RALEIGH, N.C. — On some stretches of highway, the posted speed limit is 55. On other parts, it is 65. It can be as high as 70 in even other sections.

Who sets the speed limit, anyway?

"The important thing about speed limits is that they are reasonable, and the general publis respects them, and that we follow through on them," said Kevin Lacy, of the Department of Transportation.

Lacy manages the Traffic Safety Unit with the DOT's Traffic Engineering Branch. He said local engineers make the recommendations for the speed limits. The state traffic engineer -- whom Lacy works for -- approves or disapproves the speed limits.

"There is no one rule that fits everything," Lacy said. "It would be ludicrous for us to do the same thing on interstates as we do on secondary roads, and vice versa."

For the rest of this story, watch Friday's WRAL News at 11 p.m.