The local road authority can post these plates in work zones on local roads. These speed limits range from 20 mph to 40 mph and can be posted by the local road authority in active work zones on local roads. The work zone plate is black and orange and the speed limit sign is black and white. Temporary construction zone speed limits are regulatory speed limits established for long term construction projects or detour routes. These black and white signs are used when a reduced speed is needed for driver safety.
Studies show that there is little change in the speed pattern after the posting of a speed limit.
The driver is much more influenced by the roadway conditions. Although lowering the speed limit is often seen as a cure-all in preventing crashes, this is not the case. Crashes are most often the result of driver inattention and driver error. This speed variance can contribute to crashes. A uniform speed of vehicles in a traffic flow results in the safest operation.