Editing Grid plan (section)

===Late 19th century to the present===
[[File:BCN01.JPG|thumb|[[Barcelona]]]]
[[File:Original design of Barcelona's city blocks.svg|right|thumb|The city blocks and streets of Barcelona as conceived by [[Ildefons Cerdà]]. The blocks include wide open spaces that continue across the street to adjacent blocks.]]
[[Ildefons Cerdà]], a Spanish civil engineer, defined a concept of urban planning, based on the grid, that he applied to the [[Eixample]] of [[Barcelona]]. The Eixample grid introduced innovative design elements which were exceptional at the time and even unique among subsequent grid plans:
* a very large block measuring {{convert|113|by|113|m|ft|abbr=on}}, far larger than the old city blocks and larger than any Roman, Greek blocks and their mutations (see drawing below);
* a {{convert|20|m|ft|abbr=on}} road width (right of way) compared with mostly 3 m in the old city;
* square blocks with truncated corners; and
* major roads, perpendicular and diagonal, measuring {{convert|50|m|ft|abbr=on}} in width.
Cerda formulated these innovations in response to changing functional needs. As cities grew larger, through traffic, travel distance, noise, and pollution from carts became significant issues. Larger blocks with major perpendicular roads enables the creation of a quiet interior open space (60 m by 60 m) and allow ample sunlight and ventilation to its perimeter buildings; the rectilinear geometry, the wide streets and boulevards to sustain high mobility and the truncated corners to facilitate turning of carts and coaches and particularly vehicles on fixed rails.<ref>[https://whc.unesco.org/document/6806 'activity-38-1.pdf' World Heritage Papers 5: Identification and Documentation of Modern Heritage] Published in 2003 by the UNESCO World Heritage Centre, p36 and multiple further pps, Including footnote: "See Ildefonso Cerdá, Teoría general de la urbanización y aplicación de sus principios y doctrina a la reforma y ensanche de Barcelona, Madrid, 1867." Accessed 17 May 2017</ref> As buildings became taller, the new design also permitted a more natural sense of scale to the buildings from the street and reduced wind speeds.<ref name=":0">{{Cite AV media |url=https://www.youtube.com/watch?app=desktop&v=Lgio_ygetbo. |title=Why Don't Cities Use Hexagon Blocks? |date=2023-10-08 |last=City Beautiful |access-date=2025-04-03 |via=YouTube}}</ref><ref>{{Cite AV media |url=https://www.youtube.com/watch?v=qQ7MP2e7Bqk |title=U.S. Zoning, Explained |date=2023-02-28 |last=City Beautiful |access-date=2025-04-03 |via=YouTube}}</ref>

In the early 1900s, urban planners such as New York architect [[Charles Rollinson Lamb|Charles Lamb]], who was one of the first to sketch out a city plan with a [https://hub.paper-checker.com/blog/hexagonal-cities-revolutionizing-urban-design-through-geometry/#:~:text=Hexagonal%20cities%20are%20urban%20layouts,network%20of%20streets%20and%20spaces. hexagonal grid], and Rudolf Muller, Austrian architect who iterated upon Lamb's hexagonal grid system, demonstrated their application and value to city grids. During the 1920s, [https://www.biographi.ca/en/bio/cauchon_noulan_16F.html Noulan Cauchon], a Canadian planner and engineer, further refined and optimized the hexagonal model—even showing how it can be integrated into existing cities.<ref name=":0" /> With growing concerns over vehicle flow, this model provided a reduction in collision points; from 16 to just 3 by reducing the 4-way intersection of a traditional orthogonal grid, to a 3-way intersection that allows for better sightline with its obtuse 120° angle.<ref name=":1">{{Cite journal |last1=Ben-Joseph |first1=Eran |last2=Gordon |first2=David |date=October 2000 |title=Hexagonal Planning in Theory and Practice |url=https://doi.org/10.1080/713683965 |journal=Journal of Urban Design |volume=5 |issue=3 |pages=237–265 |doi=10.1080/713683965 |issn=1357-4809}}</ref><ref name=":0" /> However, [https://parks.canada.ca/culture/designation/personnage-person/thomas-adams Thomas Adams] who was "pivotal in making urban planning a separate profession and in codifying residential design practice" <ref name=":1" /> preferred square grids and suburban cul-de-sacs. Adam's rebutted Cauchon's work in his co-authored [[Harvard University|Harvard]] book: ''The Design of Residential Areas: Basic Considerations, Principles, and Methods'' (1934), modifying Cauchon's drawings to disfavour hexagonal grids, despite them being the most efficient grid model.<ref name=":0" /> This publishment received widespread attention, and led to the adoption of square grids in the downtown areas of most large American colonial cities. 

These areas represent the original land dimensions of the founded city, generally around one square mile. Some cities expanded the grid further out from the centre, but maps also show that, in general, as the distance from the centre increases, a variety of patterns emerge in no particular discernible order. In juxtaposition to the grid, they appear random. These new patterns have been systematically classified and their design characteristics measured.<ref>{{cite journal | last1 = Southworth | first1 = Michael | last2 = Owens | first2 = Peter | name-list-style=amp | year = 1993 | title = The Evolving Metropolis: Studies of Community, Neighbourhood, and Street Form at the Urban Edge | journal =   Journal of the American Planning Association| volume = 59 | issue = 3| pages = 271–288 | doi=10.1080/01944369308975880}}</ref>

In the United States, the grid system was widely used in most major cities and their [[suburb]]s until the 1960s. However, during the 1920s, the rapid adoption of the [[automobile]] caused a panic among [[urban planning|urban planners]], who, based on observation, claimed that speeding cars would eventually kill tens of thousands of small children per year. Apparently, at this early stage of the car's entry into the grid, the streets of major cities worldwide were the scene of virtual "slaughter" as the fatality rate in proportion to population was more than double the current rate.<ref>{{cite web|url=http://www.factbook.net/EGRF_Regional_analyses_HMCs.htm |title=Estimating global road fatalities – Regional Analyses – Highly Motorised Countries |access-date=2014-12-12 |url-status=usurped |archive-url=https://web.archive.org/web/20100704165123/http://www.factbook.net/EGRF_Regional_analyses_HMCs.htm |archive-date=2010-07-04 }}</ref><ref>[https://www.unece.org/fileadmin/DAM/trans/main/wp6/pdfdocs/RAS_2007.pdf Statistics of Road Traffic Accidents in Europe and North America Published: January 2007 or Published: April 2007] Accessed 17 May 2017</ref> In 2009, after several decades of road safety improvements and a continuous decline in fatalities, an estimated 33,963 people died in motor vehicle traffic crashes and, according to the National Highway Traffic Safety Administration, "Motor vehicle crashes are the leading cause of death for children from 3 to 14 years old."<ref>[http://www-nrd.nhtsa.dot.gov/Pubs/811291.PDF Early Estimate of Motor Vehicle Traffic Fatalities in 2009 at crashstats.nhtsa.dot.gov] Accessed 16 May 2017</ref> Planners, therefore, called for an inwardly focused "[[City block#Superblock|superblock]]" arrangement that minimized through automobile traffic and discouraged cars from traveling on anything but [[arterial road]]s; traffic generators, such as apartment complexes and shops, would be restricted to the edges of the superblock, along the arterial. This paradigm prevailed between about 1930 and 1960, especially in [[Los Angeles, California|Los Angeles]], where notable examples include [[Leimert Park, Los Angeles, California|Leimert Park]] (an early example) and [[Panorama City, Los Angeles, California|Panorama City]] (a late-period one).

[[File:Mittelholzer-ouagadougou.jpg|thumb|left|[[Ouagadougou]] ([[Burkina Faso]], ex [[Republic of Upper Volta|Upper Volta]], [[Africa]]), 1930]]A prominent 20th century urbanist, [[Lewis Mumford]], severely criticized some of the grid's characteristics: "With a T-square and a triangle, finally, the municipal engineer could, without the slightest training as either an architect or a sociologist, 'plan' a metropolis, with its standard lots, its standard blocks, its standard street widths, in short, with its standardized comparable, and replaceable parts. The new gridiron plans were spectacular in their inefficiency and waste. By usually failing to discriminate sufficiently between main arteries and residential streets, the first were not made wide enough while the second were usually too wide for purely neighborhood functions... as for its contribution to the permanent social functions of the city, the anonymous gridiron plan proved empty."<ref>[[Lewis Mumford|Mumford, Lewis]] (1961) ''The City in History: Its Origins, Its Transformation, and Its Prospects''. New York: Harcourt Brace Jovanovich. p.425.</ref>

In the 1960s, [[Traffic engineering (transportation)|traffic engineers]] and urban planners abandoned the grid virtually wholesale in favor of a "[[street hierarchy]]". This is a thoroughly "asymmetric" street arrangement in which a residential subdivision—often surrounded by a [[Noise barrier|noise wall]] or a [[gated community|security gate]]—is completely separated from the road network except for one or two connections to arterial roads. In a way, this is a return to [[medieval]] styles: as noted in [[Spiro Kostof]]'s seminal history of [[urban design]], ''The City Shaped'', there is a strong resemblance between the street arrangements of modern American suburbs and those of medieval [[Arab]] and [[Moorish]] cities. In each case, the community unit at hand—the clan or extended family in the [[Muslim]] world, the economically homogeneous [[Subdivision (land)|subdivision]] in modern suburbia—isolates itself from the larger urban scene by using dead ends and ''[[cul-de-sac|culs-de-sac]]''.

[[File:Milton Keynes Sector.jpg|right|thumb|A one km<sup>2</sup> sector in [[Milton Keynes]] framed by major roads in a grid configuration. The road network within the sector uses cul-de-sac streets complemented by bike and foot paths which connect the entire sector and beyond.]]

====Milton Keynes====
{{Main|Milton Keynes grid road system}}
One famous grid system is in the British new town of [[Milton Keynes]]. In this planned city, which began construction in 1967, a system of ten "horizontal" (roughly east–west) and eleven "vertical" (roughly north–south) roads was used, with [[roundabout]]s at each intersection. The horizontal roads were all given names ending in 'way' and H numbers (for 'horizontal', e.g., H3 Monks Way). The vertical roads were given names ending in 'street' and V numbers (for 'vertical', e.g., [[V6 Grafton Street]]). Each grid road was spaced roughly one kilometre along from the next, forming squares of approximately one square kilometre. Each square and each roundabout was given its own name. The system provided very easy transport within the city, although it confused visitors who were unfamiliar with the system. The grid squares thus formed are far larger than the city blocks described earlier, and the road layouts within the grid squares are generally 'organic' in form – matching the street hierarchy model described above.