ABSTRACT
The entire electrical installations of the two western shield Tunnel Boring Machines with their complex electronic controls were destroyed in the accident and had to be replaced. The causes of the damage were examined in detail by international teams of experts drawn from the consultants, the partners in the joint venture and independent experts. The requisite support pressure had been worked out beforehand using 3-dimensional flownet calculations on the digital geological model. This model was first designed on the basis of the probe drills carried out for the tender, and was subsequently refined with every new drilling operation and calibrated with every well or dewatering lance. A sophisticated infrastructure was required to deliver the requisite workforce, energy and building materials to all the worksites. The western tunnelling sites on the island of Sprogo were supplied from Halsskov using passenger vessels and barges. The work on driving the railway tunnel under the Great Belt was marked by numerous unusual setbacks.
