Underground projects are generally complex projects with many variables.
The most important factor in increasing the cost&time of the tunnel is the lack of sufficient studies before starting the project.

In special conditions, by changing the direction of the tunnel and reducing wedges, faults and micro-faults, groundwater, etc., even though the length of the tunnel increases, the cost and time can be reduced.

Studies during construction : 
During excavation, after examining the rocks and the condition of the layers, in some sections that are in good condition, to provide the ground for changing the initial maintenance of less expensive.

By modifying the implementation method For example, modifying the challenge pattern in the cutting zone and using a V-shaped cut at an angle of 45-50 degrees leads to increasing drilling steps, reducing the number of holes, explosives, reducing additional drilling and consequently reducing the cost of machinery, manpower and materials and time Run is done.