In 1996, the NCDOT increased the speed limits on interstate highways and full control access facilities to as high as 70 mph. Studies have shown that the increased speed limits result in travel speeds typically a few miles per hour above the posted speed limit. An earlier study conducted by NCDOT shows that increased speed limits also increased speed creep, the gradual increase of travel speeds.
In 1998, NCDOT implemented a program to save lives by preventing across median crashes by providing positive barriers on all freeways with median 70 feet or less. The barrier seals off the median with limited openings for maintenance at transitions near bridge piers in the case where cable barrier is installed. The lack of breaks limit the locations where emergency vehicles and law enforcement officers can turn around. The respective agencies claim that the barriers adversely affect their ability to perform their duties.
The results of the project should provide NCDOT with objective measures concerning the effects of continuous median barriers on speeding, speed-related crashes, response and transport times. This allows the department to establish performance-based policies concerning this critical safety issue.
