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The Evolution of Urban Roadway Design Approaches


The approach and practice of urban roadway design in North America has evolved on
the basis of research and experiences for higher speed rural style highways that form
part of a national or regional transportation system. The various design guidelines that
have been developed over past decades evolved out of a need to develop efficient,
effective and safe highway systems. Early examples of such guidelines
(AASHO/AASHTO, CGRA/RTAC/TAC etc.) focused largely on the technical issues of
vehicular travel. This led to the use of functional classifications that dictated design
speed, design vehicle, access control, levels of service and related design
From the late 1970s onward, there has been a distinct shift in the approach taken
towards roadway design, particularly in increasingly more congested urban areas.
Since that time there has been considerable attention paid to a host of factors that had
up to that point had been given less attention by roadway designers. This included
issues such as noise, air quality, speeding, shortcutting, community severance, other
travel modes (transit, pedestrians, and cyclists) as well as urban design, public realm
and place-making considerations.
The language of urban road design in 2014 is now permeated by words and phrases
like “traffic calming”, “context sensitive design”, “multi-modal design”, “complete streets”,
“green roads”, “sustainable transportation” and “pedestrian oriented” design. The
general public is demanding much more of transportation engineers than they did in the
60s and 70s. This has led to increased complexity in the design process, its objectives
and the design parameters that form part of that process.
This paper describes the evolution in the urban roadway design process and the related
parameters. This evolution is described through a comparison of historical approaches
with more contemporary practices and attitudes. The paper highlights emergent
methodologies that reflect the changes from historical practice and outlines the
influences from other jurisdictions and other disciplines. 

Conference Paper Details

Session title:
Geometric Design - Learning from the Past
H. Shaheen
Geometric design