Shintetsu Ao Line

The Ao Line is above all a mountain commuter railway. Climbing out of the basin around Kobe into the hills to the west, it includes gradients as steep as 50 per mil (a fifty-metre rise over a kilometre) on the stretch between Suzurandai and Kizu, and curves as tight as a 200-metre radius — characteristics that have shaped its rolling stock and operating speeds ever since it opened.

The line began not with the Kobe Electric Railway but with a separate promoter, the Miki Electric Railway Company, which was incorporated on 29 June 1936. A railway licence for the corridor between the Kobe area and the town of Miki had earlier been granted, in 1928, to the Kobe Arima Electric Railway, and the building rights were transferred to the new Miki company. On 28 December 1936 it opened its first section, from Suzurandai to Hirono Golf-jō-mae, operating it at first with petrol railcars (DMUs).

Electrification followed quickly: the whole line was electrified and electric-train operation began on 15 April 1937. Later that same year, on 28 December 1937, the line was pushed east from Hirono Golf-jō-mae toward Miki, and the extension reaching Miki itself opened on 28 January 1938. The young railway thus linked the growing residential districts west of Kobe with the old castle town of Miki within about two years of its first train.

The operating company changed hands and names over the following years. On 9 January 1947 the Kobe Arima Electric Railway absorbed the Miki Electric Railway, and on 30 April 1949 the combined enterprise took the name Kobe Electric Railway. Under this banner the line was finally extended to its present western end: the section from Miki to Dentetsu-Ono opened on 28 December 1951, and the last stretch, from Dentetsu-Ono to Ao, opened on 10 April 1952, completing the through route. In the decades that followed the railway steadily upgraded the line to handle suburban growth — three-car trains from 1966, the new Nishi-Suzurandai Station in 1970, double-tracking of the busier inner sections between 1979 and 1989, a speed increase from 60 to 70 km/h in 1988, and works allowing four-car trains over the whole line by 2001.

From the late 1990s, however, the Ao Line entered a period of pronounced decline. Ridership, which had peaked at about 14.2 million passengers in fiscal 1992, fell to roughly 7.43 million in fiscal 2007 and 7.29 million in fiscal 2008 — barely half its peak — as the New Town communities along the line aged, residents retired, and the falling birthrate thinned the commuter base. The line ran in the red every year, with annual deficits exceeding one billion yen from fiscal 2001 and reaching a worst-ever 1.27 billion yen in fiscal 2006 and 2007; over the decade from fiscal 1998 to 2007 the accumulated deficit came to about 10.2 billion yen. The shortfall turned the line's survival into a public question, and from the mid-2000s the prefecture and the municipalities it serves stepped in with subsidies and a succession of regional public-transport plans aimed at keeping the Ao Line running.

• 19284 July: a railway licence for the corridor (Yamada-mura in Muko District to Miki-chō in Minō District) is granted to the Kobe Arima Electric Railway.
• 193629 June: the Miki Electric Railway Company is established to build the line.
• 193628 December: the Miki Electric Railway opens its first section, Suzurandai–Hirono Golf-jō-mae, operated with petrol railcars (DMUs).
• 193715 April: the line is fully electrified and electric-train operation begins.
• 193828 January: the line is extended east from Hirono Golf-jō-mae to reach Miki (at Miki Fuyūbashi), via Miki Higashiguchi opened 28 December 1937.
• 19479 January: the Kobe Arima Electric Railway absorbs the Miki Electric Railway (renamed Shin'yū Miki Electric Railway).
• 194930 April: the company is renamed the Kobe Electric Railway.
• 195128 December: the line is extended from Miki (Miki Fuyūbashi) to Dentetsu-Ono.
• 195210 April: the final section, Dentetsu-Ono to Ao, opens, completing the through line.
• 19705 June: Nishi-Suzurandai Station opens.
• 198231 October: the Nishi-Suzurandai–Aina section is double-tracked.
• 19882 April: with a timetable revision, the maximum speed is raised from 60 to 70 km/h.
• 198926 March: the Kawaike Signal Box–Kizu–Mitsu Signal Box section is double-tracked, completing the staged 1979–1989 duplication of the Kizu–Oshibedani area.
• 200123 June: improvement works between Ebisu and Ao are completed, allowing four-car trains over the whole line.
• 200330 November: one-man (driver-only) operation begins on the Suzurandai–Ao section.
• 20184 March: the building on the down-platform side of Miki Station is destroyed when a fire from a neighbouring blaze spreads to it; a reduced timetable runs until normal service resumes on 9 March.