How are lane and shoulder widths determined?
The 3R analysis is the primary tool used to determine lane and shoulder widths, and horizontal and vertical curves. The purpose of a 3R analysis is to determine where and what type of safety improvements should be included in resurfacing, restoration, and rehabilitation (3R) projects. If an unusually high number of accidents are occurring within the project area, then safety improvements are evaluated. These improvements could increase the roadway width or improve the alignment. In some cases the improvements include roadway illumination. Under the 3R procedures, all roadway features are not required to be upgraded to “new construction” standards, consequently lowering the cost of improvements and reducing impacts to adjacent private property.
