Context Classification: A New Approach for Improving Highway Design

The Functional Classification System (FCS) in the US has been the driving force in developing and designing roadway projects. FCS was originally developed as a basis for communication between designers and planners but since then, it has expanded and is used throughout the entire project development process and more importantly serves as a surrogate for design inputs (e.g., design speed). However, the FCS has a narrow focus, and it is auto centric. The limited contextual definitions (urban and rural) do not provide the dynamic range of design elements and guidance needed to balance other competing project needs and it lacks the resolution needed to develop context-sensitive designs. NCHRP Report 855 introduced an expanded context classification system that supports more integrative and context-adapted roadway designs. This system was adopted in the 7^th Edition of the Policy of Geometric Design for Highways and Streets (Green Book). Transitioning from functional classification to context classification entails a major shift in design practices. Context sets expectations for each setting and informs the entire project development process. This paper presents an update of the Green Book's context classifications and introduces the concept of Transportation Expectations, which are fundamental concepts that define how users expect to move in each context. Examples of applications are presented that explore these concepts and discuss how they could facilitate multimodal roadway designs — the focal point of upcoming Green Book 8^th Edition.