A SIMPLIFIED THEORY OF KINEMATIC WAVES IN HIGHWAY TRAFFIC .2. QUEUINGAT FREEWAY BOTTLENECKS

For a freeway having various entrance and exit ramps, the methods desc ribed in Part I are used to relate the cumulative flow curve at any ju nction to the net cumulative entrance flow at this junction, and the c umulative flow curves for the freeway at the next upstream junction an d/or the next downstream junction. If the type of flow-density relatio ns typical of freeway traffic are idealized by a triangular shaped cur ve with only two wave speeds, one for free-flowing traffic (positive) and the other for congested traffic (negative), then the relationship is easy to evaluate. The cumulative flow curve at the junction is simp ly the lower envelope of a translation of the cumulative curve from up stream and a different translation of the cumulative curve from downst ream. This relationship is the basic building block for a freeway flow prediction model described in Part III.