Evaluation and Modification of Sight Distance Criteria Used by TxDOT (0-1811-S)

Sight distance is an important consideration in roadway design, affecting many aspects of highway safety and operations. Ramp, interchange, and intersection designs are typically completed in tightly constrained spaces with many structural, earthwork, and roadway features present that may obstruct sight distance. These features are not easily moved; if consideration of sight distance constraints is not given early in the design process, designs may be compromised and a reduced level of safety may be encountered by the public on the completed roadway. After conducting a literature review of design criteria, three case studies of interchange ramps, and a thorough review of the TxDOT Design Division Operations and Procedures Manual, the authors recommended revisions for the manual. These revisions include material intended to clarify and extend the consideration of sight distance in roadway design.