The ever increasing demand on the air transportation system is causing a lot of congestion and delays, leading to large monetary losses and passenger inconvenience. This has prompted the development of many analysis tools to help the understanding of the airport system where some improvements could be performed to enhance the capacity of the airports. The Center for Transportation Research at Virginia Tech, in line with the FAA’s Capacity Enhancements Plan, is developing strategies to alleviate the airport congestion problem by developing a model (REDIM) to design and optimally locate high-speed exit taxiways. The objective of this research is to develop a computer simulation model to predict the airport capacity enhancements due to the above mentioned high-speed exit taxiways and as well as due to other changes in operational procedures, aircraft characteristics, airport environmental conditions, etc. RUNSIM (RUNway Simulation Model), a discrete event simulation model was developed using SIMSCRIPT 11.5 language. This model simulates dual operations on a single runway, with capabilities of simulating FAA standard and REDIM designed high-speed exits, variable intrail separations, different aircraft mixes, and weights, arrival rates and patterns, etc. Currently it has a 30 aircraft data base to perform the simulation. Its output includes such global statistics as total arrival and departure delays, weighted average ROT and its standard deviation, aircraft exit assignment table, arrival and departure event lists. It has the capability to perform multiple iterations on a single application, which helps in performing statistical analyses on the results for better inference. / Master of Science