Why not simply post a lower speed limit and have the police enforce it?
Posting speed limits lower than the 85th percentile speed does not result in voluntary motorist compliance with the posted speed limit unless there is strict, continuous and visible enforcement. Increased enforcement is effective only at the immediate time and in the area where the police officer is present. The availability of police officers is limited and their services must be shared with other police responsibilities. If unusually low speed limits are not vigorously enforced, they will be consistently violated and will breed disregard for speed limits in general.
