An innovative methodologicalapproach for the analysis of the effects of urban interventions on property prices

The evaluation of the effects that an urban intervention generates on the area in which it is realized, and more generally on the city-system, plays a central role in the definition of its effectiveness, as it measures the effects that may derive from its implementation in terms of improving the quality level of the natural and built environment. The present research intends to propose and test a methodological and operational approach to evaluate, with quantitative indicators, the effects that an urban redevelopment initiative can have on property prices. In particular, the aim of the work concerns the development of a procedural protocol articulated into clear and replicable phases, in order to support the analysis of the urban transformation effects. The protocol is applied to four redevelopment projects currently in progress, located in four municipal trade areas in the city of Bari (Southern Italy). For each urban area, a sample of two hundred residential properties sold in the period 2017-2019 has been collected. The implementation of a genetic algorithm has allowed the definition of the econometric price function, able of identifying the set of variables - intrinsic and extrinsic – which, in each of the four intervention areas, contributes to the formation of property prices in the “ante-project” situation. The analysis of the effects of urban redevelopment in terms of variation of the urban quality has been carried out. Through an exogenous approach based on the inter-view of experts and community individuals, the values of the factors related to the urban quality following the implementation of the projects have been determined again (“post-project” situation). By inserting the new values into the econometric price functions already found, the market values of the post-project situation have been estimated. The comparison between ex ante and ex post market values shows the increase in property prices following the redevelopment initiative and allows to quantify it, confirming the full consistency with the expected empirical trends. alternative progettuali, la definizione di una lista di priorità temporale sulla base degli impatti che ciascuna ipotesi progettuale genera sul contesto di riferimento. Questo strumento, da codificare in un apposito protocollo procedurale strutturato in fasi dai contenuti chiari e ripercorribili, potrà essere impiegato Pubbliche Amministrazioni

The evaluation of the effects that an urban intervention generates on the area in which it is realized, and more generally on the city-system, plays a central role in the definition of its effectiveness, as it measures the effects that may derive from its implementation in terms of improving the quality level of the natural and built environment. The present research intends to propose and test a methodological and operational approach to evaluate, with quantitative indicators, the effects that an urban redevelopment initiative can have on property prices. In particular, the aim of the work concerns the development of a procedural protocol articulated into clear and replicable phases, in order to support the analysis of the urban transformation effects. The protocol is applied to four redevelopment projects currently in progress, located in four municipal trade areas in the city of Bari (Southern Italy). For each urban area, a sample of two hundred residential properties sold in the period 2017-2019 has been collected. The implementation of a genetic algorithm has allowed the definition of the econometric price function, able of identifying the set of variables -intrinsic and extrinsic -which, in each of the four intervention areas, contributes to the formation of property prices in the "ante-project" situation. The analysis of the effects of urban redevelopment in terms of variation of the urban quality has been carried out. Through an exogenous approach based on the interview of experts and community individuals, the values of the factors related to the urban quality following the implementation of the projects have been determined again ("post-project" situation). By inserting the new values into the econometric price functions already found, the market values of the post-project situation have been estimated. The comparison between ex ante and ex post market values shows the increase in property prices following the redevelopment initiative and allows to quantify it, confirming the full consistency with the expected empirical trends.

INTRODUCTION
Urban area redevelopment policies are among the most important issues in the debate on the recovery from the economic crisis triggered in 2007 by the American subprime and still in progress.
In this sense, the degraded or abandoned areas, currently considered as urban voids and places of social unrest concentration, are starting to be seen as an opportunity for the economic cities development, as possible containers of functions in accordance with the needs and the community demands.
The redevelopment processes of more or less extensive portions of the territory or buildings, operate on the settlements system and produce effects on the entire city, determining economic and social externalities that are reflected in its image (Agnoletti et al., 2014). The quantification of these impacts plays an important role to guide the decision-making processes of public and private investors.
In the recent years, the need to evaluate and measurein social, economic and environmental terms -the effects generated by territorial transformation inter ventions has been occurred with increasing intensity (Rosato, 2017).
The notion of "urban quality", intended as a goal to be pursued in the context of settlement processes and territorial dynamics, is strongly debated by urban planners, architects, economists, environmentalists, anthropologists and sociologists. The "quality" of an area is unavoidably linked to the community quality of life, as it influences the well-being of citizens who live it, in terms of health and psychological tranquility. The relationship between the quality level of the urban environment and the social, physical, mental and economic well-being of the inhabitants (Ludlow, 2009) demonstrates the importance of enhancing public spaces, often characterized by degradation conditions or in an abandonment state, through strategic actions aimed at achieving a high quality standard.
The issue of disposal and functional reconversion of degraded areas and abandoned existing property assets has been widely dealt with in the reference literature and in the urban planning practice (Adair et al., 2000;Kort et al., 2011;Bottero et al., 2019;Morano et al., 2020). These assets have a fundamental role in: i) redefining the structure of a wider territorial system, ii) increasing the quality of the built environment, iii) growing the competitiveness of the city, iv) stimulating investments, v) i mproving and enriching the urban offer.
In the practice, the selection of the projects of an investment program, when it is not guided by political reasons or by emergencies related to the funding deadlines, is performed by evaluation tools that allow to verify the feasibility of the intervention from the point of view of all the subjects involved in the initiative and to better balance the interests of the parties. The financial analysis (e.g. Cost-Revenue Analysis), carried out exclusively from the point of view of the private entity (operation investor), concerns the verification of the convenience of the project "itself", i.e. its ability to repay the debt capital and to generate a profit for the entrepreneur (Kishore, 1996;Helfer t et al., 2001;Herbohn et al., 2002;French et al., 2005). Economic analyis (e.g. Cost-Benefit Analysis) extends the point of view of the assessment to the community, and compares the effects generated by the implementation of the intervention in terms of positive and negative effects (Lichfield, 1962;Marglin, 1963;Sassone et al., 1978;Layard, 1994;Boice, 1999;Brzozowska, 2007;Gabrielli et al., 2016). Given the spread difficulty of translating the economic effects on the territory into monetary terms, a growing interest in multi-criteria techniques, which allow to take into account the multidimensional nature of urban plans and projects assessments and to simultaneously pursue multiple objectives, by defining a compromise solution between the different economic, social and environmental issues, should be highlighted (Rosato, 1998;Beinat et al., 1998;Figueira et al, 2005;Munda, 2008;Nijkamp et al., 2013;Farinelli et al., 2016;Guarini et al., 2017;Guarini et al., 2018;Fregonara et al., 2019).

AIMS
The present research concerns the framework outlined and aims at the systematic analysis of the effects of urban interventions on property prices.
The aim relates the development of a methodological approach by which it is possible to evaluate, in the ex ante assessment phase and in quantitative terms, the effects that an urban intervention could generate on property prices. In particular, the study focuses on two questions: • the first concerns the notion of "urban quality"; • the second relates to the relationship between recovery projects, urban quality and property prices.
Specifically, the research intends to define and test i) an innovative model of urban quality assessment, ii) a methodological-operational approach that allows the evaluation of the effects generated by urban interventions on property prices.
The methodological-operational approach developed intends to be an original tool to support the decisionmaking processes of urban planning, the redevelopment of property assets and/or the functional reconversion of An innovative methodological approach for the analysis of the effects of urban interventions on property prices collective public spaces. The approach allows the assessment of the intervention effects on urban quality and on property prices and, in the presence of different project solutions, the definition of a list of temporal priorities based on the impacts that each project solution generates on the reference local context. The tool, to be encoded in a specific procedural protocol structured in stages with clear and replicable contents, can be used by Public Administrations and/or, in the case of publicprivate partnership, by private investors, in order to identify urban portions on which higher convenience to intervene is defined.
The paper is organized as follows. In Section 3 the notion of "urban quality" is investigated: after a brief overview of the main aspects that characterize the concept, the model that is proposed for assessing the urban space quality is illustrated. In Section 4 a procedural protocol divided into phases, to be implemented for the evaluation of the effects of urban interventions on property prices, is explained. In Section 5 the protocol is applied to a case study relating to the city of Bari: the urban interventions are specified and the variables of the model are outlined; the econometric technique used to define the function of the price is illustrated. Furthermore, the technique is implemented and the results obtained in the "anteproject" situation are shown; the analysis of the effects in the "post-project" situation is developed through i) the quantification of the variation of the urban quality level following the projects implementation, ii) the determination of the new property prices, iii) the comparison of the estimated prices in the "ante-project" and "post-project" situations; finally, the results obtained in terms of the initiatives effects on property prices are summarized. Finally, in Section 6 the conclusions of the work and the future perspectives of the research are discussed.

THE QUALITY OF URBAN SPACE
The relationship between man, natural environment and man-made one, is complex. In the social sciences, numerous studies have dealt with the issue of individual and collective well-being, not only in terms of economic wealth, but also of quality of life ones. In this regard, the growing interest in the urban economy for this question derives from the influence that the quality of life has on the increase and competitiveness of cities.
The urban quality notion includes an articulated characterization that reflects the nature of a complex system such as the city.
"Quality" is a gradual relative value, it varies according to the users, the places and their different and specific uses, but, above all, it changes with the times, culture, customs and tastes. It does not constitute a feature whose presence can be verified, as it does not show itself in absolute and tangible terms. The judgment on the quality of a place is expressed by the users of this area and is connected to the cultural, social and economic aspects of the reference population, their history and identity. There is no univocal and generally valid criterion able to measure the urban quality, as the evaluation of the place quality, as well as the well-being or quality of life, are strongly linked to individual perceptions.
The urban environment quality does not derive exclusively from the compliance with the forecasts of urban planning tools, especially if these are not supported by a planning phase able to guarantee the integration of all the population needs. Moreover, it does not derive from merely compliance with urban planning standards, since it is not enough to modify the quantitative relationships among the functions to automatically assurance their use by all inhabitants. Furthermore, the presence of services in a territorial system is not enough to ensure a high level of urban quality, because the correct proportionality, the balanced distribution and the accessibility of services must also be guaranteed. In the same way, it would be reductive to identify urban quality only with the "good architecture" of buildings, because it loses value if it does not refer to a relationship with its intended use and with the context in which it is included.
The question of urban quality has now a high relevance in the context of urban interventions planning, constituting a fundamental objective in the territory governance aimed at social development and economic growth of cities.

The urban quality indicators
In the last years, different researches have attempted to explain the urban quality multidimensional nature, and to quantify it for empirical research purposes. These studies are based on the heuristic assumption according to which the social and physical environment influences the users well-being, generating a sense of satisfaction (or dissatisfaction) with that space. This question is widely dealt with in the psychological disciplines context. On the other hand, Economists focus mainly on the physiopsychological relationship, in order to investigate the impact of it on the perception of the different urban areas factors and on the behavior of each subject (Lambiri et al., 2007). For example, Rogerson (1999) has analyzed the link between the quality of life and the settlement choices made by companies and individuals, highlighting how the life quality level can be used to promote a location to attract potential investors. Similarly, Hall (1995) has identified quality factors that could contribute to improve urban development.
In Shin et al. (2003) the two dimensions -objective and subjective -of the life quality have been considered as different identities. The first refers to manifest behavior and conditions on observable factors, such as the journal valori e valutazioni No. 26 -2020 economic wealth of a city, the health of its inhabitants, etc., assessed on the basis of the frequency with which the phenomenon occurs, often aggregated in synthetic indices to carr y out national and international comparisons -i.e. the economic wealth of a country measured in GDP terms, the average longevity of the population, the education level, the average level of illiteracy, unemployment, etc. (D'Acci, 2007(D'Acci, , 2009). Nevertheless, the objective indicators may not accurately reflect the perception of well-being by the places users, since well-being is a complex emotion to be defined and, consequently, to be quantified (Das, 2008). The second component of the life quality -the subjective one -refers to the psychological dimension of the users and to their satisfaction level. This component aims to the individual assessment of the life quality conditions, in terms of perceived well-being and livability of the place to live and work, through the use of indicators that reflect moods and perceptions related to the job accomplishment level, the ambitions fulfillment, the psychological tranquility level, the satisfaction of primary needs, the gratification at individual and collective level.
Although establishing a close relationship, the well-being two dimensions -objective and subjective -are not directly related and, therefore, the increase in one does not systematically represent a growth in the other one.
The question of urban quality plays a central role in territorial regeneration policies aimed at the "realization" of accessible, safe, aesthetically pleasing, clean and adequately comfortable urban places.
The progressive transfer of the production facilities from central areas to peripheral ones or suburbs of the cities has made available urban spaces with strategically relevant locations to redesign the distribution of functions on territory and to raise the perceived quality level.
Although there is no universally shared and generalizable definition of "urban quality", the hierarchical and multidimensional aspect of this notion is known, characterized by different attributes which, in turn, are declined by more specific aspects (D'Acci, 2014). These factors refer to environmental quality, air quality, the presence of green spaces, work, social conditions, the architecture quality, the pedestrian areas presence, etc. and they can be assessed using a) monetary approaches (hedonic price method, willingness to pay, cost-benefit ratio, positional value), b) subjective approaches (life satisfaction and perceived personal well-being level), c) quantitative approaches (analysis of the urban amenities and their distribution in the urban area).
The quality of the urban environment cannot be included into a unique category whose presence (or absence) can be detected, but it depends on a complex of natural, physical-spatial, functional, anthropic-social and historical-cultural factors that contributes, as far as possible, to its definition (Agnoletti et al., 2014).
Many researchers have tried to investigate and to assess the quality of urban life notion. Richards et al. (2007) have studied the factors to improve the life quality of the inhabitants in informal housing, and the main constraints to raise the life quality in South Africa. Clark and Kahn (1988) have estimated the willingness to pay for urban cultural services such as museums, theaters, dance and music venues, zoos, concluding that the marginal benefits of cultural assets are between $ 85 and $ 54.9 million respectively for an additional theater and zoo. With reference to eight cities located in six Latin American countries, Lora et al. (2010) have identified the criteria for establishing the priorities of the political actions aimed at improving social well-being, in order to determine indicators to assess the impact of new structures and new public services on life quality and housing prices.

A model for the assessment of urban quality
The procedure proposed for the assessment of urban quality involves the disaggregation of the notion into its components. Each one is then articulated and measured using appropriate indicators. It should be noted that this approach for the assessment of urban quality must take into account qualitative and subjective aspects, as well as quantitative and objective elements. Furthermore, the model developed does not intend to reach the identification of a global and synthetic index of urban quality, but its main aim is to analyse the different aspects of quality. Therefore, the model proposed aims to quantify the urban quality indicators related to the status quo situation and it allows to assess the expected quality variation following an urban intervention.
The articulation of the developed phases borrows the logical breakdown from the Audis 2008 Urban Regeneration Charter (AA. VV., 2010, AUDIS, 2008, 2012  An innovative methodological approach for the analysis of the effects of urban interventions on property prices The indicators selected in the present research for the quantification of urban quality components can be classified as follows: -Objective indicators: they refer to tangible and measurable quality aspects. With reference to each component, the objective indicators aim to verify the presence (or absence) of elements to evaluate the urban quality and to assess i) the distances from particular qualifying or dequalifying elements and ii) the level of a specific quality aspect based on official data. -Type 1 subjective indicators: they refer to scores assigned by teams of sociologists, landscapers, architects, environmental experts, etc., in order to evaluate the capacity of an urban area to provide adequate quality standards to the community. For each indicator of this category, the judgments of "competent" subjects based on verbal scales (excellent, good, scarce) are transposed into numerical values included in scales of scores previously established. -Type 2 subjective indicators: they aim to assess aspects of perceived urban quality. With reference to the research carried out by Bonaiuto et al. (2010), the evaluation of this category of indicators is expressed through numerical judgments assigned by a sufficiently representative sample of the area users with reference to the subjective aspects of urban quality, considering the opinion of the community and/or of the urban area regular and occasional visitors and transforming the judgments in quantitative terms. The conversion of personal subjective perceptions in numerical terms involves the formulation of appropriate questionnaires and/or surveys to be submitted to a sample of individuals. The category of "type 2 -subjective indicators" allows not to limit the process of assessing urban quality exclusively to compliance with urban planning standards and/or minimum thresholds set at a general level, but to explain the personal perceptions of the subjects who "live" in a urban space and to report them in the synthetic and global judgments form. In the present research, a questionnaire has been introduced consisting of a set of verbal expressions (item), referring to the topic to evaluate. The items are characterized by an affirmative or negative sense. The evaluation is expressed in quantitative terms: to each expression the interviewees can answer through a numerical gradation of the judgment in a predetermined values range (between "0" and "5"), where the value "0" identifies a total disagreement with the affirmation of the item, whereas the value "5" indicates a condition of total agreement. Within the same quality component to be assessed, the presence of positive and negative phrases, although complicating the questionnaire compilation by the interviewees, allows to maximize the answers consistency.
Following the different items evaluation, the data aggregation phase is carried out using calculation tables with which it is possible to determine the average values of each aspect of the perceived urban quality. The operation should take into account the presence in the questionnaire of items with a positive sense and others with a negative sense. For example, according to the mentioned research by Bonaiuto et al. (2010), positive items are considered for the relative values recorded during the questionnaire administration, whereas the negative ones are re-evaluated as the difference between the maximum value and the score attributed by the interviewee. For the present analysis, the questionnaire has been borrowed from the conclusions of Fornara et al. (2010), in order to define the "type 2 -subjective indicators" for the evaluation of the perceived urban quality (item). For each of the six urban quality components, in Table 2  orderly and sequential succession of steps to be performed, and it aims to provide a methodologicaloperational practice able of explaining an urban redevelopment project effects.
The proposed operational tool intends to be a generally valid theoretical model that can be used by Public Administrations or by private investors in any territorial context, in order to suppor t the decision-making processes relating to a urban intervention. In fact, this model is independent from the spatial and temporal conditions of the specific case study, and its correct use depends exclusively on the quantity and quality of the available data. In Table 3 the protocol is reported: for each phase, the main actions to be performed are illustrated.

A PROTOCOL FOR THE ANALYSIS OF THE EFFECTS OF URBAN INTERVENTIONS ON PROPERTY PRICES
The identification of the social, functional, economic, environmental effects that can be generated by an urban transformation initiative, constitutes a useful operation to guide the territory government decisions. In this sense, the leading role provided by the Appraisal and Valuation in the urban and territorial transformation processes should be appropriate in all project phases (Agnoletti et al., 2014).
In the framework outlined, a procedural protocol for the analysis of the effects of urban interventions on property prices is proposed. This procedure is configured as an

PHASE 3
Application of the econometric technique in the ante-project situation.
3.1 Definition of the function that links selling prices and the intrinsic and extrinsic factors that contribute to their formation in the current situation.

PHASE 4
Analysis of the functional links obtained in the ante-project situation.
4.1 Determination of the marginal contribution of each variable (intrinsic and extrinsic) to examine the percentage incidence of each variable on the property prices in the ante-project situation.
PHASE 5 Assessment of the urban quality level in the post-project situation.
5.1 Application of the proposed model for the urban quality assessment with reference to the hypothetical future state (post-project situation) in order to evalue the modification of the extrinsic variables values.

PHASE 6
Determination of the new property prices expected in the post-project situation.
6.1 Replacement in the function identified through the step 3.1 of the "new" extrinsic variables values for which, following the new functions proposed, a variation is expected.

AN APPLICATION OF THE ASSESSMENT PROTOCOL
With reference to four urban interventions currently in progress in the city of Bari (Puglia region capital), the assessment protocol has been implemented.
Each intervention is located in one of the four municipal trade areas (central, semicentral, peripheral, suburban) considering the geographical distribution developed by the Real Estate Market Observatory (OMI) of the Italian Revenue Agency (http://www.agenziaentrate.gov.it/).
The urban interventions selected for the analysis are different by location and type. In fact, they concern respectively: • a property enhancement project to be implemented in the central trade area that concerns the realization of the "Polo del Contemporaneo"; • a redevolpment initiative to regenerate "via Giovanni Amendola" in the semicentral trade area; • the regeneration of the "San Girolamo" waterfront in the peripheral trade area; • the recovery and improvement of the "Giovanni Paolo II" Park in the San Paolo district for the suburban trade area.

Description of the case study
Intervention 1. The realization of the "Polo del Contemporaneo"

Description of the current state
The central location of the Margherita Theater, of the former Fish Market building and of the Sala Murat -the three buildings of the "Polo del Contemporaneo" -is strategic towards the historic center and, more generally, the whole city. 7.2 Identification and illustration of the possible reasons for the increases and/or decreases assumed in order to validate their reasonableness and congruence.
PHASE 8 Summary of the results obtained.
8.1 Overall assessment of the possible effects expected, not only with regards to variations in property prices, but also in terms of raising the urban, social and environmental quality level associated with the transformation intervention.
An innovative methodological approach for the analysis of the effects of urban interventions on property prices story volume, marked by an orderly horizontal and vertical score. From the early 1900s until the 1990s, the building round floor hosted the fish market, whereas the upper floor was the municipal police headquarters. In the recent years, the property has been at forst used as a farmers' market and then as a bazaar for clothes, leatherwear, and other goods.
Entitled to Gioacchino Murat, the Sala Murat traces the older Meat Market structure, i.e. the first public property in the city of Bari that was built in 1817 and was demolished for safety reasons (as it was strongly crumbling), after the Second World War. The current building is used as an exhibition space.

The redevelopment project
Signed by the Territorial Enhancement Agreement between the Municipality of Bari, the Puglia Region and the Ministry of Cultural Heritage and Activities and Tourism, the "Polo del Contemporaneo" project ( Figure  3) aims to constitute a new multidisciplinary cultural hub of the city, as a regional, national and international tourism attraction.
The three buildings of the Polo will become the venue for events related mainly to modern and contemporary art.
Currently, on Margherita Theater and on the former Fish Market recovery and enhancement interventions are carried out. In particular, the functional recovery of the Margherita Theater intends to restore the building to its old function as a cluster able of hosting contemporary and musical art events.
The former Fish Market redevelopment project involves the building functional conversion, by the realization of a typical food and wine market and artistic local products, on the model of the Spanish markets, on the ground floor; an exhibition space for contemporary arts, laboratories, ateliers to rent, suites for artist residences, Polo del Contemporaneo offices on the first floor; finally, the terrace will be transformed into a roof garden, or a green space organised as an urban garden, to host art events, such as vernissage, inaugurations and previews.

Description of the current state
Approximately 3 kilometers long and constantly congested, "via Giovanni Amendola" (Fig. 4) is one of the most important road of entry and exit from the city of Bari.

The redevelopment project
The project involves the widening of "via Giovanni Amendola". In particular, the intervention concerns the road section between via Conte Giusso and via Omodeo, for a length of about 1.1 kilometers. The roadworks include: the widening of the street track with two lanes in each direction and central traffic island; the construction of three roundabouts at viale Einaudi, via Laforgia and via Hahnemann and new sidewalks; the introduction of trees and new pedestrian crossings on the central traffic island and the traffic lights removal (Fig. 5). In brief, the intervention aims to create a more sustainable and efficient urban road, also thanks to the inclusion of new urban furniture elements able to renovate the road image.

Description of the current state
Located in the homonymous district, the "San Girolamo" waterfront extends for one kilometer. Since the late  1980s, the imposing residential building development in the urban area, has led to a significant increase in congestion phenomena, without solving the area marginality caused by the absence of an adequate infrastructure system, in terms of viability and services ( Fig. 6).
With reference to the neighborhood and to the area overlooking the coast, there is a relevant demand for public services not satisfied, above all due to the lack of collective spaces such as "places for socializing".
Currently the commercial intended use located on the buildings ground floors along the coastline are often unused and the promenade is considered exclusively as a fast crossing on the edge rather than as a service axis of the neighborhood. This phenomenon contributes to emphasize the waterfront marginality with respect to the neighborhood internal area.

The redevelopment project
The redevelopment intervention of the "San Girolamo" waterfront provides for the recovery and its functional and landscape transformation. The intervention aims to determinate a new landscape and environmental configuration overlooking the sea and new modalities for the spaces uses, with new ways of using the spaces and to involve the economic and social sectors of the neighborhood.
The waterfront redevelopment (Fig. 7) provides for its pedestrianization with the creation of an "square on the sea" of 8,000 m 2 on two levels, with about 600 seatings in front of the sea, and the introduction of new urban functions, i.e. service activities, places for leisure, sport, swimming and social events.

Intervention 4. The recovery project of "Giovanni Paolo II"Park in the San Paolo district
Description of the current state The "Giovanni Paolo II" Park constitutes a green space located in the city of Bari, between Viale Europa and Viale delle Regioni, in the San Paolo district.
The area is currently characterized by a strong degradation state. Crossing the park, portions of broken fences, ruined or damaged public lighting, signs, decayed and vandalized brick wall parts, degraded street furniture and unused walled public toilets are found.
The park requires strong interventions to recover the open space and its elements, as well as to restore public hygiene and safety, in order to make the garden accessible as a place for recreation, aggregation and socialization.
Currently, the park is unused. The neglect state (Fig. 8) does not allow neighborhood inhabitants to enjoy this area as a public garden or a pedestrian crossing.
journal valori e valutazioni No. 26 -2020 34 Figure 6 -"San Girolamo" waterfront -current state An innovative methodological approach for the analysis of the effects of urban interventions on property prices The redevelopment project The "Giovanni Paolo II" Park project is part of the wider urban redevelopment program which includes fourteen parks for the city of Bari. The goal of the interventions concerns the provision of facilities and accessories in the neighborhoods to promote the amateur sports, favoring the socialization and aggregation places realization, counteracting social marginalization and isolation. The "Giovanni Paolo II" Park intervention ( Fig. 9) aims at the skating rink area recovery, whose degraded conditions negatively influence the urban context aesthetics.

The collected data
For each of the four municipal trade areas of the city of Bari, a sample of two hundred residential properties sold in the 2017-2019 period (in particular from the second half of 2017 to the first half of 2019) has been collected. For each property, the selling price and the intrinsic and extrinsic factors that, on the basis of the indications provided by the market operators in the area and of the data generated by the OMI of the Italian Revenue Agency, are taken into account in the negotiation phases by local operators (sellers and buyers) (Bourassa et al., 2003), have been detected.

Variables of the model
With reference to the model to be developed and tested in the present research, the dependent variable is the total selling price (P), expressed in € (euro).
The factors related to perceived urban quality are assessed by submitting the questionnaire proposed for the research, to a sample of two hundred subjects randomly selected for each municipal trade area (eight hundred subjects in total). The questionnaire has been first administered with reference to the "ante-project" situation, in order to assess the urban quality level in the current state and, subsequently, to the "post-project" situation, to evaluate the level quality perceived variation.
The independent variables considered are described below. -Presence of the lift in the building where the property is located -A. This variable is considered as a dummy variable (Hardy, 1993): the value "one" indicates the lift presence, whereas the value "zero" represents the absence of the service; -Presence of the parking space in the building where the property is located -P. The variable is assessed as a dummy variable, where the score "1" means the presence of the car space, whereas the score "0" its lack.
-Quality of the maintenance conditions of the property -Sc. The variable is evaluated as a qualitative variable and it is synthesized by the numerical score: in particular, the score "1" is assigned to the properties that require significant refurbishment interventions, the score "3" refers to buildings characterized by good maintenance conditions and the score "5" indicates properties whose maintenance conditions are excellent.

Extrinsic variable
With reference to the procedure for the assessment of the urban quality level of the area in which each building of the four study samples is located, the quality components (architectural quality, planning quality, environmental quality, landscape quality, quality of public space, social quality) and the indicators as classified in journal valori e valutazioni No. 26 -2020 35 Figure 8 -"Giovanni Paolo II" Park -current state Figure 9 -"Giovanni Paolo II" Park -project situation paragraph 3.2 of the present research (objective indicators, "type 1 -subjective indicators" and "type 2subjective indicators") have been used. For each quality component, the most influential objective and "type 1subjective indicators" taken into account by buyers and sellers in the negotiations phases in the residential market for the four trade areas of the city of Bari, are reported below. Each perceived urban quality component shown in the questionnaire constitutes an extrinsic variable to be analyzed.

Architectural quality
Type 1 -subjective indicators: -Maintenance conditions of the buildings facades adjacent to the property -Sf, assessed through a scores scale assigned by a experts panel, where the score "1" indicates a very bad state; the score "3" indicates a good state and the score "5" an excellent one.

Planning quality
Objective indicators: -Distance of the property from the nearest highway (Tangenziale of the city of Bari), calculated in kilometers it takes to get there by car -Dt; Distance of the property from the nearest railway station calculated in kilometers it takes to walk to it -Ds.

Environmental quality
Objective indicator: -Distance of the property from the nearest urban green space, calculated in Kilometers it takes to walk to it -Dv. For the cases considered, the areas selected are the equipped green spaces, squares and public gardens most used by the inhabitants of the city of Bari. In particular, these areas are: • Gardens of Piazza Umberto I -located in the central municipal trade area.
• Piazza Giuseppe Garibaldi -located in the central municipal trade area.
• Parco 2 giugno -located in the semicentral municipal trade area, close to the central one.
• Punta Perotti Park -located into the central municipal trade area on the border adjacent to the peripheral one.
• Pineta San Francesco -located in the peripheral municipal trade area.
• Pineta Giuseppe Romita -located in the north-western peripheral of the city of Bari in the suburban municipal trade area.
Type 1 -subjective indicators: -the road private and public vehicular traffic (buses) level of the building area in which each property is located -T, assessed through a scale of scores assigned by a team of experts, where the score "1" indicates a road characterized by high traffic intensity, the score "3" indicates a medium traffic intensity, the score "5" refers to roads characterized by low traffic congestion.

Landscape quality
Objective indicator: -Distance of the property from the landmark for the local community -architectural and landascape emergence (Araldo di Crollalanza waterfront of the city of Bari ), calculated in Kilometers it takes to walk to it -Dl;

Quality of the public space
Type 1 -subjective indicators: -Maintenance conditions of the public spaces furniture (public lighting lamps, waste baskets, benches, planters, parking canopies, display boards for billboards, etc.), adjacent to the property -Sa. The variable is assessed in qualitative terms through a scale of scores attributed by panels of experts: the score "1" " indicates a bad maintenance conditions of the public spaces, the score "3" refers to a good state, the score "5" an excellent state.

Social quality
Objective indicator: -Distance of the property from the nearest food market or grocery shop, calculated in kilometers it takes to walk to it -Dm.

The econometric technique
Starting from the sample data, Evolutionary Polynomial Regression (EPR) is the technique implemented to identify the selling price function starting from the study sample data.
The technique implements a genetic algorithm to combine numerical and symbolic regression methods using polynomial structures (Goldberg, 1989, Giustolisi et al., 2006. Known the dependent variable (Y) and the independent variables (Xi), having defined the parameters useful to return the functional form able to determine the relationship Y = f (Xi), the generic expression of the non-linear model implemented in EPR is summarized by Eq. (1) journal valori e valutazioni No. 26 -2020 An innovative methodological approach for the analysis of the effects of urban interventions on property prices where a 0 is the constant additive term, n is the number of additive terms, i.e., the length of the polynomial expression (constant additive term excluded), a i represents the numerical parameter to be assessed for each additive term, X i is the candidate explanatory variables to be selected by the model, (i, l) -with l = (1, .. ., 2j) -is the exponent of the l-th variable within the i-th additive term, f is a function selected by the user from a set of candidate mathematical expression. The exponents (i, l) are also choosen by the user from a range of candidate real numbers.
The central idea of EPR is to search the best function form, i.e. a combination of the independent variables vectors (the chosen variables, model inputs) by performing a regression with the Least Squares Method to obtain the coefficients value of each variable. The phases that define the econometric elaboration process are: i) identification of the model structure; ii) assessment of the parameters. The quantity and complexity of the solutions that the technique generates depend on the maximum terms number and on the exponents that the user defines in the processing preliminary phase.
A recent version of EPR (Giustolisi and Savic, 2009), called EPR-MOGA, applies a multi-objective evolutionary genetic algorithm, as an optimization strategy based on the Pareto frontier. The proposed technique is able to simultaneously pursue different objective functions, such as to define an optimal Pareto frontier of the fixed conflictual objectives, that aim at i) the maximization of the model accuracy, through the satisfaction of appropriate statistical indicators; ii) the maximization of the model parsimony, through the minimization of the number of coefficients (a i ) of the equation; iii) the reduction of the complexity of the model, through the minimization of the number of explanatory variables (Xi) of the final equation.
The resulting optimal Pareto front contains the set of the best mathematical models obtained by considering the best compromise between the accuracy of the model (objective i) and its complexity/parsimony (objective ii and objective iii). At the end of the modeling phase, the optimization strategy allows to obtain a series of equations for the three objectives considered. In this way, a range of solutions is offered to the operator, among which it is possible to select the most appropriate solution according to the specific needs, the knowledge of the phenomenon and the quantity and quality of experimental data used. The main advantage of EPR-MOGA technique is the possibility to obtain a set of expressions characterized by a different statistical accuracy and mathematical structure complexity levels. It should be noted that it is not necessary to postulate the "right" form of the model structure before the analysis, since it is the algorithm implemented by the procedure that generates different models. The choice of the best compromise solution between statistical performance and the complexity of the expression is left to the operator, in order to select the most appropriate models according to the specific situation.
With reference to the applications of the EPR-MOGA technique to the real estate market sector, the research in the literature is very few and recent (Morano et al., 2015, Tajani et al., 2015, Morano et al., 2018. In the present research a further evolution of EPR has been proposed and tested (in addition to the best performances obtainable with the EPR-MOGA Pareto front), that develops generalized prediction models to identify the functional relationships able to simultaneously describe the selling prices mechanism in different study samples (for example, in different territorial contexts). This technique, called Multi-Case Strategy for EPR (MCS-EPR) is used to study a phenomenon in different cases/contexts, in order to represent and interpret it simultaneously (Berardi et al., 2007, Savic et al. 2009). In the situations with different case studies, the MCS-EPR technique allows to define a "generalized" equation for determining the price, able to identify the influential factors between those initially considered and the related functional correlations, valid for all the samples analyzed (territorial contexts). The study samples may concern different urban areas located in the same city or geographical areas located in different cities on the national territory, for which the study of the influence of specific explanatory variables on selling prices is carried out (Morano et al., 2019). Applications of MCS-EPR in the reference literature (Giustolisi et al., 2007;Berardi et al., 2007) have demonstrated the ability of the technique to generate robust models for the representation and interpretation of complex real phenomena.
The mathematical logic of the MCS-EPR technique employs the EPR-MOGA genetic algorithm to identify the polynomial coefficient values for all considered data samples that simultaneously satisfy the three objective functions -maximization of statistical performance, minimization of the number of coefficients and minimization of the number of variables -for all analyzed case studies. Therefore, the MCS-EPR strategy searches for a unique model structure, that is the combination of the explanatory variables able of defining a generalized model valid for all case studies. According to each sample specificity, the genetic algorithm of MCS-EPR returns different coefficients -a 0 and a i in Eq.
(1) -due to the phenomena (e.g. of the market) that characterize the datasets of the different cases analyzed. Thus, the functional correlations (in absolute terms) and the explanatory variables of the equations returned by MCS-EPR for the case studies are the same ones, whereas the coefficients (a 0 and a i ) are different for each sample considered.
journal valori e valutazioni No. 26 -2020 The statistical performance of the analysis carried out by MCS-EPR for each equation is verified using different indicators (R 2 corrected, AIC, RMSE) and tests (ten-fold cross-validation). Furthermore, in order to obtain a model that fits as much as possible to the different samples data set, a generalized Coefficient of Determination (CoD MCS ) defined in Eq.
(2), is determined: (2) where m is the number of data samples for which a generalized prediction model is required (k = 1, . . . , m); N k is the size (i.e., number of individuals) of the k-th data sample; N is the total number of individuals that constitute all the m data samples in analysis; y k is the value of the dependent variable estimated by the technique through the statistical inference on the k-th vector of parameters, y detected is the corresponding observation, and y detected is the average value of the collected values in the m data samples.
Similarly as a classic Coefficient of determination, the closer to the unit value the CoD MCS is, the more suitable the model structure is in representing the overall observed dataset.
In Figure 10 the evolution of the econometric technique used and of the objectives pursued by the underlying genetic algorithm is summarized.

Determination of the generalized model in the "ante-project" situation
The MCS-EPR technique has been initially implemented on the four case studies in the "ante-project" situation. For all the samples, the dependent variable is constituted by the natural logarithm of the selling price (Y = ln(P)), taking into account the results obtained in several studies (Lynch et al., 2004).   An innovative methodological approach for the analysis of the effects of urban interventions on property prices variables: distance of the property from the nearest urban green space (Dv), presence of the parking space in the building where the property is located (P), distance of the property from the nearest food market or grocery shop (Dm), maintenance conditions of the buildings facades adjacent to the property (Sf), distance of the property from the nearest highway (Dt).
Given the generalized functional form, valid for all four case studies, Table 4 shows the values of the coefficients for each municipal trade area analyzed.
In Table 5 the four equations for the municipal trade areas into which the city of Bari is divided, are reported.
It should be observed that the quality of the maintenance conditions of the property (Sc), the presence of the lift (A), the distance from the nearest railway station (Ds), the perceived quality of the public space (Qp) and the total surface of the property (S) are in all four equations with a non-zero multiplicative coefficient. For the other factors of the generalized model, a different market behavior occurs for each of the analyzed samples.
With reference to the variables of perceived urban quality, the equation for the study sample of the suburban municipal trade area includes all the characteristics related to the quality of urban spaceperceived planning quality (Qu), perceived social quality (Qs), perceived quality of public space (Qp), perceived environmental quality (Qn) and perceived architectural quality (Qa); in the equations obtained for the study samples of the peripheral and central municipal trade areas, the variables Qu (perceived planning quality), Qn (perceived environmental quality), Qp (perceived quality of public space) and Qs (perceived social quality) are identified as influential, whereas for Qa (perceived architectural quality) there is no appreciation in the two reference markets; finally, the equation related to the study sample of the semicentral municipal trade area exclusively selects the variable Qp (perceived quality of public space).
For each municipal trade area of the city of Bari,Figures 11,12,13 and 14 show the functional correlations between the selling prices and the characteristics of urban quality level.

Assessment of the urban quality level in the "post-project" situation
Each of the four interventions considered in the present research generates a variation in the urban quality level into the project area and in the surrounding context. In the functional expressions obtained through the implementation of the MCS-EPR technique on the starting data ("ante-project" situation), this phenomenon translates into variations of the extrinsic factor values selected by the generalized model. The determination of the new values of the factors for which a variation is expected following the implementation of each intervention has carried out through the use of the criteria illustrated (see paragraph 3.2) and also already defined in the present work (objective indicators, type 1subjective indicators and type 2 -subjective indicators). For the assessment of the perceived quality indicators, the questionnaire has been administered to the same sample of individuals interviewed for the perceived quality measurement in the "ante-project" situation. Following the illustration of each project analyzed for each municipal trade area in the city of Bari, each individual has been asked to formulate a predictive judgment on the perceived quality variation, prefiguring the urban area in the "post-project" situation.

Determination of property prices in the "postproject" situation
The procedure implemented for the assessment of the effects of each urban transformation intervention on property prices is based on the hypothesis that the functional relationships expressed in the generalized model obtained for the "ante-project" situation (Eq. (3)) do not vary after each project realization.
Therefore, it is assumed that the interventions to be carried out in each municipal trade area of the city of Bari do not generate variation in the urban system and that the structural dynamics of the real estate market and, in particular, of the residential sector, are the same of the current state. In this sense, the most influencing factors for the sellers and the buyers do not change compared to those considered in the "ante-project" situation.
journal valori e valutazioni No. 26 -2020 39 This is a strong hypothesis.
However, under this hypothesis, it is possible to apply the equations previously obtained (Table 5) to determine the property prices in the "post-project" situation, introducing the variations in urban quality factors assessed for the projects realization.
In Table 6 the four mathematical expressions of the price function for the municipal trade areas of the city of Bari are reported, highlighting (in bold) the variables relating to the urban quality for which, following the project, a variation of the values is expected. The semicentral, peripheral and suburban trade areas of the city of Bari concern discontinuous urban areas: although spatially separated, these contexts are currently characterized by similar market phenomena according to the dynamics outlined by the Revenue Agency.

Comparison of the assessed values in the "ante project" and "post project" situations
The outputs of the analyzes carried out give rise to interesting considerations.
According to the empirical phenomena normally expected, for all the cases, the results obtained show a significant influence on the properties close to the intervention area and a decrease of the market effects on the most distant areas.
The graph in Figure 15 for the central municipal trade area shows a higher variation in property prices for residential units located in the immediate surroundings of the intervention; the propagation effect decreases with the increasing of the distance, and it is equal to the zero value for the properties far from the Murattiano district in which the three project buildings are located. On the other hand, it should be noted that in the historical center of the city, located in the north of the urban center, although close to the intervention, there are no effects in terms of variations in property values: this fact is connected to the specificity of the historic center, characterized by different market and socio-economic factors compared to those of the "Murattiano" district, which neutralize the redevelopment positive effects. The average increase in property values recorded in the central municipal trade area is equal to approximately +6%: this contribution confirms the relevance of the construction of the "Polo del Contemporaneo" on the increase of the urban quality perceived level in the central area in architectural, social and public space terms. The result appears consistent with the expected empirical trend, since the project makes it possible to improve the livability conditions of the area. This  phenomenon is perceived by the local real estate market, through the appreciation of historical and architectural buildings able of increasing the cultural offer of the city and promoting a higher touristic flow.
With reference to the semicentral municipal trade area, the graph in Figure 16 highlights the effects of the redevelopment of "via Giovanni Amendola" on the property prices of the residential units next to the project, for which an increase range between [+3%, +5%] is assessed. Also in this case, the real estate market effects decrease in corrispondence to greater distance from the intervention area. Moreover, the impacts are nil in the area of the semicentral municipal trade area located to the west of the urban center, excessively distant from the intervention.
For the peripheral municipal trade area, the results obtained and represented in Figure 17, terms of improving the urban quality level in the sorrounding context. In fact, the average increase in property prices is equal to about +32%. It highlights the importance of the redevelopment project for the peripheral area of the city of Bari. The propagation effects are nullified for the properties located in the separate peripheral areas from the urban context in which the intervention is located.
The analysis of Figure 18 for the suburban municipal trade area allows to identify three possible scenarios of property values variation in the "post-project" situation: i) a significant increase in property prices for the residential units near the "Giovanni Paolo II" Park; ii) the absence of effects for properties further away from the project and for properties located in the areas of the suburban municipal trade areas disconnected from the area in which the urban park is located; iii) a decrease in property values for the housing units in the south-west of the project, near the San Paolo hospital and recently built. Therefore, the scenario iii) reflects a possible variation in market demand from the South-West area of the intervention towards houses close to "Giovanni Paolo II" Park. These properties could benefit from the project implementation, in terms of market values, for the realization of an urban amenity that, currently, is represented by a degraded green area.
The average increase in property prices for the suburban municipal trade area is assessed equal to about +1.4%.
In Table 7 the average percentage variations in property prices in the four municipal trade areas of the city of Bari following the implementation of the urban transformation interventions examined, are shown.
An innovative methodological approach for the analysis of the effects of urban interventions on property prices

CONCLUSIONS
The goal of the analysis has concerned the definition and testing of an ex ante evaluation protocol of the effects of urban transformation interventions on property prices.
The research has focused on two current and relevant issues: the first is related to urban quality; the second concerns the link between interventions, urban quality and property prices. With reference to these two issues, the research has proposed and tested a new model for assessing urban quality, based on the main strengths of the methodological approaches currently used for its evaluation.
The urban spaces functional reconversion is one of the most important and debated goals in the context of public policies for governing the territor y. The redevelopment interventions of degraded or abandoned urban areas allows: to transform underused city portions, located in central and/or strategically relevant positions; to give "quality" on areas that are strongly damaged; to enhance rundown buildings; to provide the city with new places for recreation and social gathering.
journal valori e valutazioni No. 26 -2020 45 Figure 18 -Graphic representation of the effects on property prices generated by the recovery project of "Giovanni Paolo II" Park in the suburban municipal trade area

Table 7 -Average increases in property prices following the implementation of each urban intervention and with reference to each municipal trade area
With reference to urban quality analysis, an innovative model has been proposed aimed at assessing the different quality components in quantitative terms. Borrowing the logic of the existing scientific literature tools, the model provides for the quality notion disarticulation in its components and the subsequent evaluation and quantification of them through appropriate indicators.
With regards to the aim of the research, an operational methodological approach has been defined for the analysis of the effects of urban transformation interventions in terms of variations in property prices.
The developed approach has led to the procedural protocol definition, divided into phases, able to determine the urban redevelopment effects on the real estate market. This decision support tool for the Public Administration or private investors could be implemented in any territorial context and for any redevelopment initiative. In particular, the protocol can be used in the planning urban redevelopment interventions preliminary phases to i) verify the effects of different proposed projects in terms of property values and, possibly, recalibrating the design solution to be implemented; ii) compare different design alternatives in order to choose the "best" solution; iii) orient the public and/or for community works planning towards initiatives whose expected regenerative effects are higher; iv) support the negotiations, in the case of initiatives to be implemented in public-private partnership. In the present research, the verification of the effects generated by the redevelopment has been investigated through the study of the variation of property values in the municipal trade areas in the "ante-project" and "post-project" situations.
The protocol has been applied in the city of Bari (Southern Italy). First, four urban interventions in progress have been selected. Each of them is located in one of the four municipal trade areas (central, semicentral, peripheral and suburban) identified by the OMI of the Italian Revenue Agency. For each trade area, a sample of recently sold residential properties has been detected. The implemented econometric procedure has allowed to obtain a generalized price function, valid for the entire municipal area of Bari and able of identifying the best variables set that influences the selling prices formation in the "ante-project" and "post-project" situations. The main advantage of the technique used concerns the ability to generate descriptive models of the property prices formation mechanisms, characterized by a high statistical reliability and at the same time by easily interpretable functional correlations, avoiding the creation of "black boxes" difficult to understand for the possible users. It is evident that the descriptive and predictive potential of the models obtained significantly depends on the size of the study samples: in fact, if the database is not significant, the procedure used may not be able to generate sufficiently reliable outputs.
The developed evaluation protocol will be able to support the traditional financial and economic projects feasibility verification tools currently used, representing a further decision support for public and private operators. With reference to the operations carried out in publicprivate partnerships, the methodological approach will guide the selection of projects that provide for an increase in the urban quality level and a growth in expected property values. This condition allows to identify the initiatives able to have fiscal effects, as generally higher property value corrisponds to higher revenues for public finance.
The proposed procedural protocol is characterized by the flexibility of its phases, allowing the constant monitoring of the different steps and the adaptation to different inputs that may derive from reference context evolutions: the possibility of modeling the actions succession to be carried out to the different territorial areas allows to implement the protocol also to other urban quality aspects, i.e. the health and, more generally, to environmental quality aspects, to the presence of pedestrian road and/or cycle paths. These changes may be proposed by public administrators, by operators in the reference market and by local communities with reference to the characteristics of the urban areas to be redeveloped and to the functional reconversion projects considered.
The work is part of a current and wider research line. The issue of urban redevelopment, as the degraded urban areas regeneration and the existing public and private property assets enhancement, constitutes a constantly evolving issue in the government policies which, linked to the scarce Public Administrations financial resources, requires accurate and adequate selection of the interventions to be implemented.
Future research developments may concern the analysis of synergistic effects of each intervention in a specific municipal trade area on the other urban contexts and, in general, on the entire urban system. In this way, the protocol thus improved will be able to constitute a support to redefine and update the market trade areas perimeters following urban redevelopment interventions.