The process of gathering data for this study was guided by everyday practise of research K.M., the research question and the well-documented barriers that have been outlined in the literature. We compared our analysis and interpretation of the data to existing scientific models. Different theories such as Sectoral Collaboration (Bryson) (33), Intersectoral Action (Mondal) (34), Collaborative Governance model (Ansell and Gash) (35) and Integrative Framework for Collaborative Governance (Emmerson) (36), have been viewed. The Collaborative Governance model works well for collaborations between individuals and departments of organizations who are in the early stages. Also, this model is based on a meta-analytical study of existing literature and 30 empirical case studies (35), which provides opportunities for learning within the field of public health. Collaborative governance refers to an explicit, formal strategy of incorporating stakeholders into multilateral and consensus-oriented decision-making processes. The four components of the collaborative governance model are the collaborative process, facilitative leadership, institutional design and starting conditions (35). Collaborative-process variables form the core of the model, which is presented as a cycle, given the highly iterative and nonlinear character of the process. The other components (i.e., attention to trust, power, resources and knowledge on the start of the collaboration process, institutional rules and available leadership) are important contributors to a supportive context within which the collaborative process takes place (35). Good collaboration within the municipality is important to the ability to communicate jointly and unambiguously with external stakeholders and inhabitants. Our study therefore starts by concentrating on collaboration within one municipality before examining collaboration between municipalities and other stakeholders.

In this qualitative study, we sought to identify similarities amongst municipalities regarding their experiences in collaboration across domains, along with potential perceived improvements. Semi-structured interviews were conducted with civil servants from different policy areas in five Dutch municipalities. This is an effective data-collection method for a detailed exploration of the views and experiences participants (37). The study was carried out in a collaboration between two consortia (Space2move and GELIJK) within the ‘Maak ruimte voor gezondheid 2018–2022’ (Make space for health) programme (38) operated by the Dutch funding organization ZonMw. This programme consisted of seven regional consortia of practitioners, policymakers and scientists each conducting a study on the effects of environmental planning on health, sustainable (un)healthy behavior, and participation in society. A part of the research conducted within this programme also focused on strengthening collaboration and implementation of a healthy living environments. The medical ethics committee for the Arnhem-Nijmegen area (2018–4252) and the ethics committee of Tilburg University (number RP211) approved this study, which was conducted according to the principles of the Declaration of Helsinki (October 2013, 64th WMA General Assembly) and in accordance with the Dutch Personal Data Protection Act. Written informed consent was obtained from all participants prior to data collection (Figure 1).

The selection of the five municipalities was with purposive sampling in a different cases design based on the involvement that the municipalities had with healthy living environments. The most important factor for inclusion was the municipality’s participation in the ZonMw ‘Make space for health’ programme (38). In addition, we asked municipalities that were involved in the Gelderland City Network, which focuses on collaboration and sustainability in relation to health and well-being. Five of the ten available municipalities ultimately decided to participate in this study.

The municipalities included in the study varied in terms of a wide range of demographic characteristics (e.g., number of inhabitants, urbanization, number of employees), and the participants differed according to position, gender and years of experience (Table 1).

Given our focus on collaboration between domains within municipalities, for the selection of the participants, we sought to incorporate a variety of civil servants from each participating municipality. More specifically, we selected a civil servant with a focus on health (social domain), one with a focus on the built environment (physical domain) and one who was tasked with implementing the Environment and Planning Act. The selection of interviewees was strategic. We started by reaching out to a point of contact in each municipality. This person was asked to personally approach three or four colleagues to participate. This resulted in a total of 21 participants, varying from three to five civil servants per municipality.

The data were collected between November 2019 and March 2020. The topic of collaboration between the social and physical domain in the Netherlands gains renewed interest and relevance with the introduction of the Environment and Planning Act in 2024. Some of the results in this article were confirmed in a more recent study (data collection sept- nov 2022), while other findings in this paper have not been countered in our later study data. Most of the interviews were held in person, but some had to be held through video-calling, due to the COVID-19 pandemic. The interviews were audio-recorded and transcribed verbatim. The duration of the interviews ranged from 60 to 90 min.

In addition to generating the data for this study, the interview guide used (Supplementary Appendix Table A1) led to an article on the spatial-planning process and the focus on health during this process (submitted). The interview consisted of the following parts: job description, integrated assessment processes, collaboration between the social and physical domains, health in spatial-planning projects, the Environment and Planning Act, and general information. The interview guide also included two simple instruments. The first instrument asked respondents to rank (in order from most to least experience) a list of obstacles known from the literature (17–20): different problem definitions, conflicting interests, differences in language and culture, lack of mutual understanding, and differences in short-term and long-term vision. The second instrument was used to identify the extent to which the municipalities paid attention to health in spatial developments. We used the maturity model developed by Storm and colleagues, which consists of five stages: unrecognized, recognized, considered, implemented, integrated and institutionalized (39).

The main investigators of this study, the authors K. M. and H. S, recruited the participants and conducted the interviews. In addition, a third interviewer was employed by Radboud university medical center. This interviewer received instructions from K. M. with regard to data-collection and interview techniques.

The data were analyzed using the AtlasTi 8.1 software package. Transcripts were analyzed according to open coding (40, 41), starting from the main aspects of this study (e.g., current collaboration, definition of domains, enablers and challenging elements, personal attitude towards collaboration, personal experience with collaboration, aspects of institutional design, and ideas for improvement in collaboration). The ranking of obstacles to municipal collaboration (instrument 1) and the level of attention paid to health in spatial development (instrument 2) proved to be highly interrelated and have therefore been analyzed and processed in an integrated way. To establish inter-rater reliability, the authors K. M. and H. S. coded the first two transcripts separately, after which they compared and discussed the codes until consensus was reached. This process resulted in the codebook that was used by one author to code all other transcripts, and by the other author to checked these codes. In this step as well, differences were discussed until consensus was reached. In all, 27 codes of the 65 codes were used for this article. The other codes were used for another article (submitted). In the next step of the analysis, the data were examined separately for each domain, before the sets were put together.

The new Environment and Planning Act encourages civil servants to work together in both the social and physical domains. Nevertheless, concrete spatial-planning projects are regarded as the most important reason for collaboration. Such projects bring together civil servants from different policy areas, as coordination amongst these areas is required with regard to what needs to be achieved (e.g., specifications for layout, minimum area requirements or the possibility of combining diverse functions).

In recent years, all participants from all municipalities addressed in this study had experienced an increase in contacting each other, finding each other and initiating collaboration. At the same time, however, collaboration continues to occur on an ad hoc basis. It is highly dependent on how individual civil servants interpret their organizational task descriptions if the collaboration occurs. In most cases, it takes place within the specific domains of the individual civil servants. The participants noted that their experiences have been positive when seeking collaboration simply by reaching out to and starting to communicate with other parties. During this initial step, they get to know each other better and gain a higher level of comprehension, thereby enhancing their understanding of each other and their respective working methods. The aspects of communication emerging in this step (e.g., proactive thinking, talking with each other, transparency) and cross-pollination (as a means of building relationships and social capital) thus apparently provide a good foundation for collaboration.

According to the participants, collaboration depends in large part on the project or assignment. When the project description encourages collaboration between domains, other disciplines are often more actively and consciously involved, and overlapping themes are explored. One aspect that encourages collaboration is the designation of a project leader, who is charged with seeking common ground across disciplines. Another factor that participants mentioned as having a positive impact on their working attitudes towards collaboration occurs when aldermen advocate and promote structural collaboration across disciplines. Collaboration is facilitated by some specific themes (e.g., sports or local environment vision documents) in which common ground between the social and physical domains is clearly visible. Collaboration between domains is also encouraged by bottom-up approaches proceeding from the perspective and needs of neighborhood inhabitants.

As noted by the participants, the collaborating activities described above require hard work. One reason is that, in many cases, the social and physical domain continue to be perceived as two separate worlds, each with its own working attitudes, structures, knowledge base and task descriptions. The social domain is oriented towards people and the short-term enhancement of liveability, whereas the physical domain focuses on the built environment and the long-term enhancement of liveability. Time and practice is needed to overcome this perspective, together with a feeling of intrinsic motivation to take steps in favour of collaboration.

The participants mentioned several elements that influence collaboration, both positively and negatively. Although they are highly entangled, we used the four components of the Collaborative Governance Model developed by Ansell and Gash (Table 2, Columns 1 and 2) to structure these elements in order to enhance interpretation. Given our primary objective of identifying necessary improvements, the following text focuses largely on this issue, as presented in Column 3 of Table 2.

Complexity emerged in connection with many issues and topics that the participants reported addressing in their work. Although complexity in itself provides common ground between domains, it can also quickly become overwhelming, thereby generating even more complexity. To overcome this, it could be helpful for the municipal organization to have starting conditions that facilitate collaboration. For example, to overcome the complexity of social and health-related issues, the municipal council (consisting of the mayor and aldermen) and managers could demand integral approaches that lead to overarching programmes. In addition, a clear municipal vision, clearly expressed by all aldermen, resulting in joint assignments would have a positive influence. The participants further noted that these starting conditions subsequently provide incentives for collaboration, as they create a sense of empowerment by the organization. The incorporation of collaborative activities into job descriptions was also perceived as helping civil servants to focus on the overall vision of the municipality, instead of on their own tasks.

In the opinion of the participants, joint assignments could also help to address resource imbalances, as budgets currently tend to be organized from the top down, through separate programmes and departments, instead of horizontally, through overarching programmes or from the bottom up, in alignment with needs of the inhabitants. The neighborhood approach was mentioned as a helpful starting point, in which budgets are easier to merge or transfer.

In addition to the integrated organization of budgets, participants placed high value on bottom-up approaches proceeding from the needs of inhabitants within the community, as well as on area-focused projects, as they provide a similar starting point for both the social and the physical domain. This brings both domains together at the table directly from the beginning, resulting in a smooth stimulus for collaboration. It is also helpful to build on a positive history of collaboration, overcoming several gaps (as mentioned in Table 2, under ‘Prehistory of collaboration’).

Another element of starting conditions that participants mentioned was ‘lack of having the full picture’. This occurs when civil servants do not have sufficient knowledge of what is going on in the other domain in terms of projects and working processes. Although participants noted that this element could also be functional (by maintaining a focus on individual tasks and aims, instead of adding complexity), they also acknowledged their desire to have a more clear picture of what was going on in their organizations. Ideas for how this can be done included making use of visualizations (see Table 2).

According to the participants, resources at the provincial or national level can be used to support collaboration when seeking a broader perspective on how to improve a healthy environment. This can be accomplished through programmes aimed at collaboration, as well as through funds intended to stimulate collaboration. One disadvantage of this element has to do with the fixed amount of budgets, which neglect the amount of time that the collaborative process can take before the actual collaboration can start.

Every participant expressed willingness to collaborate and understand their own responsibility. During the interviews, participants were aware that collaboration is accompanied by individual effort in personal contact, thereby acknowledging their own influence on the process. They also reflected directly on their own shortcomings with regard to taking action in this regard. According to the participants, the collaborative process starts with having an open attitude towards each other’s expertise and working methods; genuinely listening to each other in order to truly understand what the other needs; ‘being able to translate needs to actions’, knowing where to start and proceeding from the assumption that others are available and willing to collaborate. Mastering these specific skills could be beneficial for the collaborative process, as it builds on mutual understanding and creates a good base for finding common ground.

During the interviews, participants acknowledged that short lines of communication are essential to remaining informed. One way to ensure this could be to build further on existing contact and to establish and deepen the connection, given the ongoing processes that collaboration entails. Another way could be to ‘simply’ initiate the contact, to get to know each other, to learn the work that each other does and to see common ground between disciplines. After the first contact has been made, especially when people see that someone is interested in their work, they are more likely to involve them in future projects. This builds on intrinsic motivation. Finally, participants mentioned that the organization of orientation meetings could be beneficial as well, or establishing connections with colleagues through the use of online communities (e.g., WhatsApp groups or the intranet).

Collaboration calls for long-term commitment and acknowledging that neither change nor collaboration occurs overnight. Civil servants need to be persistent in their involvement in the process, particularly in light of the possibility that contacts might leave again, causing to start the process of collaboration all over again. Furthermore, raising awareness of the importance of a healthy living environment is an ongoing effort. This means that it is important not to avoid discussions when conflicts arise, but to discuss them in a structural manner, keeping in mind the vision of the municipality and expectation management. Taken together, these observations point to the necessity of being committed to the collaborative process, which is continuous.

The long-term, continuous nature of collaboration raises the issue of time, in combination with tremendous work pressure and lack of capacity. According to participants, this has an enormous influence on collaboration. Investment in the process of collaboration requires making time to (1) come into contact, (2) get to know and understand each other, (3) find common ground between the living environment and health, and (4) get to know the working methods of each domain. Time was also mentioned in combination with the zeitgeist (spirit of the times). This refers to the time that it takes for people (from early adapters to late followers) to understand the meaning of collaboration and to develop a solid base for collaboration to jointly achieve the ambitions of the municipality. One positive experience in this regard was observed during the development process of the municipal vision document on environment and planning policy. To date, this process had devoted sufficient attention to time, prioritising themes and organising the vision in a collaborative manner. As mentioned by the participants, from the very beginning, time had been made for coming together, discussing opportunities and finding alignment in perspectives for this vision. In this example, the collaborative process is part of the work process involved in arriving at an overall environment and planning vision. In contrast, within other occasions contacts, the collaborative process is likely to be seen as an additional task added on top other existing tasks. Learning from this positive experience might help to improve collaboration in other occasions.

Problem definition and conflicts of interest were also identified as having an influence on the collaboration process, although not all participants had experienced the influence of these elements in their own work. Problem definition had influence when issues were approached only from people own perspective or from within a narrow view, thereby ignoring the full picture or allowing for the existence of different perspectives. According to the participants, problem definition can have a particularly heavy influence when a complex problem like health is not seen as an issue, nor the possibility that each domain has an influence on the pursuit of a healthier living environment. Within such contexts, conflicts of interest can arise as well. Aspects mentioned in this regard included the tension between organizational interests and personal interests, the neglect of the ambitions and vision of the municipality, and a focus on short-term as opposed to long-term solutions. Participants noted that there was room for improvement in several areas. One suggestion was to have regular dialog about the implementation of health-related preventive measurements in spatial-planning projects, keeping in mind the long-term effects of these measures. Another was to acknowledge that different people have different points of view, and that they are therefore likely to have different definitions of the problem. Another helpful suggestion could be to start from the same base (e.g., the inhabitants of an area; a mutual assignment). Further suggestions for improvement and details are listed in Table 2.

The institutional design influences collaboration within the organization. Analysis of the data revealed five levels of collaboration that are related to the institutional design and should therefore be considered in the institutional design. First, collaboration takes place at the individual, personal level, between individuals. Second, collaboration occurs between professions and positions, with regard to knowledge and expertise. Third, collaboration between domains takes place to create a more substantive dialog regarding themes, aims and assignments. A fourth level of collaboration is seen between different layers in the municipal organization. Finally, collaboration takes place between the municipal organization and external partners, both public and private. These levels were entangled, thus revealing the layered constitution of collaboration. Given the difference in levels of collaboration, it could be expected that different perspectives also exist concerning how participants understand collaboration as a concept and they experience it in practice.

According to the participants, the institutional design should stimulate collaboration organically. At present, each domain could be seen as a system as such, each with its own policy, processes and issues. This maintains the tendency to think in silos. Rather than drastically changing the organization or requiring the compulsory education of their colleagues, participants suggested changes in the framework of the organization.

One suggested change was to create teams or overarching programmes (in terms of both people and resources). One example could be a team living environment, which would immediately bring the two worlds together.

Such programmes and teams could also help to overcome the tendency to think in silos, as they work together from the start. This should be done in all layers of the organization, and it should start with clear communicative support and execution at all layers.

One influential element that could stimulate this change comprises culture and language. According to participants, this factor is interwoven throughout the organization, with asymmetries in language (e.g., definitions) and different cultures across domains. One initial step in overcoming this element could be to acknowledge that there are different types of people in each domain, each with a different background and different perspectives on the problem. Take a step away from the problem or issue at the table, and start by searching for similar definitions could help those involved to speak the same language. Participants noted that they should dare to dig deeper and find the root cause and meaning of what someone says until they truly understand what has been said.

Another suggested change had to do with making communication within the organization a more supportive system that could facilitate networking amongst civil servants, easing communicate and linking to each other. Some referred to this as ‘creating a network organization’. In this regard, the organization could also create a sense of unity — a feeling that ‘we’ are working together for the inhabitants. Participants identified this as a facilitating condition, stimulating collaboration that looks over imagined boundaries, even in the heat of the moment and at busy times, as it maintains the focus on the inhabitants. Most participants noted that this condition is not currently present. One structural change that had thus far generated good results in terms of finding each other more easily is to have everyone working in one building. This stimulated small talk through encounters in the corridors or coffee areas. It is also helping to downsize collaboration by allowing civil servants to experience the fact that collaboration starts with small steps.

Sustainable change in the organization can also be created by changing the name of the programme and assigning more in-depth meaning to particular words. This can result in fresh exposure to what is being done. Furthermore, participants suggested that more reflection on the results of policy and collaboration and sharing information about good practices or the process of involvement in a project could create positive experiences and results. This also points to new opportunities for building bridges across domains. If done in a suitable way, such reflection could become a starting position and a sustainable foundation from which to work, as it builds upon previous experience.

To overcome the tendency to think in silos, facilitator jobs could be created within the organization, with bridging the gaps between the social and physical domains included in the job description.

The creation of such positions was suggested by participants as a way to improve collaboration more organically. In their current experience, participants focus primarily on their daily tasks and the objectives of the own domains, and they continue to be held accountable within this narrow area. Moreover, many participants mentioned that they did not (or did not wish to) have a full picture of what is needed, and that they preferred to focus on their own tasks. The new facilitator should be able to look at the full picture, serve as a linking pin, have knowledge about both worlds (the social and physical domains) and possess expertise with both the content and the process of collaboration.

Participants expressed a desire for more support. In their opinion, such a supportive system could start with the aldermen and the managers (as mentioned under Starting Conditions). This could generate a structural, directive form of collaboration that emphasises the importance of collaboration.

In the interviews, civil servants also expressed a need for aldermen to dare to consider the long term and frame a clear vision of the municipality. This long-term character should extend beyond the term of the aldermen (in the Netherlands, four years). They should also show their support in both words and actions. This could be encouraged by modeling a joint vision and board assignments, which programme managers can translate to the executive teams. According to the participants, if the board and aldermen were to actively search for ties, the other layers in the organization will follow.

As mentioned under Institutional Design, facilitators should have leadership skills, in order to bridge the two domains at the executive level and to leverage between levels within the municipal arena. They should also be very straightforward and dare to say, “If you do not have them on board, nothing is going to happen.”

The most prominent strength of this study is that it was designed to identify concrete ways in which to enhance collaboration between the social and physical domains and to avoid becoming mired in the obstacles that prevent such collaboration from taking place. The findings of this study clearly reveal a significant level of willingness to establish collaboration. In addition, the results provide many starting points for municipalities. The suggested recommendations might have unintended and undesirable consequences such as the sharing of budgets implies. We recommend that this should be taken into account in the specific municipal context. Because this study is not quantitative the outcomes are not directly applicable to other municipalities. It also does not address disparities amongst municipalities. It would therefore be beneficial to conduct further investigation of similarities and differences through quantitative study in as many municipalities as possible.

Another limitation of this study is that it does not provide insight into the development of collaboration between the social and physical domains. Such insight might have provided interesting starting points for improving collaboration. In addition, the study focused solely on collaboration amongst civil servants from the social and physical domains, and it did not include any other parties involved in spatial-planning projects processes. The roles of aldermen, managers, external parties and inhabitants is also significant in these types of projects, and they can have a significant impact on collaboration and its outcomes.

Future studies could examine the perspectives, contributions and involvement of aldermen, managers, external parties and inhabitants in spatial-planning procedures, as well as the implications of their involvement in the process of collaboration between the social and physical domains. It would also be interesting to focus on specific elements of this collaboration, especially trust and power. Long-term research into the progress of collaboration could generate further knowledge about how such collaboration develops and which elements play more or less prominent role at a certain point. Another interesting area to follow up could concern the possible existence of a relationship of dependence between the physical domain and the social domain. Our findings do not provide a clear picture in this regard. It would therefore be interesting to conduct further investigation to obtain a more precise understanding of this topic.