the switchback is removed
As a child, I remember being taken on local trains over the Itaya Pass using 50 series passenger cars before the switchbacks were eliminated, and also on local trains and the "Tsubasa" after the Yamagata Shinkansen opened, both by my father, who was from Fukushima City. My memory of riding before the switchbacks were eliminated is vague because I was so young at the time (and my father has since passed away, so there's no way to confirm it), but I do remember the train entering the station in reverse with the red passenger cars at the front, and the train changing direction inside a tunnel (?), so I'm sure it was a local train over the Itaya Pass. These are still pleasant memories for me, albeit fragmented, but I think my father probably went on these trains because he wanted to ride them more than anything else before the switchbacks over the Itaya Pass were eliminated.
Itaya Pass is still a difficult pass
Since the opening of the Yamagata Shinkansen in 1992, the Shinkansen's "Tsubasa" and electrified local trains have been able to easily traverse the steep gradient of the Itaya Pass. However, while it is no longer a difficult section in the sense ofthe Itaya Pass remains a challenging section dueto its continuous sharp curves and heavy snowfall. In fact, 40% of train cancellations and delays on the Yamagata Shinkansen due to rain, snow, and collisions with animals occur between Fukushima Station and Yonezawa Station, including the Itaya Pass.
Therefore, although it remains unclear whether it will actually be realized, there is a plan under consideration to dig a long tunnel of approximately 23 km across the Itaya Pass to eliminate this difficult section of track. The tunnel construction would take 15 years and cost 150 billion yen, but it is expected to shorten the travel time for the "Tsubasa" train over the pass by more than 10 minutes and improve the stability of train operations, especially during winter. Whether the costs are deemed to outweigh the benefits will likely be the key to its realization.
Touge no Chikaramochi
At Toge Station, which was once a switchback station, a rare sight nationwide is now seen: street vendors selling their goods. The item being sold is "Toge no Chikara Mochi" (Toge Power Rice Cake). This daifuku mochi is made by "Toge no Chaya," a shop located near Toge Station, and consists of a pure white rice cake filled with smooth red bean paste.
The road near Toge Station is steep, so visiting by car is not impossible but quite difficult. Furthermore, the Yamagata Shinkansen "Tsubasa" does not stop at Toge Station, and only six local trains stop there in each direction per day, making a visit by train also challenging. However, the sight of street vendors selling their products and the deliciousness of Toge no Chikara Mochi (rice cakes) have made it a famous landmark of Itaya Pass, both in the past and present.
on the Shin'etsu Main Line, which was located on the border between Gunma and Nagano prefecturesthe UsuiPass (now defunct)Seno-Hachi Pass, has long been considered one of Japan's three most challenging railway gradients. As described in this article, people have struggled against this difficult pass, and it remains a challenging section even today. When you ride the Tsubasa train and cross the Itaya Pass, take a look at the scenery passing by the window. You will catch a glimpse of the harshness of nature and the history of the Ou Main Line's battle against it.
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