In Pavement ME, Version 2.5.5, why is there a tab for "PCC Longitudinal Cracking" calibration factors since longitudinal cracking prediction is not part of the current Pavement ME?
The PCC Longitudinal Cracking coefficients in Pavement ME Design correspond to the short jointed plain concrete pavement overlay of existing AC design type (SJPCP over AC). This design type and its calibration coefficients were introduced in version 2.3 in July 2016. These slabs are typically 5x5, 6x6, 7x7 thinner than conventional PCC designs. Their typical mode of failure is in the longitudinal direction.
I suspect that the longitudinal cracking calibration factors were included with the "New Rigid" calibration factors because the SJPCP design type does not fit well with the "Bonded Rigid" or "Unbonded Rigid" design types and their calibration factors. The bonded and unbonded factors are associated with PCC over PCC rehabilitation design types.