Hôhi Honsen 豊肥本線
Diesel motor coach 220-204 at Bungo Taketa. (2016)
Higo Ôzu, the end of the electrified suburban section. Electric two-car train 815-11 and the diesel train set 200-102 that will continue to Miyaji. (2013)
This line is also known as the Aso Kôgen-sen (The line across the Aso plateau), and it runs straight through the centre of Kyûshû, from Kumamoto in the west to Ôita in the east. On its way, the Hôhi-sen needs to climb up to and traverse the huge caldera of Mount Aso, an active volcano that erupts at regular intervals, the last eruptions having been in 2015 and 2016. The Aso caldera measures about 25 km from north to south, and 18 km from east to west. Inside the caldera, the line serves several agricultural settlements, passing along the foot of five major and several smaller volcanoes with their bizarre geological formations.
Starting in the west at Kumamoto, the Hôhi-sen operates as a suburban electrified line (electrified in 1999, 20 kV/60 Hz) to Higo Ôzu. From there starts the (non-electrified) climb up into the Aso caldera, first reaching the switchback station of Tateno; here the former JNR line to Takamori (now the private Minami Aso Tetsudô) branches off and runs along the southern foothills of the volcano. Trains on the main line reverse and tackle the very steep incline to a point high above Tateno. There trains reverse again and follow the outside of the caldera, before entering it through the opening created by the Shirakawa river. In only 6 km the Hôhi-sen climbs from an altitude of 277, 4 m at Tateno to 467,4 m at Akamizu.
After traversing the Aso caldera, the small town of Miyaji is reached. From here trains soon pass through the eastern caldera wall and begin their steep descent to Ôita via the town of Bungo Taketa, famous for its song "Moon over the Ruined Castle". The complete length of the Hôhi-sen is 148, 0 km.
The Hôhi-sen has been affected by torrential rain and storms ever since it was built (a large part in 1914) and completed in 1928 (the last section completed being the incline from Tamarai to Miyaji on the eastern side). The line was destroyed several times in recent years, and major interruptions of services were from July 1990 (interrupted for 15 months), September 1993 (8 months), September 2004 (3 months), July 2012 (2 months, but as the tunnels on the section between Bungo Taketa and Miyaji were internally destroyed, trains could not run here for 13 months). Again, in September 2017 part of the line on the eastern side could not be operated for a month.
The worst disaster to hit the line were the violent Kumamoto earthquakes of April 14, 2016 (foreshock) and April 16, 2016 (main shock, magnitude 7, 3). Following these quakes, which also derailed a train on the western side, the Hôhi-sen had to be closed down; the main section between Higo Ôzu and Bungo Taketa was out of use for a long period. Bungo Taketa to Bungo Ogi could be reopened on April 28, 2016, and Bungo Ogi through Miyaji to Aso on July 9, 2016. However, the rest of the line between Higo Ôzu and Aso, remains out of use for the time being. It is expected that Higo Ôzu to Tateno will reopen eventually, but the switchback line from there and the climb through Akamizu to Aso is destroyed through the spectacular collapse of the mountainside. At present, it is impossible to tell when – and even if – this part of the Hôhi-sen can be reopened, as the damage to railway line and road, particularly above and to the east of Tateno, is immense.
# Services between Bungo Ogi and Aso were reinstated in July 2016
Before the earthquake, services consisted of frequent commuter trains between Kumamoto and Higo Ôzu, and of local trains between Kumamoto and Miyaji at irregular intervals throughout the day. Between Bungo Taketa and Ôita the timetable shows a fairly regular service, but the section between Miyaji and Bungo Taketa was served only by 5 local trains a day. In addition, we had 4 express trains over the whole line and a few seasonal express trains from Kumamoto to Miyaji.
Today, the Hôhi-sen (apart from the commuter trains Kumamoto-Higo Ôzu) has fairly regular local services between Ôita and Bungo Taketa, with 3 to 4 local trains a day between Bungo Taketa and Aso, and an evening train between Bungo Taketa and Miyaji. In addition, 2 express services and 2 seasonal services are provided on the Aso to Ôita section. The line between Higo Ôzu and Aso remains closed.
The name of the line, Hôhi Honsen (Hôhi Mainline), derives from characters standing for the names of old provinces, namely Bungo (豊後), the old name of a large part of present-day Ôita prefecture, and Higo (肥後), the old name for what is now Kumamoto prefecture. The two characters 豊肥 together are pronounced "Hôhi". The border between Kumamoto and Ôita prefectures (i.e. between Bungo and Higo) runs through the east side of the Aso caldera, west of Bungo Ogi.
2016
- Destruction in the earthquake of 2016, April 14. April 17: Ôita - Bungo Taketa reopened. April 19: Higo Ôzu - Kumamoto reopened. April 28: Bungo Taketa - Bungo Ogi reopened. July 9: Bungo Ogi - Aso reopened.
2020, August 8: Aso - Tateno - Higo Ôzu reopened.