Honk effect in the two-lane cellular automaton model for traffic flow

In real traffic, when a vehicle is hindered by its preceding vehicle and simultaneously it cannot change lane, it may honk the horn. As a result, the driver of the preceding vehicle may change lane to make way for it. However, this effect has seldom been investigated before. In this paper, we take this issue into account by proposing a new symmetric two-lane cellular automaton model. It is shown that the honk has almost no effect in the homogeneous traffic whereas it enhances the flux in the intermediate density regime for the heterogeneous traffic. We suggest that this is because the occurrence probability and the lifetime of the plug are suppressed due to the introduction of the honk. Finally, we argue that the honk behavior is not encouraged in the asymmetric two-lane model. (C) 2004 Elsevier B.V. All rights reserved.