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When the power system of the Chur-Arosa-Bahn (the older, but more widely known name) was changed from 2400 V DC to the RhB main line's AC system (11 kV, 16 2/3 Hz) after nearly 63 years, this was a major event which was noticed all over Switzerland (cf. clipping from “Der Bund,” Bern, Dec. 01, 1997). For me, it was the reason to have a closer look at this line. |
The Chur-Arosa-Bahn (ChA), whose end stations lie 25.7 km apart with a difference in altitude of 1155 m, was opened to the public on December 11, 1914. In spite of the fact that WW I had already begun, it was decided that the opening was necessary for the winter tourist season in the city of Arosa. The ChA was built in very short time; the definite plans date from March 14, 1912!
The importance of the ChA for the region can hardly be overestimated; Arosa is most probably the only major Swiss tourist area where more than 50% of all guests arrive by train. In 1996, 600,000 passengers and 40,000 tons of goods were transported by the ChA; since its opening, the ChA has probably transported more than 35 million passengers.
The ChA may be less spectacular for the casual observer than the Bernina line, but it was not less demanding for the engineers who built it: Only 4 km of the line are on even ground, but 70% have a gradient of 60‰. 12.4 km, i.e., nearly half the line's total length, are on curved track, 7 km of these with a minimal radius of 60 m (RhB main line: 100 m). If you consider that 7% of the total length of this line extend over 35 bridges and viaducts and 9,6% (2,34 km) of the track are laid in 18 tunnels, it becomes clear why the ChA was the most expensive line of the RhB.
In a statistical overview that dates from 1938, we find the total cost that had been invested in the different lines up to this time. These were
| 76,700 | Swiss Franken per kilometer for the Bellinzona-Mesocco line, |
| 256,900 | Swiss Franken per kilometer for the Bernina line, |
| 343,000 | Swiss Franken per kilometer for the main line, and |
| 402,700 | Swiss Franken per kilometer for the Chur-Arosa-Bahn. |
The probably best known building along this line is the Langwieser Viadukt which was one of the first large structures in the world built of reinforced concrete. The largest arch of this 287-m-viaduct has a diameter of 100 m, the viaduct has a total height of 62 m. For its construction, 7500 m³ of concrete and 330 (metric) tons of iron were needed.
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| The Langwieser Viadukt on a hand-coloured postcard from the year 1918 |
Based on the treaties signed on October 24/25, 1941, the ChA was taken over by the RhB as of January 1, 1942. Though this improved the economic situation of the cities of Chur and Arosa and the communities in the Schanfigg, it meant more financial burdens for the RhB, the canton (state) of Graubünden and the Swiss Federal Government.
Soon after this unification of RhB and ChA, it was discussed to adapt the ChA to the RhB main line's AC power system. This idea, however, was not pursued as the one-phase-AC supply would have caused problems; furthermore, the ChA's six DC motor coaches were still in excellent condition.
Only fifty years later, in the nineties, plans for re-structuring the ChA were discussed again. Besides changing the power system to AC, plans were considered to lead the line, which passes directly through the city of Chur since 1914 (cf. postcard below), through a tunnel.
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| The Plessurquai in Chur with a ChA motorcoach in the year 1918 |
Construction of the 5 km Mittenberg-tunnel would have cost 310 million Swiss Franken; the advantages, however, would have been moderate: The tunnel would have saved only some minutes on the Chur-Arosa route and would have brought some improvement to the traffic situation in Chur. In autumn 1996, this project was definitely discarded because of the enormous cost.
Adaptation of the power system to the main line's AC system, however, was performed according to plan: On November 29, 1997, the DC era ended with the arrival of train No. 624 on the station square in Chur. On the same day, the “AC era” began on the Chur-Arosa line when a new train, the Arosa-Express with newly designed coaches, began its operation on this line.
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| Arosa-Express in the Chur station square | Arosa-Express control car |
| (Pictures Copyright © G. Deambrogi, used here with permission) | |
Meanwhile, the Arosa-Express has become a “trademark“ of the RhB comparable to famous other trains like Bernina Express and Glacier Express.
What happened to the old DC motorcoaches? Unfortunately, ABDe 4/4 No. 481, 482, 483, and 485 were scraped in Untervaz. No. 484 and 486 were transported from Landquart to France on November 25, 1998; they came to the → La Mure tourist railway near Grenoble. The last two motorcoaches, No. 487 and 488, came to the Chemins de fer du Jura (→ CJ) in autumn 1999. In the CJ main depot in Tramelan, they were converted from 2400 V to this line's 1500 V system; since early 2000, they are used for waste container trains.
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From 2004 until late 2007, the station square in Chur didn't look very inviting. A redesign of the whole area also involved the Arosa line station; operation, however, was not impaired. (The pictures were taken in the autumn of 2005.)
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| Now that the work is done, the Arosa line has a neat little station! (January 31, 2008) | |
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References:
Copyright © 1998–2008 and responsible for contents: Christoph Ozdoba.
First version January 11, 1998, last edited February 18, 2008.
