The total length of the Isfahan-Shiraz railway, which is part of the Tehran-Bushehr-Asalouye national road, is about 500 km, of which about 130 km have been designed and supervised by this consulting engineers and have been in operation since 2008. One of the most important parts of it is located in Koli Kash Pass, where four tunnels have been built. Due to the high importance of the Isfahan-Shiraz railway route, the supervision of the pavement, signaling and communications of this project was entrusted to the consulting engineers of IranOSton