An experimental setup consisting of 12 layers of glass Resistive Plate Chambers (RPCs) of size 2,m,$times$,2,m has been built at IICHEP-Madurai (ang{9;56;14.5},N ang{78;00;47.9},E, on the surface) to study the long term performance and stability of RPCs produced on large scale in Indian industry. This setup has been collecting data triggered by the passage of charged particles. The measurement of the multiplicity of charged particles due to cosmic ray interactions are presented here. Finally, the results are compared with different hadronic models of the CORSIKA simulation.