Abstract
The characteristics of preincident, postincident, and nonincident traffic conditions on freeways are investigated. The characteristics are defined by second-order statistical measures derived from spatiotemporal speed contour maps. Four performance measures are used to quantify properties such as smoothness, homogeneity, and randomness in traffic conditions in a manner similar to texture characterization of digital images. With real-world incident and traffic data sets, statistical analysis was conducted to seek distinctive characteristics of three groups of traffic operating conditions: preincident, postincident, and nonincident. The study results showed that the spatiotemporal characteristics of each of the three groups were not discernible. Although the distributions of performance measures within each group are statistically different, no consistent pattern was detected to imply that certain characteristics could increase the likelihood of incidents or identify precursory conditions to incidents.
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