The classical Lighthill-Whitham-Richards (LWR) kinematic traffic model is extended to a unidirectional road on which the maximum density a(x) represents road inhomogeneities, such as variable numbers of lanes, and is allowed to vary discontinuously. The car density φ = φ(x, t) is then determined by the following initial value problem for a scalar conservation law with a spatially discontinuous ...

For a class of multidimensional linear perturbation problems of considerable significance in applications, the Poincarc-Lighthill technique is shown to give first-order expansion terms which grow unbounded relative to the leading term (secular behavior), while the method of linear time scales leads to well-behaved expansion terms. A solvable example is introduced for comparison with the exact s...