You are almost certainly aware of the posted speed limits that appear on most roads. You probably also know about the potential consequences if you violate them by driving too fast or, in some cases, too slow. You may also be aware of statutory speed limits that state governments set to apply to certain roads where no posted speed limits appear.
“Special conditions” speed limits supersede both of these. According to the Federal Highway Administration, these speed limits apply when circumstances exist that make the regular speed limits unsafe. There are several types of “special conditions” speed limits, which can be temporary or permanent.
Variable speed limits
These speed limits apply to a situation that requires a reduction of speed for a limited amount of time. For example, if traffic is particularly heavy, weather is unfavorable or there has been an accident, a variable speed limit may remain in force while the condition persists. You often become aware of variable speed limits from a display on a changeable message sign along the side of the road.
School zone speed limits
Children do not always abide by traffic safety rules, especially when they are young and still learning them. Therefore, the responsibility for their safety shifts to you, the driver. To give you time to see children in the street and avoid hitting them, school zones often have reduced speed limits ranging from 15 to 25 miles per hour. These may be permanent but only enforceable during school hours.
Work zone speed limits
These are in place in areas where road construction is going on. The special condition lasts until the work is complete. Work zone speed limits are for the protection and safety of drivers and workers alike.
Authorities take “special conditions” speed limits very seriously. The penalties for violating them may be much higher than for regular speed limits.