As Tim correctly pointed out, it is a lower power system and you have to be fairly close to the park to hear it but it seems to work pretty well.
Parking is a separate company and the frequency is 453.000mhz which is either a DMR or NXDN. It's a great one to have on your scanner especially now with the problems with the new parking system they stupidly introduced this year. I just programmed all of them as conventional digital search and that seems to work just fine since AMFAM appears to be the only user anyway. Don't expect to hear much on non event days.