Requires posted speed limit on certain limited access highways be based on speed at which 85 percent of vehicles are traveling; designated as Speed Limit Sanity Act.

This bill requires that speed limits on state-managed limited access highways (like major interstates) be set based on the speed at which 85% of vehicles are traveling, rather than arbitrary standards. It mandates a traffic engineering study and speed survey to determine these limits, replacing current default settings. Until a study is completed, fines for speeding violations on these highways would be reduced to $20 per offense (down from standard penalties). The law directly affects drivers and state highway authorities managing eligible limited-access roads, focusing on aligning posted speeds with actual traffic flow patterns.