Geosynthetics are incorporated into flexible pavement systems to improve their performance. However, geosynthetics must be installed properly to produce good results. The application of discrete-event simulation to design and analyze the installation of geocomposite membranes in flexible pavements is discussed. Data collected from two test sections at the Smart Road project in Blacksburg, Virginia, were used for modeling and analy- sis. Stroboscope was used as the simulation engine. The process used in the development of simulation models is discussed. A number of installa- tion alternatives were studied and simulated to examine their practicality and to investigate their productivity, resource utilization, and unit cost. The United States highway system is rapidly deteriorating. Approx- imately $212 billion is needed to rehabilitate it (1). Stripping and spalling may occur because of the unavailability or ineffectiveness of the drainage layer when water infiltrates into hot-mix asphalt (HMA) pavement. A possible way to build more-durable and better highways is to incorporate advanced materials into them and to maintain free water drainage. Geosynthetics, for example, are among the new ma- terials used to improve flexible pavement performance. Geosynthet- ics can be divided into seven main categories: geotextiles, geogrids, geonets, geomembranes, geocells, geosynthetic clay liners, and geo- composites. The application of some geosynthetics as an interlayer in roads and highways has many benefits. Some types of geosynthetic are thought to prevent water infiltration, absorb stress between pave- ment layers, dissipate strain energy responsible for crack initiation, prevent intermixing of adjacent layers, and allow for good drainage. The use of geosynthetics may extend the service life of roads and highways. However, geosynthetics may not perform as intended if they are not installed properly. The installation process, a key factor in pavement performance, usually is overlooked, and this reduces the effectiveness of geosynthetics in pavement systems. The installation process must be designed so the geosynthetics are correctly placed, resulting in an effective life-cycle cost. Geosynthet- ics currently are installed in the field by trial and error, depending on the experience and intuition of contractors, or by following guidelines provided by FHWA or manufacturers, which usually do not address installation economics. Experienced contractors can make reasonable assumptions and perform quick calculations that result in acceptable initial installation procedures. A reasonable assumption by a contrac- tor, for example, would be to maximize the area of tack coat spray per pass to improve production. The contractor may not realize that this would allow some of the tack coat to cool to the extent that it loses its adhesiveness, and the contractor would have to spray another layer. This may result in too much tack coat, possibly leading to slippage. A simulation of the process can prevent this from happening by allow- ing the contractor to see the consequences of applying too much tack coat at one time. Errors like this are costly if discovered during actual installation, and the corrections that would be made quickly could lead to inefficiencies in other aspects of the operation. For installation processes that involve new technologies, these procedures can be quite inefficient. As the contractor performs an initial installation, the experience gained allows for significant improvements. Subsequent installations with the improved pro- cedure provide yet more experience that allows for even further improvements. Eventually, it is possible to arrive at installation pro- cedures that are reasonable. In cases in which many pieces of equip- ment are needed for installation and in which the process is complex and subject to variability, numerous iterations may be performed without a truly effective and economical installation procedure being reached. Contractors want to know the type, size, and number of machines that will make up the fleet. They want to know the production rate of the operation, the unit cost, and the utilization of their equip- ment. Ultimately, contractors want to be able to try many installation options and consider different parameters to find the best installation procedure, without spending much money. In essence, contractors would benefit from going through the iterative cycle of designing the operation, implementing it, gaining experience from it, and using the experience to redesign it, without actually investing the time and resources traditionally used in doing so. Computer-based discrete- event simulation allows this. This paper illustrates the use of discrete-event simulation for the design of installation procedures for a newly developed impermeable geocomposite membrane that may provide strain energy absorption in flexible pavements. DISCRETE EVENT SIMULATION A model is a representation of a real or imaginary system. Models can be studied, changed, and analyzed in an effort to better understand the system they represent. Experimentation with properly designed models may reveal how real systems would respond to real-world conditions. Discrete-event simulation is a computer-based model- ing and analysis procedure in which the state of the system is assumed to change only at specific, but variably separated, points in time. Discrete-event simulation has been used to analyze and design many construction operations (2–4). Use of Discrete Event Simulation to Design Geocomposite Membrane Installations Phuwanai Wanamakok, Julio C. Martinez, Imad L. Al-Qadi, and John A. Wilkes P. Wanamakok, J. C. Martinez, and I. L. Al-Qadi, Department of Civil and Envi- ronmental Engineering, Virginia Polytechnic Institute and State University, 200 Patton Hall, Blacksburg, VA 24061-0105. J. A. Wilkes, CARPI USA, Suite 100, 3517 Brandon Avenue, Roanoke, VA 24018. Transportation Research Record 1772 ■ 197 Paper No. 01-3129