1. The density factor in traffic flow;Greenshields;Traffic Engineering,1960
2. Interdependence of certain operational characteristics within a moving traffic stream;Athol;Highway Research Record,1965
3. Uniform criteria for level of service analysis of freeways;Lin;Journal of Transportation Engineering, ASCE,1996
4. Evaluation of speed estimated made with single-detector data from freeway traffic management systems;Hall;Transportation Research Record,1989
5. The Relationship between occupancy and density;Hall;Transportation Forum,1986