The State of Computer Simulation Applications in Construction

Introduction

Simulation is one of the techniques that has been used to model uncertainties involved in construction operations. Although simulation is a powerful tool for modeling construction operations, the application of simulation is still limited in the construction domain. This has generally been attributed to the difficulty in learning and applying simulation languages to industry (Sawhney and AbouRizk 1996, Oloufa et al 1998, Touran 1990). The simulation process is an iterative process which involves different steps. It has been defined as “imitation of a real-world process or system over time” (Banks et al 2000). Modeling construction operations utilizing discrete event simulation, requires the modeler to define three main elements (Schriber and Brunner 1999): project, experiments and replications (see Figure 1). A “project” is performed to study a certain operation which has specific characteristics, for example, an earthmoving operation that contains a definite scope of work and specific road characterisitics. An “experiment” represents one alternative of the project under consideration by changing the resources assigned for the execution of the project and/or its individual activities. A “replication” represents one execution of an experiment within the project.

Figure 1.

Elements of discrete event simulation

Modeling utilizing simulation can be applied either in a general or special purpose simulation environment. General purpose simulation (GPS) is based on formulating a simulation model for the system under study, running the simulation and analyzing the results in order to decide whether the system is acceptable or not. In case of being unacceptable, the process is re-iterated and a new alternative system is considered. Different GPS software systems have been developed for a wide range of industries: AweSim (Pritsker et al 1997) and GPSS/H (Crain 1997); for construction: Micro-CYCLONE (Halpin and Riggs 1992) and STROBOSCOPE (Martinez 1996). Special purpose simulation (SPS) is based on creation of a platform or a template for a specific domain of application (Marzouk and Moselhi 2000, AbouRizk and Hajjar 1998). The steps for simulation, in this case, are the same as in the GPS case except for the first step (construct simulation model) since the platform has the characteristics and behavior of the system under study. Also, the modification is limited to the input parameter(s) of a pre-defined system and not to the characteristics and behavior of the system. This chapter presents a state of computer simulation applications in construction. Then, it describes in details two construction applications that have been modeled using computer simulation. These applications are earthmoving and construction of bridges decks.