The construction of lines 4, 5 and 6 of the Riyadh metro comprises 64 kilometers of which 22.6 are underground.
- Line 4 (yellow): 6.22 kilometers was built by the “Cut & Cover” system.
- Line 5 (green), used two TBMs (Tunnel Boring Machines) to build a 13.7km line.
- Line 6 (purple): 3.12 kilometers of tunnel executed using the “Cut & Cover” system
It is the largest metro project in the developed world by a Spanish company.