  The s2s-OVCA is a cellular automaton (CA) hybrid of the optimal velocity (OV)
model and the slow-to-start (s2s) model, which is introduced in the framework
of the ultradiscretization method. Inverse ultradiscretization as well as the
time continuous limit, which lead the s2s-OVCA to an integral-differential
equation, are presented. Several traffic phases such as a free flow as well as
slow flows corresponding to multiple metastable states are observed in the
flow-density relations of the s2s-OVCA. Based on the properties of the
stationary flow of the s2s-OVCA, the formulas for the flow-density relations
are derived.
