the poor condition and low carrying capacity of Iranian railroads, and the technical problems and the need of significant investments of Turkish railroads

This primarily concerns Eastern Turkey and the Iranian lines to the Turkish and Turkemen borders.

As I indicated in my diary, in Western Turkey there is significant improvement until 2010 (the Ankara-Istambul line is upgraded with French help as a 250 km/h electrified mixed-traffic double-track line until 2008 [+ I'd count a few years' delay], West of Ankara the first sections of line are well-built); while Iran recently finished the grand upgrade of its Eastern Tehran-Mashhad mainline, and upgrades to the West too.

_{*Lunatic*, n.
One whose delusions are out of fashion.}