Verification of Trip Generation and Trip Internalization Estimation Procedures for Mixed-Use Developments

Mixed use developments (MXDs) are a design alternative consisting of master planned projects encompassing diverse and complementary land uses in close proximity. In order to adequately assess the potential benefit MXDs at planning stage, a sound trip estimation method should be established. It is expected that the total external traffic for the MXDs will be less than that resulting of adding the traffic generated by the individual land uses when considered in isolation. This trip reduction is referred to as internal trip capture and it is the basis for site-specific methods such as those established by the Institute of Transportation Engineers (ITE). The performance of site-specific methods for MXDs is heavily influenced by the quality of data on internal trip capture. However, data on internal trips are not collected as frequently as free-standing land use trip generation rates. This article presents the results of an internal trip capture study performed on four sites in Florida. The study was aimed at gaining further insights on the internal trip capture behavior in MXDs and how it influences the traffic that impacts on the public roadway system (external trips).The results obtained confirmed that traditional methods significantly overestimate the trips generated by MXDs. In addition, the study served as a confirmation of a recently proposed methodology to improve traditional trip estimation method for MXDs. The results of the study were joined with the existing studies for a more comprehensive data set on internal trip capture. Comparison of different methods and recommendation for implementation are also provided.