Design Flexibility Considerations for Built Urban Environments. Research Results Digest 337

摘要

Roadway designers rely on design standards (mandatory practice), guidelines (recommended practice, but not mandatory), and policies to develop a roadway facility that will be safe, address mobility concerns, accommodate the physical and social environment, and be financially feasible. Balancing these elements becomes a critical part of the design process and sometimes it may not be practical to strictly conform to existing guidelines or standards. To address potential conflicts, the roadway design may need to deviate from the prevailing guidelines and policies. The increased density of development and populations in built urban environments and the need for contextual designs to address community needs could result in a more frequent need for design exceptions or variances. An understanding of the impacts of such alternative designs on both the safety and the operational character of the roadway is essential. In large cities, limited right-of-way, human and natural environmental issues, pedestrian and bicyclist accommodation, and aesthetic concerns often require a more contextual design to be used than in non-built environments. It is therefore often required to develop unique solutions that may not conform to existing guidelines and require the use of design exceptions or variances.