The Tôkaidô Honsen (Tôkyô–Nagoya–Kyôto–Ôsaka–Kôbe) and its continuation, the San'yô Honsen, together form the principal artery of the Japanese railway system. "San'yô" stands for the sunny side of the Japanese mountains along the Inland Sea, in contrast to "San'in", the shady side of the mountains along the Japan Sea, which usually is colder and wetter. The San'yô Honsen, which links the cities of Kôbe–Himeji–Okayama–Fukuyama–Hiroshima–Shimonoseki (the latter located at the western tip Japan's main island Honshû), is 528, 1 km long, electrified with 1500 V DC and double track throughout (in parts double-double track). Actually the Kanmon Tunnel between Honshû (Shimonoseki) and the island of Kyûshû is also part of the San'yô Honsen, but it is operated by JR Kyûshû (☞ JR Kyûshû, Kanmon Tunnel).
Since the opening of the Shinkansen between Ôsaka and Okayama in 1972, and between Okayama and Hakata on the island of Kyûshû (via Shimonoseki) in 1975, the San'yô Honsen sees no more through express passenger traffic. Sleeping car services, which once used to be dominant on the San'yô Honsen, linking Tôkyô and the Kansai area with all important cities in Kyûshû, ended in 2009 (except for the connection Tôkyô – Takamatsu via Okayama, and Tôkyô – Izumo via Okayama, both operated by class 285 train sets). On the other hand, through freight traffic over the San'yô Honsen is heavy.
The section from Kôbe to Himeji (54, 8 km) is discussed separately. Kansai urban network trains from the Kyôto/Ôsaka/Kôbe area reach Himeji in the form of fast or accelerated services, and many continue from there at least to Aboshi (10, 3 km from Himeji). Twice an hour trains go on to Banshû Akô via Aioi (10, 4 km from Aboshi) and the Akô-sen.
While the coast line along the Inland Sea after Aioi is served by the Akô-sen, the San'yô Honsen traverses a sparsely populated mountain area and crosses the border from Hyôgo Prefecture into Okayama Prefecture on a pass route. At Kamigôri (just east of the pass and 14, 1 km from Aioi) the private main line of the Chizu Kyûkô branches off towards Tottori on the Japan Sea side. Chizu Kyûkô expresses bound for Tottori and Kurayoshi reach Kamigôri from Kyôto and Ôsaka, while a short JR express train from Okayama also travels from Kamigôri over the Chizu Kyûkô line to Tottori.
After leaving Kamigôri services at first are sparse (one train an hour) but get more frequent as we come closer to Okayama, 67, 9 km from Aioi.
Local trains from Okayama onwards as a rule operate as far as the large railway yard in the Itozaki/Mihara area (Okayama – Mihara: 89, 9 km). At peak hours there is a rapid service as far as Fukuyama, otherwise we see mostly 2 stopping trains per hour. Until Kurashiki, known for its beautifully preserved canal area and rice storehouses, local, express and freight trains heading for the Hakubi-sen and the Japan Sea use the San'yô Honsen; the distance from Okayama to Kurashiki is 15, 9 km. From here on the San'yô Honsen runs mostly through farm land, much of the way close the San'yô Shinkansen. Large industrial complexes dominate the scenery particularly around Fukuyama, reached after crossing the border into Hiroshima Prefecture. After Fukuyama the line approaches the coast of the Inland Sea, dotted with many larger and smaller islands which form a link over to Shikoku. In spite of numerous factories, particularly ship building companies, the little castle town of Onomichi has a particular romantic flair.
From Mihara to Hiroshima there are two railway lines, the Kure-sen, which follows the coast mostly through shipbuilding villages, and the San'yô Honsen, which now climbs up the valley to the plateau of Saijô and Hachihonmatsu. After Hachihonmatsu there follows a steep descent to Seno (22, 6 ‰ incline); in the opposite direction heavy trains need a banking locomotive for the climb from Seno to Hachihonmatsu (usually this locomotive runs from Hiroshima up to Saijô). From Shiraichi in the Saijô area – where also the University of Hiroshima is located – the line forms part of the Hiroshima urban network. Hiroshima is reached after a run of 71, 4 km from Mihara via the mountain plateau.
(text continued under "San'yô Honsen, Hiroshima – Shimonoseki")
