Laguna Madre is located on the southern shore of the state of Texas. The Gulf Intracoastal Waterway (GIWW) passes under the Queen Isabella Causeway between Port Isabel and South Padre Island. In 2001, a tow struck the Queen Isabella Causeway collapsing a span of the bridge and resulting in the death of eight motorists. In response to that event, the U.S. Army Engineer District, Galveston, (SWG) was tasked with making channel improvements that would provide for safer navigation through the Queen Isabella Causeway. To assist SWG in evaluating alternatives for the proposed channel improvements, the U.S. Army Engineer Research and Development Center (ERDC) conducted a navigation study utilizing realtime ship simulation modeling. Model development and online testing occurred at the ERDC Waterways Experiment Station (WES) in Vicksburg, MS during the period from August 2005 to May 2007.