Planning level tunnel cost estimation based on statistical analysis of historical data

Estimating the construction cost of a tunnel with certain diameter and length during the planning stage of a project is essential and a must do to justify the project, but it is a very difficult task. Numerous variables influence the cost of tunnel construction and limited information is available at early stages of design when the possible use of tunnels is being studied. Therefore, there is limited number of models at engineers' disposal for development of a proper cost estimate in tunneling projects. The focus of this study was to offer a model for estimation of the construction cost of tunnels for various applications in the preliminary stage of a project. The work is based on study of nearly 270 projects and statistical analysis of the recoded construction costs, tunnel size, ground conditions, and tunnel applications. Several cost estimation models are introduced for various tunnel types including waste water, water, and transportation tunnels in soft ground and rock. The model uses commonly available cost indices (CCI and BCI) to adjust the estimated costs for the time and location of the project. The proposed cost models presented in this study can included in a simple program to help users make more accurate and quick cost estimates for their future projects. The models do not deal with construction risk which is an essential part of the study of various methods and should be done through developing a risk registry with related cost of each case before final selection, design, and cost estimation of any tunneling project. (C) 2012 Elsevier Ltd. All rights reserved.