This paper is an investigation of the relationships among speed, flow, and occupancy, representing the three variables of traditional theory for uninterrupted traffic flow. The variables were examined in three-dimensional space, rather than two at a time as has previously been the case. Scatter plots showing connected data points were positioned in space using a three-dimensional rectangular co-ordinate system. Oblique views of the data were projected as two-dimensional plots for presentation purposes. The resulting pictures were evaluated for points of agreement with traditional traffic flow theory and with a possible new approach based on the Cusp catastrophe theory. The results suggest that conventional theory is insufficient to explain the data and that the plotted data are visually consistent with the catastrophe theory model of uninterrupted traffic flow.
Samenvatting