Un outil d’aide à la décision pour l’urbanisme règlementaire Application au Plan Local d’Urbanisme (PLU) de Toulouse 1 * AVENUES – GSU ; EA 7284. University

Un outil d’aide à la décision pour Un outil d’aide à la décision pour l’urbanisme l’urbanisme règlementaire règlementaire

Application au Plan Local d’Urbanisme Application au Plan Local d’Urbanisme (PLU) de Toulouse(PLU) de Toulouse

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* AVENUES – GSU ; EA 7284. University of Technology of Compiègne – France** Toulouse Métropole – DGDUD – Direction Planification et Urbanisme – Toulouse - France

Journée du 26 juin 2013 – Lamsade Université Paris Dauphine

Aurélie PREVOST*, Nathalie MOLINES* , Jean BANDET * *

A NEW TOOL TO ASSESS THE EFFECTS OF THE A NEW TOOL TO ASSESS THE EFFECTS OF THE REGULATIONS ON URBAN FORMS : AIMS AND REGULATIONS ON URBAN FORMS : AIMS AND OBJECTIVES OBJECTIVES PhD research, collaboration with the city of Toulouse (CIFRE PhD)In the regulatory planning department.

Objective of the research : to create an aiding decision tool for regulatory planners, that allow them to anticipate and understand the impacts of urban regulations that can be complexAt the scale of the city, because the PhD focuses on local plans (PLU) and its regulations

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DEFINITION AND CONTENT OF THE FRENCH LOCAL DEFINITION AND CONTENT OF THE FRENCH LOCAL PLANS (PLU) PLANS (PLU)

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The PLU (local plan)

Content

1. Territorial diagnosis

2. Contains a PADD = territorial management priorities with a crosscutting approach (city council project for the development of the city)

3. Traduction of the PADD’s guideline into a statutory zoning and a set of regulations for each zone - Traditionaly dealing with: land occupation, building shape and density, layout of the plot, and amenities (public facilities) – 14 statutory articles ! (16 with Grenelle law)

+ (if required) : environmental assessment chapters : ex-ante and ex-post assessment of the plan with indicators

Planning system, local plan

Aims/objectives of the research

approach and developments

Ex-post assessment using

Electre tri

Ex-ante assessment

Conclusion, perspectives

AIMS AND OBJECTIVES OF THE RESEARCHAIMS AND OBJECTIVES OF THE RESEARCH Environmental assessment process for some local plans with an ex-ante and ex-post evaluation = indicators But …. Those indicators seem not to be adapted to assess the impacts of the regulations chosen for the different zones :

they seem to be more useful for ecological public managment of the city than urban and regulatory managment …. Due to the complexity of the relations between the regulations and the « urban environment » as a system

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Electre tri

Ex-ante assessment


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As an aiding tool for statutory planners, the research tries to overcome that gap, focusing on 3 traditionnal regulatory themes contained in the plans : building shape and density ; layout of the plot and amenities. They are part of the definition of the « urban intensity », and participate to some aspects of sustainable planning

AIMS AND OBJECTIVES OF THE RESEARCHAIMS AND OBJECTIVES OF THE RESEARCH





Electre tri

Ex-ante assessment


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Com

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1. Definition of the

corpus of indicators

2. Synthesis and

agregation

Principal component analysis

Principal component analysis

Multicriteria analysisELECTRE TRI

Multicriteria analysisELECTRE TRI

Complementary tools : Analysis of the building fabric thanks to multivariate analysis

(statistical) ACP et CAH

Electre tri will allow us to rank the 5 zones, using « profiles » that

separate categories of assessment. The profiles are based on an

analysis of the whole city





Electre tri

Ex-ante assessment


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First aim : create a corpus of indicators which reflects the evolutions and the current morphological situation of each zone of the plan3 traditional regulatory issues : Density : 5 indicatorsUnbuilt areas : 3 indicatorsAmenities : 5 indicators





Electre tri

Ex-ante assessment


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EXAMPLE OF AN « AMENITY» CRITERIAEXAMPLE OF AN « AMENITY» CRITERIAEach zone of the plan contains a lot of geographical objects called « units of zones » We calculate the surfacic rate of each unit of zone, covered by the amenity ; later we can assess the territory at this scale with Electre tri





Electre tri

Ex-ante assessment


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AGREGATION : EX-POST EVALUATION OF THE AGREGATION : EX-POST EVALUATION OF THE « AMENITIES »USING ELECTRE TRI« AMENITIES »USING ELECTRE TRIPlanning system,

local planAims/objectives of

the researchapproach and developments


Electre tri

Ex-ante assessment


The ex-post agregation is made on the 3 traditional regulatory themes contained in the plans : building shape and density ; layout of the plot and amenities.

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AGREGATION : EX-POST EVALUATION OF THE AGREGATION : EX-POST EVALUATION OF THE « AMENITIES »USING ELECTRE TRI« AMENITIES »USING ELECTRE TRIFor amenities :the goal is to assess the unit of zones, regarding the amenities contained. Benefits for planners : -where are the lacks in terms of public facilities ? -in wich zone could we prioritize public action to develop amenities ?-is the number of amenities consistent with the main « function » of the zone (industrial, housing, services) -is the number of amenities consistent with the built density of the zone allowed by the local plan?





Electre tri

Ex-ante assessment


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5 indicators -Surfacic rate of zone covered by the buffer around public transportation stations-Surfacic rate of zone covered by daily-life shops spots (shops micro-areas)- surfacic rate of zone covered by the buffer around daily-life shops places-Surfacic rate of zone covered by public green areas or green network- Surfacic rate of zone covered by the buffer around a school or a nursery

AGREGATION : EX-POST EVALUATION OF THE AGREGATION : EX-POST EVALUATION OF THE « AMENITIES »USING ELECTRE TRI« AMENITIES »USING ELECTRE TRIPlanning system,

local planAims/objectives of

the researchapproach and developments


Electre tri

Ex-ante assessment


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AGREGATION : EX-POST EVALUATION OF THE AGREGATION : EX-POST EVALUATION OF THE « AMENITIES »USING ELECTRE TRI« AMENITIES »USING ELECTRE TRIDefinition of the « profiles » :2 methods are used for the definition of the « profiles » :1. First one : Based on arbitrary thresholds : - profile 3 : 25% of the unit is covered- profile 2 : 50% is covered- profile 1 : 75% is covered

2. Second one : based on the real distribution of the datas, for the whole cityUsing a K-mean discretisation on the results of each indicators calculated for the unit of the zones for the hole city





Electre tri

Ex-ante assessment


Profile 3

Profile 2

Profile 1

Result of K-means discretization of the distribution for the Surfacic rate of each unit of zone covered by public transportation network : the red points represent the profiles

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AGREGATION : EX-POST EVALUATION OF THE AGREGATION : EX-POST EVALUATION OF THE « AMENITIES »USING ELECTRE TRI« AMENITIES »USING ELECTRE TRIParameters :- Indifference and preference thresholds are defined as 5 and 10 % - No veto is defined - Weigh is the same on every criteria- the cut threshold (λ ), for the reference tests is chosen equal to 0,76 Robustness analysis is done later on every parameter, and profilesWe only give the results of the pessimistic procedure of Electre tri





Electre tri

Ex-ante assessment


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5 indicators of amenities ; profiles defined by 25 -50 -75%Cut threshold stable on [0,7 ;0,8]

5 indicators of amenities ; profiles defined using K-means discretization. Cut threshold stable on [0,7 ;0,8]

Best results : lots of amenities

Worst results

Numerous incomparabilities of the action = the unit of zone is assigned in the worst class in pessimistic procedure, and on the 2 best ones in optimistic procedure

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AGREGATION : EX-POST EVALUATION OF THE « AMENITIES » AGREGATION : EX-POST EVALUATION OF THE « AMENITIES » USING ELECTRE TRIUSING ELECTRE TRIZone Description of the zone Class 4 Class 3 Class 2 Class 1UA1 Historical center 100% idemUA2 Center of the city, near historical center 100% idemUA3 close to the center, inner suburbs 100% idemUA4 8 « inner city villages », in the periphery 73% idem 9% -9 9% +9 9% idemUB1 located further than UA3, mixity of building shape and functiunal diversity 45% -2 11% -5 14% +6 30% idemUB2 areas of collective blocks 66% -4 13% +2 7% +4 15% idemUC1 mostly individual housing, separated or adjoining houses 45% -6,5 16% idem 10% +6,5 29% idemUC2 separated individual housing 14% idem 5% idem 5% idem 77% idemUE1 Economic activities 12% -6 10% +2 16% +8 61% -4UE2 Economic activities, mostly tertiary 8% -2 18% +3 25% +10 50% -10UE3 Aeraunautic activities and airports 100% idemUP Areas dedicated to the main public facilities: hospitals, universities… 61% -6 6% +4 11% +5 22% -4

Center of the city

K-means methods for profile is sensibly more strict than the arbitrary method





Electre tri

Ex-ante assessment


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Toulouse’s city council prescribed the creation of a new local plan in march 2011. One of the new objective for that local plan is to create a « urbanism - transportation network – public facilities consistency »

create units of zones and rules (maximal heigh of building allowed) that give more density close to the transportation network first, but also public facilities on the opposite, if some areas dont respond well to that objective, it implies to change rules (heigh of buildings) and allow less density on those areas





Electre tri

Ex-ante assessment


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The method used by planners to modify the plan :1. To Create a cartography of the current statutory zoning with some public facilities and the buffer aroud the public transportation network1. To define, based on their experience and knowlegde of the territory, the new units of zones, that are planned to allow more density, (or less)

« Expert and experience based method »





Electre tri

Ex-ante assessment


The purpose of implementing the indicators created and later, ELECTRE TRI is to validate the choices previously made by planners, before final approbation

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Electre tri

Ex-ante assessment


Method : 1. We calculate the 5 indicators on the units intially defined by planners2. We use ELECTRE TRI to assess the global « rate of amenities » of each unit. If the result is good, we can validate more density.Parameters : - profiles defined by 25% - 50% - 75% of coverage-Indifference and preference thresholds : 5 % and 10 %- veto on the indicator of public transportation network : v= 15% : reflects the fact that it is the first criteria to take into account to allow more density- weigh similar on every indicator - cut threshold (λ) equal to 0,76 Every parameter is tested later

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Results : Globally, where the planners decided to allow more density, (inside the buffer around transportation stations), the result given by multicriteria analysis is also goodWhere they decided to lower future density of buildings, mostly out of the buffer, the result given by Electre tri is not the best ; a lot of incomparabilities are calculated. Those are assigned in the worst classes with the pessimistic procedure.For the exceptions : after discussion with the planners, some other planning issues made them decide other way :- create a urban project with mixed urban forms (Eco district, morphological transitions…)- limitate the density because the capacity of city managment networks is not sufficient yet - limitate density because another project nearby must be finished in priority

An ex-post analysis has been made on the 3 traditional issues of regulatory planning : density, unbuilt private areas, amenities. Ex-post analysis with ELECTRE TRI: Aiding tool for planners, help them to understand the impacts of regulations before modifying the rules Ex-ante analysis with ELECTRE TRI : allow planners to justify and validate choicesBut… those methods must be completed by discussions with experts, since knowlegde cannot be replaced by models due to complexity

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Electre tri

Ex-ante assessment


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Thank you for your attention

Documents

Un outil d’aide à la décision pour l’urbanisme règlementaire Application au Plan Local d’Urbanisme (PLU) de Toulouse 1 * AVENUES – GSU ; EA 7284. University