  We have obtained the random loose packing fraction of the parking lot model
(PLM) by taking the limit of infinite compactivity in the two-variable
statistical description of Tarjus and Viot for the PLM. The PLM is a stochastic
model of adsorption and desorption of particles on a substrate that have been
used as a model for compaction of granular materials. An order parameter $\rho$
is introduced to characterize how far from a steady state situation the model
is. Thus, configurations with $\rho<1$ age. We propose that $\rho$ can be a
starting point in order to stablish a connection between Edwards' statistical
mechanics and granular hydrodynamics.
