We examine various realistic generalizations of the basic cellular automaton
model describing traffic flow along a highway. In particular, we introduce a
{\em slow-to-start} rule which simulates a possible delay before a car pulls
away from being stationary. Having discussed the case of a bare highway, we
then consider the presence of a junction. We study the effects of acceleration,
disorderness, and slow-to-start behavior on the queue length at the entrance to
the highway. Interestingly, the junction's efficiency is {\it improved} by
introducing disorderness along the highway, and by imposing a speed limit.Comment: to appear in J. Phys. A:Math.& General. 15 pages, RevTeX, 3
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