Very High Speed For Turkey

On 14 April 2023 the Turkish Transport Minister, Adil Karaismailoğlu, revealed preliminary details of the proposed new high speed line which will link Istanbul and Ankara. The existing high speed route, built between 2005 and 2014, enables a fastest time of 4 h 05 for the 533 km. However, if the new line is built, this will be reduced to 1 h 29. 

The new 344 km, 350 km/h line will diverge from the existing one at  Adapazarı, then serve Sakarya, before tunnelling under the Bolu mountain range to Nallıhan, and finally to Ankara. It will have 52 tunnels totalling 120 km, and 19 viaducts, totalling 14 km. 

This is not the first time such a railway has been planned. The first project dated from 1943, when a new fast railway was envisaged between Istanbul and Ankara, to shorten the distance between the two cities from 576 km to 416 km and to reduce journey time from 7 h 30 to 2 h 30. Then in the early 1970s a 280 km line was proposed between Arifye and Sincan, reducing the distance between Istanbul and Ankara by 118 km. 

Some work, including the boring of the 10 km long Ayaş tunnel, took place, but the project was abandoned after the 1983 General Election, the new government deciding instead to invest hugely in road network improvements. In 1991 the scheme was revived, and about 8 km of the tunnel were completed, work once again being halted after the 2002 General Election. 

At present both portals of the tunnel have been walled up. Studies have shown that it has an inadequate cross-section to withstand the pressure created by the passage of high speed trains. However, the tunnel is still in the hands of the contractor that started boring it in 1976 - Nurol Construction, which laid an access railway to one portal.

Various other sections of trackbed were built. For instance, if you examine google Maps in Sincan, the route of the unfinished railway can be seen extending west of the present station (terminus), passing south of Yenikent in tunnel, and then continuing across open countryside to the Ayaş tunnel, north of Eskişehir.