  In a Monte Carlo study the conductivity of two-dimensional random stick
systems is investigated from the percolation threshold up to ten times the
percolation threshold density. We propose a model explicitly depending on the
stick density and junction-to-stick conductance ratio. The model describes the
transition from the conductivity determined by the structure of a percolating
cluster to the conductivity of the dense random stick networks. The model is
motivated by the observed densities of the sticks and contacts involved in the
current flow. The finite-size scaling effects are also included in the
description. The derived model for conductivity should be broadly applicable to
the random networks of the rodlike particles.
