DESIGN EXCEPTIONS AND CONTEXT-SENSITIVE DESIGN

This paper describes how highway and street construction and improvement projects are designed to conform to agency-adopted geometric criteria. In some situations, achieving conformance with all design criteria is not practical or reasonable. Because design features that do not meet criteria may affect the safety and operational efficiency of the facility, a decision to depart from criteria should be deliberative, documented and approved by an authorized official. A "design exception" is the process and associated documentation of creating or perpetuating a geometric feature that does not meet applicable criteria. All state transportation agencies prepare design exceptions; however, the volume of design exceptions, project conditions requiring their preparation, and approval roles vary substantially among states. This paper provides information from a recently completed National Cooperative Highway Research Program (NCHRP) Synthesis on Design Exception Practices. Specifically, the paper briefly addresses the following: (1) the relationship between design exceptions and context-sensitive design; (2) the conditions requiring preparation of a design exception; and (3) design exception practices among State Transportation Agencies. A survey completed by 46 State Transportation Agency (STA) managers and a review of the written design exception procedures from 30 STAs provided the majority of the information reported in the synthesis.