01131295

Monograph

http://www.trb.org/Publications/Blurbs/161959.aspx

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. The objective of this report is, therefore, to (1) understand why such departures from the guidelines may be needed or desired, (2) identify processes that successfully manage such design procedures, and (3) determine means that could assist designers to streamline this process and provide a timely procedure for addressing design exceptions or variances. These three objectives were addressed through a survey of design and variance procedures of local transportation agencies for large cities and state departments of transportation.

English

29p

2009-6

NCHRP Research Results Digest

Print

Figures (8) ; Photos (4) ; References (32) ; Tables (1)

Built environment; Context sensitive design; Design standards; Guidelines; Highway design; Large cities; Local government agencies; Policy; State departments of transportation; Surveys

Design exceptions; Variances

Design; Highways; I20: Design and Planning of Transport Infrastructure

TRIS, TRB, ATRI

Jun 26 2009 9:04AM