Municipal approaches to suburban densification: Understanding the role of planners’ interest and agency

Abstract

Suburban areas, characterised by their low density and high housing quality, emerge as both a promising potential and a challenge for densification. Despite their potential and political objectives to prioritise densification, municipalities frequently continue to depend on greenfield development, often merely extending suburban areas and low-density housing. This research explores the role of planners’ interest and agency in shaping suburban densification policies and outcomes, with the aim of understanding why municipalities seemingly fail to approach and implement densification in suburban areas. Through a qualitative study of six German municipalities, this research reveals considerable variation in planners’ interest to pursue suburban densification, with some opposing it while others pursue it despite limited resources. Furthermore, the study shows that planners’ agency is shaped by both external factors, such as the political power of landowners, and internal factors, including planners’ own strategic actions. Specifically, planners who actively pursued suburban densification used a flexible approach to planning instruments to broaden their possibility to act and shape densification outcomes.

Introduction

Suburban living has historically been associated with social stability, cohesion and high-quality, owner-occupied, low-density housing (Fava, 1956). With their quiet surroundings and expansive living concepts, suburban areas appear to be an unlikely candidate for re-evaluating housing density (Charmes and Keil, 2015; Frank, 2018). Nonetheless, suburban areas provide a platform for discussing sustainable land use issues due to these very characteristics. Given the constraints of housing shortages and the desire to reduce land take, how can these expansive neighbourhoods persist? In this view, suburban areas present an opportunity to reconsider urban density by offering untapped potential for development. However, it is challenging to unlock this potential. The fragmented ownership of small-scale properties and the deeply ingrained normative views of suburbia can present substantial obstacles, making intervention in these areas both challenging and controversial.

As urban areas across Europe strive for sustainable land use, urban planning policies are placing greater emphasis on densification to manage spatial development and housing needs (Dembski et al., 2020). Densification policies aim to address growing housing demand while also achieving the objective of reducing land uptake. Densification refers to increasing the number of housing units or residents in a given area (Broitman and Koomen, 2015). The goal thus is to use the already built-up areas of cities more efficiently, reducing land uptake and limiting the need for greenfield development on the outskirts of cities.

Suburban areas are often shaped by their low built density as well as a low population density. These attributes are partially determined by planning regulations on low density buildings and are further reinforced by demographic trends leading to so-called empty nesters. However, when dealing with planning intervention in suburban areas, the density should not only be looked at as an urban structure but must also be considered as an expression of power (Charmes et al., 2021; Charmes and Keil, 2015). Residents purposefully choose suburban residential areas, aiming for a suburban way of living, characterised by sociocultural and demographic homogeneity (Charmes, 2009; Charmes et al., 2021; Frank, 2020). In this context, the political nature of densification policies is pronounced. Residents of suburban areas are particularly resistant to densification projects due to a fear of losing their high-quality living environment (Wicki and Kaufmann, 2022). However, studies have shown that there still are significant densification processes happening in suburban areas, albeit focusing on the individual interests of homeowners and often being overlooked by local planning authorities ( Bibby et al., 2020; Dunning et al., 2020; Pinnegar et al., 2015). Suburban areas offer potential for densification, yet they often lack effective strategic planning and require careful oversight to manage development activities.

Germany offers an intriguing case for studying suburban densification due to its suburbanisation trends and polycentric structure. Germany’s polycentric urban structure mostly stems from processes of suburbanisation in past developments (Dembski et al., 2021; Hesse and Siedentop, 2018). The resulting regions in Germany, like the Rhein–Ruhr metropolitan region, present a prototype of the in-between-city as described by Sieverts (2003). The importance of suburban areas in Germany highlights the need to see them as important parts of urban regions rather than static peripheries, particularly given recent discussions about a renewed increase in suburbanisation in Germany (Hesse and Siedentop, 2018; Siedentop, 2024). These evolving suburban regions require consideration in the efforts to achieve sustainable urban development.

Despite the long-standing suburbanisation trends, political efforts to reduce land take became increasingly prominent in the early 2000s in Germany. Despite ambitious land take reduction goals (Federal Government of Germany (FGG), 2002), land take continues to surpass these targets, and a substantial share of the spatial development of municipalities still takes place in the form of greenfield development for low-density housing (Eichhorn et al., 2024a; Siedentop, 2024). While planning authorities are accustomed to planning as a means of regulating new development in a single, concentrated greenfield area, they encounter challenges in the form of the fragmented structure of densification efforts and the need to address the built environment and local landowners. Accordingly, the difficulty of interfering with legally well-protected private property rights is pointed out as a major obstacle to the densification efforts of local authorities (Dembski et al., 2020). Moreover, municipalities might have a fiscal interest in promoting low-density housing to attract wealthy residents, assuming that such development might enhance their tax revenues (Götze and Hartmann, 2021). Despite political goals to reduce land uptake, planning authorities seem to face multiple challenges in the practical implementation of densification.

The densification of suburban areas remains an understudied topic, with limited research on the implementation in practice. Earlier studies have emphasised the importance of the normative environment for the densification of suburban areas (Charmes and Keil, 2015), showing how this influences the application of instruments (Jehling et al., 2020), municipal decisions on more or less interventionist strategies (Touati-Morel, 2015), and the role of politicians in negotiating densification in suburban areas (Rousseau, 2015). Still, a gap remains in understanding why, despite ongoing discussions and political pursuits of densification, suburban areas resist municipal densification efforts. The objective of this research is to understand the local context of municipalities’ densification efforts, particularly the role of planners’ interest and agency in the local context and processes of densification. Ultimately, this raises the question: how do the interest and agency of planners shape suburban densification?

This study uses a qualitative research design to get a better understanding of how planners navigate suburban densification. Data was collected through interviews with municipal employees from various departments responsible for planning, housing or land management. These interviews were carried out in six municipalities across Germany, selected from two city-regions characterised by their polycentric structure and suburban areas: the Frankfurt Rhine–Main Region and the Ruhr Agglomeration.

The structure of this contribution is as follows: the following section provides the theoretical framework for the municipal pursuit of suburban densification, highlighting the strategies and challenges as well as the German national framework guiding the implementation. The third section gives an overview of the interview process. The fourth section presents the findings on the interest and agency of planners derived from the interviews, highlighting organisational challenges, surprising flexibility in planners approaches and how the political power of landowners shapes the processes. The fifth section discusses these findings, followed by the concluding section with an overview of the interest and agency of planners and their impact on the implementation of suburban densification.

Theoretical framework for analysing suburban densification

Densifying suburban areas is a process that involves the interplay of various actors, including urban planners, local politicians, developers and residents. The interests and behaviours of these actors are complex, yet crucial for the success of densification efforts. At the heart of the process are planners, who play a crucial role in shaping policies, influencing the importance attached to policies and ideas and promoting development projects (Purkarthofer and Stead, 2023). Planners mobilise ‘their agency potential to navigate their institutional and political economy context in order to advance their professional interest’ (Filion, 2021: 256). Understanding the agency of actors has been relevant to studies on planning practices (Filion, 2021; Healey and Barrett, 1990; Purkarthofer and Stead, 2023), and also more specifically in the densification context (Ehrhardt et al., 2025; Eichhorn et al., 2024b; Teller, 2021). For suburban densification, planners’ interest and agency can influence whether and how they choose to promote suburban densification.

Municipal strategies and challenges

The urban structure of suburban areas is changed through processes of densification, despite municipalities’ difficulties in densifying and the resistance of residents. Individual landowners and smaller developers initiate and carry out much of this densification (Puustinen et al., 2022). Through small-scale and incremental decisions at a household level, landowners gradually transform the structure of suburban areas. These decisions are shaped by diverse motivations, including economic, social and personal preferences (Pinnegar et al., 2015; Wiesel et al., 2013). Individually planned densification projects cumulatively contribute to significant changes in neighbourhoods (Bibby et al., 2020). This type of densification is often referred to as incremental or soft densification, indicating the small scale of development that does not lead to a radical change in the urban form of the area (Touati-Morel, 2015).

In these cases, landowners are making decisions on densification and the built environment, often with little or no strategic planning intervention (Bibby et al., 2020; Dunning et al., 2020). Developments frequently occur outside the intended scope of public policies and are therefore less likely to reflect societal needs, being driven instead by individual interests of actors and day-to-day decisions on land use (Idt and Pellegrino, 2021). The lack of a planning framework and municipal intervention might lead to unwanted side effects such as overcrowding or congestion (Dunning et al., 2020), as well as a high dependence on private landowners, leading to an effectiveness conflict (Puustinen et al., 2022). As a result, suburban densification is occurring, but it is primarily driven by individual interests and decisions rather than being strategically planned towards development goals or societal needs.

Municipalities face many challenges trying to pursue densification in line with societal needs and sustainable development. A constraint of municipalities lies in the lack of financial or personnel resources that make it impossible for them to cope with the labour-intensive challenges of densification (Eichhorn et al., 2024b). Moreover, the implementation of densification is strongly influenced by market conditions, including local housing demand and the strategic behaviour of market actors. Depending on the municipalities densification policy (Touati-Morel, 2015), they might rely on public–private partnerships with developers to implement projects. In practice, this can develop into a power asymmetry in favour of developers, overpowering municipal ideas for density and prioritising profit-oriented outcomes (Debrunner, 2024; Debrunner and Kaufmann, 2023; Eichhorn et al., 2024b). The possible negative consequences of profit-driven densification are extensively researched, highlighting that densification might come along with the displacement and exclusion of lower-income households (Debrunner et al., 2024; Götze et al., 2024) or even greater inequalities in the distribution of residential space (Bibby et al., 2021). Part of this is captured in the concept of the Business of Densification, where municipalities rely on developers to implement densification, often prioritising economic and ecological goals while largely neglecting social housing needs (Debrunner, 2024).

Another challenge lies in dealing with the landowners and residents on site. The high number of individual private landowners in suburban areas pose a particular challenge for municipal densification efforts, with many struggling to intervene in the already built environment and private property rights (Dembski et al., 2020; Gerber et al., 2018). Additionally, municipalities often face significant local resistance when pursuing densification. This resistance is particularly strong in suburban areas and rural areas, where residents tend to resist densification in their own neighbourhood despite generally accepting it elsewhere (Wicki and Kaufmann, 2022). Such resistance is often driven by landowners’ and residents’ fear of losing their familiar structural and social environment, leading to a fundamental rejection of growth policies (Touati-Morel, 2015; Wicki and Kaufmann, 2022). The resistance to densification is often fuelled by anti-growth tendencies in smaller municipalities that want to maintain their suburban or rural character (Touati-Morel, 2015).

The challenges of densification policies are exacerbated in the politically sensitive suburban areas, where density not only represents an urban structure but also reveals power relations of advantage and disadvantage. Choosing suburban living spaces and suburban ways of living are often an expression of the desire of residents for a sociocultural and demographically homogeneous composition of the neighbourhood (Fava, 1956). This also includes a desire for a separation from other social groups, often leading to the perception of suburban areas as socially homogeneous and stable spaces (Charmes and Keil, 2015; Frank, 2018). The combination of a lack of a planning framework and the dominance of landowners reduces the transparency and quality of densification processes, leading to a procedural justice conflict (Puustinen et al., 2022). With the density of suburban areas also being an expression of the social class and power of their residents and the lack of equal planning frameworks and actions, it is particularly difficult to intervene in suburban areas and get local support for developments and municipal intervention.

Because of the normative aspect of strategies, municipalities’ densification policies are also influenced by political interests and actors who may wish to protect the interests of particular residents. This may lead to difficulties with a dominant role of politicians in the process of negotiating density, compromising on densification in town centres ‘in exchange for the preservation of the status quo in residential neighbourhoods situated on large parcels of land’ (Rousseau, 2015: 626). Particularly in the context of wealthy suburbs, the political interests and targeted preferences of residents and their influence on politicians play an important role that needs to be considered (Charmes, 2009; Charmes et al., 2021). Looking at the politics of suburban communities, Fischel (2015) assumes that the above-average representation of homeowners in local elections and local representation ensures that the interests of owner-occupiers will prevail, resulting in the maintenance of suburban neighbourhoods. With the strategies municipalities employ to approach the implementation of densification, they make normative decisions about how much and in which cases to intervene in the built environment and private property rights – and in which cases not to intervene.

Planning law and instruments in Germany

Reducing land take has been an essential concern in the German discussion on sustainable environmental development, with its legal basis established through the amendment of the Building Code in 1987. However, it was not until the early 2010s that densification was formally defined as a key measure to address sustainable urban development. The first paragraph of the German planning law outlines the scope, definition and principles of land use planning. Specifically, Paragraph 1 (5) BauGB establishes that land use plans must promote sustainable urban development and socially just land use (Baugesetzbuch–BauGB, n.d.). ‘For this, urban development should primarily be carried out with measures of inner urban development’ (§1 (5) III BauGB, translated by the author). §1a (2) BauGB reinforces this by mandating municipalities to prioritise urban infill development and to assess the viability of densification prior to considering the use of undeveloped land. Based on this, municipalities must carefully consider strategies to promote densification to achieve sustainable urban growth.

In response to the housing crisis, legislators have recognised the challenges municipalities face in promoting inner urban development and are supporting their efforts with legal amendments to the planning law and its instruments (Hengstermann and Hartmann, 2021; Hengstermann and Skala, 2023). Changes included, among others, simplifying and accelerating processes such as drawing up a binding land use plan (§13a BauGB) or strengthening the municipalities position in the use of instruments such as the use of pre-emption rights (§ § 24, 25 BauGB). With this, the amendments aim to enhance municipalities’ ability to mobilise land and promote inner urban development more efficiently. Additionally, municipalities have a variety of possibilities to promote densification. While the most used instruments include development contracts and temporarily purchasing building land (Eichhorn et al., 2024a), more intervening instruments are available and discussed in the literature but less used in practice. These include, among others, land readjustment (Kötter, 2018), a vacant land tax (Löhr, 2023; Roboger, 2023), building obligations (Kolocek, 2018; Kolocek and Hengstermann, 2020) and compulsory property acquisition (Albrecht, 2018).

Despite the possibilities, municipalities frequently address housing demands through greenfield development and lower-density housing projects (Eichhorn et al., 2024b). With the limited implementation of densification, there are calls to offer municipalities more possibilities with new instruments. The reliance on changing planning instruments as an initial response has been critically described as instrumental activism, often falling short of achieving the intended outcomes (Hartmann et al., 2023). Despite legislative efforts to improve planning tools, their application has yet to yield the desired impact of increasing housing supply through densification. Municipalities continue to face significant barriers in leveraging these possibilities, and greenfield development remains the default solution for many urban planning challenges.

Methods

This study employed a qualitative research design, using problem-centred interviews with municipal employees to understand their interest and agency in suburban densification. Problem-centred interviews were chosen to gain insights into procedural and interpretative knowledge of experts (Döringer, 2021; Witzel, 2000). More specifically, the interviews allow for insights into processes and decisions, underlying motivations as well as power relations that might shape developments they want to promote and the possibilities they have and use to densify suburban areas.

The interviews were conducted in two areas in Germany: the Ruhr Agglomeration and the Frankfurt Rhine–Main Region, which both have undergone significant suburbanisation processes in the past and are now characterised by extensive suburban areas (Burdack and Hesse, 2007; Dembski et al., 2021). With previous literature highlighting the importance of resources and affluence of both the municipality and landowners (Charmes et al., 2021; Dembski et al., 2021; Eichhorn et al., 2024b; Rousseau, 2015) as well as the size of the municipality for their interests and strategies in densification (Eichhorn et al., 2024a; Touati-Morel, 2015), the municipalities were chosen to provide a nuanced understanding of the challenges associated with suburban densification in different local contexts.

The two studied areas are affected by contrasting economic situations. While the Frankfurt Rhine–Main Region is considered one of the most economically important regions in Germany, the Ruhr Agglomeration has been facing challenges related to a significant economic restructuring. While most parts of the region were able to overcome their dependence on steel industries with a new economic focus, the challenges of the past have had a significant impact on the current situation of the region (Initiativkreis Europäische Metropolregionen in Deutschland (IKM), 2024). Within each of these regions, interviews were conducted with one large municipality and at least one smaller municipality to highlight different situations and personnel resources. Overall, interviews were conducted in six municipalities, two of them from the Ruhr Agglomeration and four from the Rhine–Main Region.

The municipalities that were interviewed were chosen based on their self-selection, with 65 municipalities being initially contacted via email and six ultimately agreeing to participate. Between June and October of 2023, a total of 16 interviews were conducted across the six municipalities. The process began with interviews with a leading person in the planning department of each municipality, followed by snowball sampling to identify additional interviewees working on the topic of densification in the municipality. This approach allowed for interviews to be conducted with municipal employees from different departments and with different focuses, such as urban planning and development, land management, housing and property management.

The interviews were conducted using a semi-structured interview guide that focused on the practical experiences of municipal employees with suburban densification and their interactions with other actors. The interviews started off with an open-ended question about the municipality’s approach to suburban densification and the interviewees’ experiences and involvement in it, allowing the interviewees to share their perspectives and set a focus for the interview. Additional questions based on the guideline included organisational processes, challenges and opportunities they encountered in the implementation of projects and the instruments and strategies they used or considered in the processes. The interviews also highlighted the involved actors and their relations to one another, asking the experts about their perception of key actors and power relations in the process. Specifically, the interviewees were asked about their experience with suburban landowners, how they approached and engaged with them during processes, and the outcomes of these interactions.

The interviews were recorded and later transcribed. The interviews were conducted in German, with selected quotes translated by the author. The transcripts of interviews were analysed using a structuring qualitative content analysis based on Kuckartz and Rädiker (2023), using MaxQDA software. The coding process involved an initial coding framework derived from the interview guide, which was then inductively revised based on the data. The refined coding framework highlights three main categories discussed in the findings: organisational barriers, reflecting on challenges planners face within the municipal organisation, and influencing their interest in suburban densification; examining the instruments and strategies planners employ for suburban densification, revealing a surprising degree of flexibility in their approaches; and lastly, looking at the power landowners and local politicians have in shaping densification processes and outcomes, influencing planners’ possibility to implement suburban densification and the political influence of landowners and local politicians.

Results: Diversity of planners’ interest and agency in suburban densification

Organisational barriers to agenda setting in planning

The interviews highlight organisational challenges within municipalities as a hurdle to densification efforts. These challenges include the difficulty of prioritising densification on the municipal agenda, as well as the complex implementation of densification as an issue that requires coordination among various municipal departments.

What role does densification play for the municipality? My perception is that it plays a subordinate role. […] Instead, the strategy in recent years has been, and still is, to designate really large new building areas where a really large number of housing units can be accommodated. (Planning department, large municipality, Ruhr agglomeration; authors’ translation from German)

Although densification has been set as a goal for spatial development for a long time, the interviews highlighted that not all municipalities are interested in promoting suburban densification. Some municipalities do not set densification as a current priority, since housing demand is so overwhelming that they are focusing on creating as much housing as possible in as little time as possible. In these cases, achieving high numbers of new housing units is prioritised over reducing land uptake. These planners also referred to suburban areas as a great quality of the city, attracting preferred groups of residents. As a result, some municipal employees explained that they would not even want to densify or intervene in suburban areas and cannot imagine setting it as a goal for urban development.

In contrast to this, planners of other municipalities considered densification projects to be just another day-to-day task. In these cases, they highlighted suburban areas as areas with great potential for densification projects. Overall, municipalities prioritise densification very differently on their local agenda, especially in suburban areas.

We are working somewhat contrary to the demand on the market, because we believe that you simply can’t do that anymore. No, you can no longer realise a traditional owner-occupier residential area. (Planning department, small municipality, Ruhr agglomeration; authors’ translation from German)

The effort put into implementing densification did not seem to relate to the size of the municipality or the economic situation. In the analysed cases, suburban densification was not pursued more in larger municipalities than in smaller ones and not pursued more in financially stronger than in financially weaker municipalities. Instead, efforts to densify suburban areas appeared to be more related to the attitudes and perception of planning employees.

The interviews revealed difficulties in coordinating municipal departments, mainly affecting larger municipalities. In one case, a dedicated team was established to improve communication and comprehensive planning with the involvement of relevant departments, addressing shortcomings identified in previous densification projects. Despite these efforts, persistent communication issues remained, with other departments interviewed being unaware of the team’s efforts. Similar issues were found in the other large municipality, with departments contradicting each other on suburban densification efforts. The interviews underscore the unbridged gap in cooperation and responsibilities, which is crucial for handling overarching topics like densification in larger municipalities.

Promoting densification with flexible approaches

Municipalities pursued very different strategies for densification in suburban areas. In many cases, planners explained that a flexible handling of planning law is necessary to facilitate densification projects. Developers play a significant role in these efforts, with their influence varying from one municipality to another.

Several planners emphasised that planning law is made for the expansion of cities and is therefore making it much easier for planners to designate new building land on the outskirts rather than densifying the built environment. Some municipal employees stress that the planning law does not provide possibilities of intervening in already built-up areas and therefore identify it as a hurdle to densification efforts. Accordingly, they identify a lack of instruments as one reason for not approaching and implementing densification policies in suburban areas. Other interviewees also assume the same starting point of planning law enabling greenfield development, but take the same argument as an opportunity to experiment with a given planning law and question the common practice of interpretation of the planning law. While the analysed municipalities generally relied on the same instruments for densification efforts, the detailed application varied between them.

We are very … generous when it comes to exemptions from the land use plan, let’s put it that way. I am not in a position to judge whether this is all correct. (Planning department, large municipality, Rhine–Main-Region; authors’ translation from German)

Municipalities that try to steer densification found ways to deal with the given situation of land use planning. In the Rhine–Main-Region, several planners highlighted the common practice of a very generous interpretation of planning law in order to make densification projects possible or to speed up the process. In one municipality, a planner described a situation where his municipality was largely covered by binding land use plans and it therefore became normal to make a lot of exemptions from these land use plans to enable densification. In another case, a planner described a contrary situation with almost no binding land use plans in suburban areas. According to German planning law, in these cases the permissibility of a project is to be assessed based on the surroundings, for example in terms of storeys of the existing buildings. The planner explained that in his municipality, they encourage developers to deviate from the regulations, such as allowing additional storeys beyond the surrounding buildings, to facilitate densification. In the given examples where municipalities densified suburban areas, the planners showed a surprising amount of flexibility in the interpretation and handling of planning law, which is otherwise rather uncommon in the German context.

On top of the flexibility with planning law, planners tried different approaches to implement densification projects in suburban areas. One planner in the Ruhr Agglomeration explained how he set up a meeting with private property owners to discuss the possibility of densifying their gardens. While at first, he was met with a lot of anger and did not perceive the meeting as a success, the municipality managed to implement a densifying project on half of the gardens. In another case a municipality used a land readjustment to implement a plan that was designating a part of private gardens for a new road that would make the densification of the area possible. Again, the process proved to be very difficult, and resulted in a lawsuit for the municipality. Still in the end, the land readjustment was carried out and the area densified. While these cases were only partly successful, they are able to show the willingness of some municipal employees to experiment with instruments and approaches if they want to pursue suburban densification. On the other hand, they also show some of the difficulties and hurdles that municipalities have with the given instruments when using them for suburban densification.

My subjective experience is that when the investor comes with his idea, he wants to build 400 residential units. When he does the design, there are 800 on it. And then 1200 are built. That may be a bit of an exaggeration, but that’s how I’ve always experienced the process over many, many years. (Planning department, large municipality, Ruhr Agglomeration; authors’ translation from German)

With many municipalities relying on public–private-partnerships for densification projects, interviewees consistently pointed out developers as the main driver in densification processes, in urban as well as in suburban areas. However, the municipalities differed from each other in the extent to which they interact with developers and how much they try to influence the developers’ activities. Some local authorities do not try to intervene and accept the dominant position of developers, often leading to a higher density than desired. Other municipalities are making efforts to work closer together with developers to try and influence the developments. Some planners explained that they rely on cooperation with developers to take part in developing their city and therefore stay in close contact with local developers. Although German law prohibits linking the approval of a building permit to any payment or service from a landowner, a planner noted that developers often voluntarily commit to providing certain benefits or services to the municipality to maintain good relations with local authorities. In these cases, planners perceived developers as both good landowners and cooperation partners. Overall, municipalities varied greatly in how they dealt with developers as drivers of densification projects.

Political influence of landowners

Landowners and their reaction to densification were consistently highlighted as one of the main deciding factors of the success of implementing a project. One planner explained how they want to promote densification, but would only do it under the disguise of other projects in fear of triggering a political debate. The interviews highlighted the significant role of landowners’ reactions to densification projects and their influence on municipal approaches to the issue.

The influence of residents on politics and political decisions is greater than you might think. It has to be said quite clearly. There are no factual, professional or technical reasons that would rule this [densification project] out. […] Nothing that would prevent housing. No, it’s just the relationship between voters and elected officials. (Planning department, small municipality, Ruhr Agglomeration; authors’ translation from German)

The resistance from landowners or influential individuals is repeatedly emphasised as an important factor that determines the implementation and success of a densification project. Yet while the interviews highlighted the significance of this influence, it was rarely about legal disputes or protection of private property rights. Instead, planners mainly talked about how projects were more likely to fail due to the political abandonment of the project. Some planners describe how the resistance quickly leads to the involvement of local politicians, who in turn are able to influence the municipal practice. In one municipality in particular, a planner was desperate when he talked about a project in which it was neither legal nor technical reasons that stood in the way of implementation, but rather just the relationship between voters and elected officials that led to the abandonment of a project. This highlights how the resistance is not only based on the legal sphere of private property rights, but rather is significant because of the strong influence landowners or other powerful residents have on the municipality and local politicians.

But then you always have to think about it: Where is the interest here, what motivation is being pursued [by local politicians]? Is this really the Leipzig Charter, is this the 15-minute city? Or is it about allowing the third cousin to make more use of the plot so that he gets 300,000 euros more when he sells it? Identifying the motives and interests behind such efforts and then dealing with them is an everyday struggle. (Planning department, small municipality, Rhine–Main-Region; authors’ translation from German)

Many of the planners interviewed perceive local politicians rather negatively. They feel that politicians’ interests are not transparent and tend to favour private rather than public interests. Additionally, planners expressed that local politicians lack understanding of the problems of creating housing and reducing land uptake. One planner expressed that only a generational change in the key political positions could bring about a change. The interviews highlight a deeply strained relationship between planners and local politicians.

Discussion

Planners’ interest in suburban densification

The findings of this contribution highlight the interest and agency of planners when navigating suburban densification efforts. The findings highlight that the implementation of suburban densification is hindered by many challenges, starting with the willingness of some municipalities to pursue the goal as an initial difficulty. Some planners fundamentally reject suburban densification as a development goal for their municipality, mainly because they want to keep attracting their preferred high-income residents (Götze and Hartmann, 2021). Others prioritised quantitative housing developed over qualitative targets of densification or reducing land uptake. While anti-growth attitudes are regularly associated to suburban landowners or residents (Wicki and Kaufmann, 2022), the findings indicate that in some cases, the planner’s interests align with those of resisting landowners.

The findings have significant implications for the implementation of suburban densification. Amendments to the planning law to strengthen existing instruments, as they were regularly pursued in current amendments (Hengstermann and Hartmann, 2021; Hengstermann and Skala, 2023), will not be able to promote densification, when municipalities have no interest in prioritising the goal. This is in line with the call to stop instrumental activism and instead get a deeper understanding of local institutional context surrounding strategies and instruments (Hartmann et al., 2023). This highlights the need for a better understanding of the processes and actors’ interests to support the process of suburban densification efficiently.

Planners’ agency in suburban densification

While larger municipalities are shown to use more instruments when approaching net zero land take (Eichhorn et al., 2024a) and a lack of resources is highlighted as a significant hurdle to densification, the findings of this study show that some smaller municipalities with low financial and personnel resources were still able to demonstrate significant effort in promoting suburban densification. In line with other studies, the findings do not show a great variation in the formal instruments used by municipalities (Eichhorn et al., 2024b), yet the qualitative analysis shows that municipalities differ in how flexibly they use these instruments. Some municipalities actively aimed to be very flexible and pragmatic in their handling of planning law in order to make densification possible or speed up the process. This flexible approach reflects the idea that planners’ actions are shaped both by structural constraints and by their own motivations, values and knowledge (Filion, 2021). In line with Idt and Pellegrino (2021), the findings further show that the implementation of densification does not always strictly follow planning documents. Even when formal instruments or resources are limited, planners exercise discretion and creativity to navigate these constraints, illustrating how planners’ interest and agency are shaping densification outcomes.

In many cases, planners highlighted the strong push from developers for densification projects, aligning with the findings from other studies (Debrunner and Kaufmann, 2023; Eichhorn et al., 2024b). Some planners explicitly stated that they felt unable to effectively represent their interests against the powerful position of developers, highlighting the risk that public–private partnerships can tip into a situation of a strong power imbalance, a concern that is consistent with the findings of Eichhorn et al. (2024b) on the potential for power asymmetries in public–private partnerships. This can severely restrict planners’ ability to pursue development goals and interests, as they may be forced to compromise on key aspects of densification projects in order to secure developer investment.

A key influence on the success or failure of suburban densification was indeed identified in the landowners’ resistance to densification processes. However, the findings show that a significant part of the power of landowners stems from their political influence and their resources available rather than the legal sphere of private property rights. Planners instead talked about many cases where projects were abandoned due to landowners with significant political power and influence on local politicians. This finding is consistent with the explanation of the highly political nature of suburban densification and highlights the reluctance of politicians to intervene due to landowners’ political influence (Charmes et al., 2021; Fischel, 2015; Rousseau, 2015). The importance of resources and connections suggests legitimacy issues in the highly normative and powerful environment of suburban densification. Planners emphasise politicians’ incomprehensible interests and shifting attitudes in projects. This indicates a need for transparency of processes and information on who benefits from the densification or non-densification of an area. Future research should explore in more depth the positions of politicians and landowners and the power dynamics of these actors in processes of suburban densification.

Conclusion

This study employs a qualitative approach, consisting of problem-centred interviews with employees of municipal planning authorities on the interest and agency of planners navigating suburban densification. By exploring the experiences and perspectives of these actors, the findings are able to uncover unexpected insights into the factors that influence the success or failure of densification in suburban areas.

The findings indicate that suburban densification efforts are not necessarily failing, but are often simply not pursued or prioritised by municipalities. Some do not see it as a suitable development goal at all, while others prioritise different, competing objectives for spatial development. Additionally, some planners did not want to pursue it openly because of a fear of triggering a normative political debate involving landowners and politicians. The findings highlight that while landowners certainly have a powerful position due to their private property rights, the more relevant power of landowners comes with a political power due to resources and close connections to politicians. These power dynamics shape decision-making processes. Even when municipalities actively pursue densification, such dynamics can limit how effective these efforts are, raising concerns about legitimacy.

Contrary to a simplistic view of municipalities striving for densification and suburban residents rejecting change, this study gives a more nuanced picture. Instead of failing at the final stage of legally interfering with landowners’ private property rights, the investigated cases highlight how municipalities are mostly failing at hurdles much earlier in the process, already starting at the initial idea phase of interest to pursue suburban densification. However, some municipalities show pragmatic and flexible approaches to planning law to promote densification. Variability in municipal progress and strategies highlights the need for a nuanced understanding of the factors driving densification outcomes. In the municipalities analysed, the commitment does not appear to be related to the economic context or the size of the municipality, emphasising the importance of local efforts and approaches to implement densification.

The findings of this study have significant implications for the implementation of densification and reducing land take. The interviews were able to highlight how some planners struggle to coordinate conflicting demands, with densification in the suburbs often losing out. To promote densification, future policies should prioritise supporting municipalities in their efforts to densify, and provide them with the necessary resources and incentives to do so. The observed power relations of actors highlight the need to understand who might profit from densifying or not densifying and considering this in legitimate and transparent decision-making processes.

In conclusion, the study gives a better understanding of the local context in which planners work to implement suburban densification. The findings highlight that understanding the political and power dynamics at play as well as the hindering and enabling factors of suburban densification is crucial for developing effective interventions and strategies. While this research is able to highlight the planners’ perspective, there is a need to better understand the interests and agency of other involved actors, including politicians and private landowners. Future research is needed to explore potential tensions, legitimacy concerns and transparency issues arising from differing objectives and power dynamics. Overall, the insights from this research underscore the importance of reflecting on and understanding the interests and agency of all actors involved in suburban densification.