We all know the rules of the road when it comes to speeding. White speed limit signs with black lettering are plastered along roadways letting drivers know how fast they’re allowed to go. And going ...

Since on-ramps are designed to help cars reach full speed to merge with traffic, it makes sense that ramp speed limits are at least as fast as those posted for that stretch of highway or freeway.

Yellow speed limit signs, such as this one on Blue Ridge Road in Raleigh, are called “advisory speed limit signs,” according to the Federal Highway Administration. They are posted for “a small portion ...