### Authors

Photios
G. Ioannou
& Julio C. Martinez

Civil & Environmental Engineering Department

University of Michigan

Ann Arbor, Michigan 48109-2125, U.S.A.

e-mail: photios@umich.edu

### Abstract

The comparison of alternative construction methods is one of the principal
reasons for using simulation to model construction processes. The efficiency and
effectiveness of such comparisons can be greatly improved by the prudent use of
"matched pairs," a variance reduction technique based on dedicated and
fully synchronized random number streams. The basic methodology is illustrated
by using the Stroboscope simulation system to compare two alternative
construction methods for rock tunneling (*Conventional
vs. the NATM*). For this example the effects are dramatic. The
probability of choosing the less expensive construction method based on a single
run increases from 55% to 96%, the variance of the difference in cost decreases
by two orders of magnitude, and the 95% confidence interval for the expected
difference in cost given by 4,000 independent pairs is given by only 7 matched
pairs.

### Keywords

STROBOSCOPE, construction, simulation, modeling, tunneling, NATM, variance
reduction, random number streams, common random numbers, design of experiments,
comparison of alternatives.

### Availability

Ioannou P.G., Martinez, J.C., "Evaluation of Construction
Alternatives Using Simulation," ASCE, 440-447, * Construction Congress
95*, San Diego, CA, October 22-26, 1995

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This page last updated 02/16/18
, by P.G. Ioannou