An important objective in horizontal curve signing is having a uniform and consistent display of advisory speed on curves of similar geometry, character (e.g., sight distance, intersection presence, etc.), and road surface condition. As stated in the , “uniformity of the meaning of traffic control devices is vital to their effectiveness” (Section 1A.02). It further describes the benefits of uniformity in the following statement.

“Uniformity of devices simplifies the task of the road user because it aids in recognition and understanding, thereby reducing perception/reaction time. Uniformity means treating similar situations in a similar way.” (Section 1A.06).

The uniform application of a traffic control device allows drivers to develop an expectation that leads to the correct interpretation of device message. In this manner, a uniformly applied advisory speed will be more likely to be understood and respected by drivers.

Research indicates that the historically inconsistent use of curve warning signs, especially those with an advisory speed plaque, may have lessened the average motorist’s respect for the message the signs convey. On familiar highways, drivers have come to learn that they can comfortably exceed the advisory speed for most curves. The concern is that these drivers may occasionally travel on roadways that are less familiar to them and where the advisory speed is posted at the maximum safe speed. These drivers may find themselves traveling too fast for conditions and experience uncomfortable side forces. In extreme cases, they may lose control of the vehicle and slide off the roadway.