Metro tunnel Mashhad Urban Railway Line 3

Metro tunnel Mashhad Urban Railway Line 3

After the successful design of the bored tunnel for Mashhad metro line 2, the Mashhad Urban Railway Organization has asked Arthe Civil & Structure to carry out the engineering design for the bored tunnel of line 3 as well. This new line is 28 kilometers long in total and runs from west to east through the financial district and the historical city center.

Arthe performed the complete integral design of the tunnel lining, including the connections to the ventilation shafts and escape routes. In addition, a completely new settlement risk assessment has been set up.

Challenging route

The Mashhad Urban Railway Line 3 project is the third metro line. The route is characterized by a number of complicated and challenging passages of objects and adjacent structures (including crossings with previously constructed metro lines). As a result, the line had to be constructed at great depth over parts of the route and passes through a number of foundations of high-rise buildings at a very short distance. To be able to construct this, Arthe came up with a number of smart solutions for a safe execution of the tunnel.

As a basis for the design, we drew up a geotechnical design report with a geotechnical cross-section and a corresponding geotechnical parameter design set. In order to take into account the fluctuations of the depth of the tunnel and the geological variations, however still be able to produce an economical design, four different tunnel segments were designed. Pre-stressed elements are used at the subway stations, which were built afterwards. The design of the lining also included the technical specifications of the components to be poured in (dowels, guide rods, waterproofing, etc.).

Our activities in brief:

• Functional design based on the requirements of the client and stakeholders;
• Desk study, supervision and interpretation of the ground- and laboratory investigations;
• Design of the reinforced concrete segments for the tunnel lining, taking into account the loads from adjacent structures and sporadic construction at great depth;
• Engineering of the drilling processes and the support- and mortar pressures;
• Analysis of influences on the surroundings due to the drilling process and prevention measures for damage to adjacent structures.