Updating the Decision Aids for Tunneling

The “Decision Aids for Tunneling” are a procedure and computer code that can be used to assess the effect on construction cost and time of geologic/geotechnical uncertainties and uncertainties in the construction process. Previously, it was only possible to make predictions prior to construction. There is, however, a need for updated predictions while construction is in progress. Such predictions can be used to improve scheduling, resource allocation, financial planning, and so on. This article presents an updating procedure that allows one to refine predictions during construction. Updating not only involves replacing the original prediction with actual data from the excavation, but also includes a learning component using information from the actual excavation to arrive at an improved prediction for the unexcavated part of a tunnel.