Trans-Iranian Railway

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For the national operator see Iran Railways

The Trans-Iranian Railway was a major railway building project started in 1927 and finished in 1939, under the direction of the Persian monarch, Reza Shah, to construct a basic network of railways joining the capital Tehran to the Persian Gulf and Caspian Sea. The Trans-Iranian Railway was built entirely by local capital. Trans-Iranian Railway is 1394 km long.

The first lines pass though formidable mountains, and international construction firms were heavily involved in the construction. Gradients up to 1 in 36 were required, plus hillclimbing techniques such as spirals were required.

1 Geological challenges
2 World War II
3 TV
4 See also

[edit] Geological challenges

All sorts of geological problems were encountered, which required abandonment of some tunnels, and realignment of the route through different terrain:

a tunnel though a salt dome had to be abandoned, as the disrupted water table would erode away the salt.
a tunnel commenced through apparently solid rock encountered powdery gypsum, which filled the excavation as fast as it was dug out - another abandoned tunnel.
a tunnel through pumice, was unblastable and undigable as the picks and shovels got stuck.
a tunnel enountered a void in the mountain, requiring a bridge in the middle of the tunnel.
poor fresh water supplies made mixing of long-lasting mortar and concrete problematic.
bridges like Veresk Bridge were unavoidable crossing Alborz mountains.

The principal lines were completed ahead of schedule and under budget, with the first train arriving in Tehran in about 1940.

[edit] World War II

During World War II, the railway was a vital component of the Persian Corridor supply routes connecting the Persian Gulf to Central Asia and the Soviet Union. The line was of such importance that the Allies imported rolling stock of its own design, including diesel locomotives such as the ALCO RSD-1.

[edit] TV

An exploration trip to find a cave dwelling fish named after a man called Smith, was filmed (by the BBC ?) travelling along this railway line, and some of the tunnels and deviations were visible.^{[citation needed]}