This project consists of the construction of the North tunnel of the South bypass, measuring 4.20 km long, the M-30 ring road in Madrid between Paseo de Santa María de la cabeza and the junction with the road to Valencia (A-3), near Conde de Casal.
Of the 4,156 km of the South tunnel bypass of the M-30, 3,539 km were drilled by EPB (Earth pressure Balance) tunnelling machine "Dulcinea", which, at the time of the construction of the tunnel, was the world's largest, and the rest was performed between diaphragm walls.
The cross section of the tunnel drilled with the tunnelling machine comprises a platform consisting of three 3.50-metre wide lanes, hard shoulders measuring 0.50 m in width on either side and two pavements measuring 0.70 m in width with a 4.50 m gauge. This platform is based on prefabricated pre-stressed plates that separate it from a lower road measuring 4.80 m in width and 3.90 m in height, which serves as a rail and rescue service.
The North tunnel of the South bypass has emergency and evacuation galleries and four ventilation shafts.
The 107-metre long EPB tunnelling machine has two cutting wheels: the inner cutting wheel has a diameter of 7.00 m and the coaxial outer wheel has a diameter of 15.16 m. Both cutting wheels are mounted on the same level plane, allowing them to operate in clockwise and anti-clockwise rotations independently of each other.