Moving underground for urban regeneration – Design challenges and cost assessment for the proposed undergrounding of Poseidonos av.

The evolution in underground construction has led to the development of many large-scale underground projects in which essential infrastructure are placed, and though this facilitating the preservation or even the reclamation of valuable surface space. A part of these underground structures is the subsurface transformation of road networks, aiming either at the better traffic regulation, or at the rehabilitation of the surface urban setting. However, special design requirements are needed along with the accurate costing of the proposed solution that would finally assess the feasibility of the project. The paper deals with the proposed underground relocation of a section of the Poseidonos av., a major coastal highway in Athens, as part of the greater urban regeneration that is going to take place in the Hellinikon area. The design of the 1.47 km underground section is proposed to be implemented as a cut-and-cover top down development that will inflict minimal traffic intervention during construction. Also, all proposed surface arrangements and configurations are presented, designed to ensure efficient transit to all users of the road and the surface area. Finally, the design details are used to draw accurate assessments of the required cost and time of the project that will completely transform the area and actually further boost the integration of the Hellinikon development project in the surrounding area.