A radio access network (RAN) may be providing, in a coverage area, at least two access channels that are available for use by any wireless communication devices (WCD). Thereafter, the RAN may detect that a threshold load exists in the coverage area and responsively reserve one of the access channels for use only by authorized WCDs. In turn, authorized WCDs in the coverage area may be configured to use the reserved access channel to transmit access probes to the RAN, while unauthorized WCDs in the coverage area may be configured to use only a generally-available access channel to transmit access probes to the RAN. In this way, the disclosed methods and corresponding devices may limit the occupancy on the reserved access channel and thereby increase the likelihood that authorized WCDs can successfully access the RAN over the reserved access channel when the coverage area becomes congested.