Cambridge Systematics for the National Cooperative Highway Research Program, Project 8-36-62, September 2008 

"...Transportation Economic Development Impact System (TREDIS) is a web based evaluation system that is most notable for its distinctions between both freight and passenger benefits, and its simultaneous coverage of roadway, railroad, aviation, and maritime transportation. This economic analysis system evaluates how changes in transportation costs and accessibility relate to the operating requirements of various industries and resulting productivity and growth."

"…It has been noted that even local highway projects often have some impact on travel times and connectivity to airports, marine ports, intermodal rail facilities, or interstate highway interchanges. As a result, even single-mode projects can be considered from an intermodal connectivity perspective. That is the concept behind the TREDIS system that was used to evaluate how highway improvements would affect airport and marine port connectivity in both Portland, Oregon, and Vancouver, British Columbia."