A method was needed that can help NCDOT field engineers quickly and reliably evaluate the existing superelevation rate and radius for any curve against current AASHTO design standards which are adopted in the NCDOT Roadway Design Manual. Having a quick and reliable method will enable NCDOT to rapidly investigate any horizontal curve against current design standards and make recommendations for corrective action if needed.
A simple procedure was developed that can take several field measurements, including the superelevation rate, and convert them into the radius of the curve. These values can then be compared to design standards that are presented in charts for direct review in the field without the need for calculations or coming back to the office. This is an efficient field investigation of horizontal curves against current design standards. Another aspect of the investigation is a quick method to estimate whether or not SSD is provided through the curve."
