High-speed running between Ankara and Eskişehir starts on March 13, 2009, according to this: http://hurarsiv.hurriyet.com.tr/goster/haber.aspx?id=10971133&tarih=2009-02-10
. This will require a new timetable; if anyone finds it on the Internet, I would appreciate a link. Thanks.
(8 March, 2009) According to http://www.todayszaman.com/tz-web/detaylar.do?load=detay&link=167998
, the intention is apparently to run eight trains per day in each direction between Ankara and Eskişehir. Reading between the lines, it looks as if these trains will shuttle back and forth between those two cities, rather than proceed to or from Istanbul. I have not managed to establish whether Istanbul-to-Ankara and vice-versa through trains will continue to run after March 13th or whether Istanbul-Ankara and vice-versa passengers will have to change train at Eskişehir. All information will be gratefully received.
(18 March, 2009) I have found the answer to my last question. Ankara-Istanbul and Istanbul-Ankara passengers now have to change from/to the new High-Speed Train at Eskişehir, according to this page on Turkish State Railways' official website: http://www.tcdd.gov.tr/yolcu/anahattrenleri.htm