When some two-lane roads with 55 mph speed limits are widened to four through lanes, curb and gutter is installed to address issues such as access control, difficult terrain, and limited right-of-way. Posted speed limits along such highway segments are typically decreased to 45 mph in North Carolina because of guidance in the AASHTO “Green Book” and elsewhere that vertical curbs should not be placed next to high-speed lanes. In spite of those expensive improvements, the results may be viewed negatively by the public, design professionals, and law enforcement personnel. Drivers may suffer from getting tickets or driving slower, designers may be blamed by the public, and the police may face an increased enforcement burden.To help resolve this dilemma, in this research the team collected relevant data such as speeds and collisions on four-lane road sections with curbs which have 45 or 55 mph speed limits and non-traversable medians or two-way left turn lanes. The team found that the speed limit does not seem to make an important difference in the collision rates or severities for the roads the team examined. The higher speed limit also made relatively small differences in the mean speeds and speed variances observed. Considering all of the results, the researchers recommended that the NCDOT continue its current policy of allowing 55 mph speed limits on four-lane roads with curbs on a selective, case-by-case basis. The team suggested a list of things to consider when making decisions about posted speed limits in such cases.