Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)


Civil Engineering

Committee Chair

Andrew Tarko

Committee Co-Chair

Samuel Labi

Committee Member 1

Nadia Gkritza

Committee Member 2

Bowei Xi


Traffic congestion and safety issues are pervasive in many urban areas across the United States due to the increasing traffic demand and evolving driving behavior. Microsimulation models can provide a reasonable estimation of operational performance analysis of intersections and interchanges. This dissertation used microsimulation to evaluate six alternative interchanges, as they may perform quite differently in different traffic and local conditions. Operational efficiency, agency and user cost and traffic safety are the major components for selecting the best alternative interchange. The existing microsimulation tool VISSIM was used to perform the operational efficiency, agency and user cost evaluations. A general concept of safety microsimulation is discussed which requires development of a new microsimulation tool. Using VISSIM, 13,500 traffic simulation experiments were carried out over a 24-hr period for 28 geometry cases and 200 traffic patterns. Statistical models were developed and presented in graphically for the simulated daily average delay, daily average stops, daily average stop delay, critical movement delay and maximum queue. Three performance measures were used to compute the additional vehicle operating, fuel consumption and traveler costs. The additional daily user costs of an interchange were presented as a function of the non-freeway AADT for various shares of off-ramp traffic. The agency costs were estimated based on the interchange bridge cross section, span length, earthwork, signalization, new ramp pavement, guardrail demolition, and structure removal. These performance measures will help to identify the traffic and/or geometric conditions that support the use of one type of interchange over another focusing on the traffic performance. The final selection should be supported with microsimulation of the preliminarily designed alternatives and supplemented with discussion of other implications. The local site conditions, user cost, construction cost, and safety considerations should be considered integral parts of the decision-making process.