 This led to the widespread but misleading belief that no limit applied, and that derestriction signs indicated an "unlimited" limit.This belief, coupled with repeated studies showing 85th percentile speeds in excess of on major routes, comparatively high road tolls, difficulty in prosecuting speeding offences, and the variance in meaning of the derestriction sign across states, led New South Wales to harmonise its rural default limit to in 1978.The use of derestriction signs in New South Wales was officially discouraged, and on state controlled routes, signs were progressively used instead.