Safety Considerations on Urban Roadway Tunnels (Case Study:‌Tehran Tohid Tunnel)

The high importance of the role of underground spaces in an urban transportation network as well as their great costs of construction and operation, has led their safety considerations to the foremost degree of importance. Tohid Tunnel is considered as one of the most significant urban civil projects in Tehran which, has faced with some incidents and events leading to non-safety of users and the tunnel structure during its operation. In this paper, studies have been conducted on the national and international codes and reports, presented for the purpose of the preservation of tunnel safeties. In this regard, some issues in Tohid tunnel have been recognized as opposed to safety criteria of tunnels which, in some cases could be resolved. Issues such as the possibility of fire occurrence, flood entrance, leakage of underground water and wastewater into the tunnel, collision of vehicles due to rather steep longitudinal slope of the tunnel, failure to comply with the driving rules by the users as well as inappropriate maintenance and repair of tunnel should be considered more greatly and significantly in order not to lead to unpleasant impacts. In general, keeping in mind of the mentioned issues in this paper, could prepare a pattern for other future tunnel projects, so that by gaining experience from Tohid tunnel, the reoccurrence of such similar issues could be highly prevented for other tunnels.