Effective incident management requires the identification of incident severity and its potential impacts on the transportation system and its users.   This paper reports on an effort to develop methods to estimate the potential impacts of incidents on mobility and safety in real-time and to assign a severity index based on the estimated incident impacts and attributes.  The effort also includes the development of advanced visualization of incident impacts to further support effective incident management decisions.  The study includes the development and comparison of two models to assign an incident severity index to each incident based on estimated measures including lane blockage duration, average incident delay, queue length, and the potential for secondary incidents.  The derived measures and index can be used as additional indicators of incident impacts as part of traffic management center operations. The developed models are being implemented in conjunction with advanced visualization techniques as part of decision support tools to assist in operator decisions at a traffic management center in Florida.