Purpose of this study is to assess the environmental impacts from transportation of radioactive materials in urban environs. The impacts from accident-free transport, vehicular accidents during transport, and from other abnormal situations are analyzed. The approach is outlined including description of the models developed and the data bases employed to account for the special features of the urban environment. The operations and contributions of the task group formed to assist in this study are also discussed. The results obtained for the New York City study area are presented and explained.