Experience in Expert Estimation of Probabilities and Correlations for Rail Line Construction
Publication: Journal of Construction Engineering and Management
Volume 138, Issue 9
Abstract
To counteract cost escalation and delays in infrastructure construction, an estimation model has been developed that simulates project uncertainty with probability distributions, correlations, and disruptive events. When applied to a new rail line project, three model inputs were not available from the designers: time distributions, cost correlations, and probability of occurrence and cost/time impacts of disruptive events. Experts in the field of tunnel-, viaduct-, and earthwork construction were asked to estimate the unavailable information. This paper presents a brief overview of biases that occur when experts estimate probabilities, the calibration steps taken to prevent the experts from being affected by such biases, and example questions from the questionnaire, followed by an in-depth discussion of findings. Unexpectedly, the experts followed radically different estimation techniques: the tunnel expert recalled values from past projects, the viaduct expert calculated the required values, while the earthwork expert estimated the mode value, and from it, the extreme values. Depending on estimation technique, a bias influences or cannot influence an expert. It was also observed that experts not familiar with probability theory encountered major difficulties in correlation estimation, despite concept explanation and visualization. Thus, for a successful correlation estimation it is paramount that experts be acquainted with probability theory in addition to being knowledgeable in their fields.
Get full access to this article
View all available purchase options and get full access to this article.
References
Ayyub, B. M. (2001). Elicitation of expert opinions for uncertainty and risks, CRC, Boca Raton, FL.
Clemen, R. T., Fischer, G. W., and Winkler, R. L. (2000). “Assessing dependence: Some experimental results”. Manage. Sci., 46(8): 1100.
Cooke, R. (1991). “Experts in uncertainty: Opinion and subjective probability in science.” Environmental ethics and science policy series, Oxford University Press, New York.
Hallowell, M. R., and Gambatese, J. A. (2010). “Qualitative research: Application of the delphi method to CEM research.” J. Constr. Eng. Manage., 136(1): 99–107.
Moret, Y. (2011). “Modeling cost and time uncertainty in rail line construction.” Ph.D. thesis, Massachusetts Institute of Technology, Cambridge, MA.
Moret, Y., and Einstein, H. H. (2012). “Modeling correlations in rail line construction.” J. Constr. Eng. Manage., 138(9), 1075–1084.
Information & Authors
Information
Published In
Copyright
© 2012 American Society of Civil Engineers.
History
Received: Dec 16, 2010
Accepted: Nov 1, 2011
Published online: Nov 3, 2011
Published in print: Sep 1, 2012
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.