The Development of Safety Evaluation Criteria for the Alignment Design Consistency Methods on Rural Highways

This thesis focused on the research of a method to evaluate and improve alignment design consistency in the respect of safety. The design consistency depends on the conformance between drivers expectancy and highway geometry, so that the evaluation criteria for consistency should efficiently represent drivers behavioral characteristics. Under the conditions, this research included a new evaluation criteria development and an analysis on how to change evaluation criteria according to roadway alignments, to evaluate safety. The newly developed evaluation criteria, spacing mean represented the drivers behavioral characteristics effectively on association area for a roadway segment alignment. Additionally the interrelationship with accident history data is also high. The existing operating speed evaluation criterion had the limit on the safety validation of roadway alignments association area because of lack of operating speed expectation method. However, new evaluation criteria model can supplement the limited existing criterion. The new evaluation criteria is intended for application by highway agencies to estimate the safety performance an existing or proposed roadway. The evaluation criteria model can be used to compare the anticipated safety performance of two or more geometric alternatives for a proposed highway improvement.