A traffic lock is an automatic lock placed on a road segment based on the volume of traffic that traverses the segment. An editor may lock a segment to a rank which is higher but not lower than the traffic lock.
calculation
world
USA
Traffic locks are not (yet) implemented in the USA. Details are being worked out. No segment should be automatically locked to rank 6. We're seeking immunity for AMs within their managed area and don't intend to sign off on activating traffic locks unless this is achieved one way or another. Unlocking roads for a lower ranked editor is not possible.