This study aims to use operational characteristics to help determine the size and the design of intersections on the basis of a targeted level of operation. This approach will allow for a preliminary evaluation of a broader range of possible designs, by screening out those designs considered less desirable or inappropriate on the basis of operational performance. This approach will also allow for a more objective comparison of all alternatives because all options target the same operational service level. The use of the critical lane analysis method was considered an appropriate approach for developing such size estimates for intersections. Similar methods for stop-controlled and yield-controlled intersections were also identified because it was necessary to expand these methods to include unsignalized designs as well. The Intersection Design Alternative Tool developed through this effort is capable of evaluating 13 intersection alternatives and identifying preferred lane configurations from more than 12,000 available configurations.