Tohid Tunnel is a tunnel in Tehran, Iran. It is about 3 km long, the third longest urban tunnel in Middle East.Tohid Tunnel broke construction records when it was opened in less than 30 months.The interior designs met the highest safety requirements. It includes installation of utilities equipment in the Tunnel, and manufacture and mobilization of north and south fans combined ventilation equipment, and control building and Niyayesh shaft. Major Work Item Quantities of Towheed Tunnel General Specifications