Stroboscope: State and resource based simulation of construction processes.

Abstract

Construction processes range from the very simple to the very complex. Complex processes are difficult to analyze and optimize using standard mathematical methods. Simulation is an alternative method of analysis that offers numerous benefits. The construction simulation systems previously available could not model typical construction processes with the necessary level of detail. General purpose simulation systems, generally based on the process interaction strategy, cannot easily model the multiple resource requirements and dynamic complexity of construction processes. The purpose of this research was to remedy this situation and address the simulation modeling requirements of construction processes. The end result of this effort is Stroboscope, an acronym for STate and ResOurce Based Simulation of COnstruction ProcEsses. It is a general purpose simulation programming language specifically designed to model construction operations of any complexity. Stroboscope models consist of a series of programming statements that define a network of interconnected modeling elements, give the elements unique behavior, and control the simulation. Stroboscope's ability to dynamically access the state of the simulation and the properties of the resources to define model behavior differentiate it from other construction simulation tools. The state of the simulation refers to such things as the number of trucks waiting to be loaded; the current simulation time; the number of times an activity has occurred; and the last time a particular activity started. Access to the properties of resources means that operations can be sensitive to resource properties--such as size, weight, and cost--on an individual (the size of the specific loader used in an operation) or an aggregate basis (the sum of the weights of a set of steel shapes waiting to be erected). Model behavior is defined through attributes attached to modeling elements, such as the duration or priority of an activity; the discipline of a queue; and the amount of resource that flows from one element to another. Most attributes are defined with dynamic expressions that can access the state of the simulation and the properties of resources. Stroboscope can model uncertainty in any aspect of the real system being represented (and not just time) such as stochastic resource production or consumption. Stroboscope models can select the routing of resources and the sequence of operations dynamically; allocate resources to activities based on complex selection schemes; combine resources and dynamically assign properties to the resulting compound resource; and activate operations subject to complex startup conditions not directly related to resource availability.