The portal pit Engi is prerequisite for the construction of the Galgenbuck Tunnel . The portal is located on the weste of the Tunnel and represents the access for all excavation works. After the conclusion of the excavation works, a cut & cover tunnel will be built in this same pit, shaping the ground with its original form. The portal pit Engi is approximately 80 m long and 75 m wide. The maximum excavated height is approx. 22 m. The support walls are formed by separated or tangential bored piles Ø 80 and Ø 100 cm. The pile walls are supported with several layers of pre-stressed tendons whose forces are distributed by means of a longitudinal steel bracing. Due to the 6 year long duration of the works, the tendons had to be designed and executed as permanent tendons, i.e. with a full corrosion protection. Construction methods: Wall of separated piles with shotcrete reinforcement; Walls of tangential piles; Tendons with longitudinal steel bracing. Characteristic values: Total length excavated piles (Ø 800 and Ø1‘000 mm): 2‘350 m; Reinforcement of the piles: 99 to.; Pre-stressed tendons: 11‘000 m; Longitudinal steel bars: 77 to.; Passive anchors and nails: 540 m; Excavated material (rock and loose material): 44‘000 m³