Content deleted Content added
→History: "dark yellow" ... are you even being serious. It's more red than yellow, and it's full brightness. There's a word for that... |
Rescuing 2 sources and tagging 0 as dead. #IABot (v2.0beta) |
||
Line 44:
===Traffic issues===
====Congestion causes and remedies====
Most [[traffic engineering (transportation)|traffic engineers]] consider the street hierarchy to be optimal, since it eliminates through traffic on all streets except arterials. However, some have contended that it actually exacerbates [[traffic congestion]], leading to [[air pollution]] and other undesirable outcomes.<ref>https://www.theatlantic.com/issues/2000/12/budiansky.htm</ref> An alternative to street hierarchy, [[Traditional Neighborhood Development]] (TND) networks, recommended by the Institute of Traffic Engineers, implies that a type of hierarchy is desirable nonetheless. It suggests that "While TND street networks do not follow the same rigid functional classification of conventional neighborhoods with local, collector, arterial and other streets, TND streets are hierarchical to facilitate necessary movements."<ref>{{cite web |url=http://www.cues.fau.edu/cnu/docs/Traditional_Neighborhood_Development_Street_Design_Guidelines-ITE.pdf |title=Archived copy |accessdate=2017-05-23 |deadurl=yes |archiveurl=https://web.archive.org/web/20110220174833/http://www.cues.fau.edu/cnu/docs/Traditional_Neighborhood_Development_Street_Design_Guidelines-ITE.pdf |archivedate=2011-02-20 |df= }} Whashington, DC</ref>
A more precise image of the prevalent thinking about structuring road networks can be found in the 2006 ITE/CNU recommended practice for the design of urban thoroughfares.<ref>http://www.ite.org/bookstore/RP036.pdf -Context Sensitive Solutions in Designing Major Urban Thoroughfares for Walkable Communities</ref> In it, the functional, traffic-engineering classifications of roads are replaced by three basic road types: boulevard, avenue and street with the addition of a second type of boulevard – the multi-way. These road types reflect familiar names and images of roads and also real conditions in an urban environment, where each type normally performs multiple functions but only up to a limit, a hierarchical limit. For example, a boulevard can function as a principal and minor arterial but not as a collector or local access street; an avenue, as principal/minor arterial and a collector but not as a street; while a street can serve as minor arterial, a collector and a local (access road) but not as a principal arterial. These exclusions of functional roles derive from the design intention to put an emphasis either on mobility or access; both cannot be accommodated concurrently in every case.
Line 59:
====Safety====
Transportation planners and traffic engineers have expressed concerns over the traffic safety drawbacks presented by the street hierarchy. Recent studies have found higher traffic fatality rates in outlying suburban areas than in central cities and inner suburbs with smaller blocks and more-connected street patterns.<ref>http://www.minority.unc.edu:9014/sph/minconf/2004/materials/ewing.etal.pdf</ref><ref>{{cite web |url=http://www.virginia.edu/topnews/releases2002/lucy-april-30-2002.html |title=Archived copy |accessdate=2006-09-03 |deadurl=yes |archiveurl=https://web.archive.org/web/20060903234004/http://www.virginia.edu/topnews/releases2002/lucy-april-30-2002.html |archivedate=2006-09-03 |df= }}</ref> While some of this disparity is the result of distance from emergency medical facilities (hospitals are usually not built in a newly developed suburban area until a fairly late stage in its development), it is clear that the higher speeds engendered by the street hierarchy increase the severity of accidents occurring along arterial roads.
An earlier study<ref>Eran Ben-Joseph, Livability and Safety of Suburban Street Patterns: A Comparative Study (Berkeley, CA: Institute of Urban and Regional Development, University of California, Working Paper 641, 1995)</ref> found significant differences in recorded accidents between residential neighbourhoods that were laid out on an undifferentiated grid and those that included culs-de-sac and crescents in a hierarchical structure. The frequency of accidents was significantly higher in the grid neighbourhoods.
| |||