The Straight-line Diagrammer, a web-based application to produce Straight-line Diagrams (SLDs) automatically, was developed in this project to replace the old application (AutoSLD), which has out-dated structure and limited capabilities. The new application provides enhancements beyond replicating the functions of the old stand-alone application. The enhancements include: to create a direct connection to the Florida Department of Transportation (FDOT) Roadway Characteristics Inventory (RCI) database; to modify SLDs according to the changes in the RCI database; to provide a user friendly interface to reduce the workload and learning curve; to present customizable outputs of SLDs; to offer savable generation schemes; to re-generate SLDs easily; to integrate online help information; and to incorporate additional RCI data.