The Route 9A reconstruction project on the west side of Manhattan, New York City, required the projection of trip generation by land uses that would be developed by the project build year and beyond. Because new development would vary greatly in its accessibility to public transportation, socioeconomic character, size, and other attributes, it was decided that available, standard trip generation rates were inadequate to capture trip generation variations within a major land use category. In Manhattan, residential and office land uses account for 75% of existing developed square footage and 90% of the new square footage to be developed by the build year. By isolating zones of pure residential or office land use (95% of developed square footage in the respective land use), it was possible to analyze existing trip generation rates developed from origin-destination surveys and to infer trip generation rates. These rates were correlated with various zone characteristics such as subway access to develop formulas and trip generation rates that more accurately capture the trip-generating characteristics of developments in various locations. The trip generation rates developed are currently in use on the Route 9A project.