Second Avenue Subway Project, New York: Design of New Underground Stations

The design of new underground subway stations in a complex urban environment will be discussed. Major topics covered will include both cut-and-cover structures and mined caverns, the factors in determining the applicability of each, and the main requirements and challenges of designing and constructing these systems in a highly constrained environment. The key determinants in the choice of the type of structure will be investigated. Loading, types of analysis utilized and constructability issues will be discussed. The discussion of cut-and-cover structures will include the use of both secant pile walls and slurry walls. The advantages, disadvantages, suitability and design considerations of each system will be examined. A key topic of discussion will be constructability issues related to these types of construction in a metropolitan area and the solutions that may be implemented. The close relationship with geotechnical data and its impact on geometry will be covered.