Obstacles and Drivers of Sustainable Horizontal Logistics Collaboration: Analysis of Logistics Providers' Behaviour in Slovenia

Academic Editors: Manh-Hoang Do and Yung Fu Huang Received: 4 July 2025 Revised: 25 July 2025 Accepted: 30 July 2025 Published: 1 August 2025 Citation: Pentek, I.; Letnik, T. Obstacles and Drivers of Sustainable Horizontal Logistics Collaboration: Analysis of Logistics Providers’ Behaviour in Slovenia. Sustainability 2025,17, 7001. https://doi.org/ 10.3390/su17157001 Copyright: © 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/ licenses/by/4.0/). Article Obstacles and Drivers of Sustainable Horizontal Logistics Collaboration: Analysis of Logistics Providers’ Behaviour in Slovenia Ines Pentek and Tomislav Letnik * Faculty of Civil Engineering, Transportation Engineering and Architecture, University of Maribor, Smetanova Ulica 17, 2000 Maribor, Slovenia; [email protected] *Correspondence: tomislav[email protected] Abstract The logistics industry faces challenges from evolving consumer expectations, technological advances, sustainability demands, and market disruptions. Logistics collaboration is in theory perceived as one of the most promising solutions to solve these issues, but here are still a lot of challenges that needs to be better understood and addressed. While vertical collaboration among supply chain actors is well advanced, horizontal collaboration among competing service providers remains under-explored. This study developed a novel methodology based on the COM-B behaviour-change framework to better understand the main challenges, opportunities, capabilities and drivers that would motivate competing companies to exploit the potential of horizontal logistics collaboration. A survey was designed and conducted among 71 logistics service providers in Slovenia, chosen for its fragmented market and low willingness to collaborate. Statistical analysis reveals cost reduction (M = 4.21/5) and improved vehicle utilization (M = 4.29/5) as the primary motivators. On the other hand, maintaining company reputation (M = 4.64/5), fair resource sharing (M = 4.20/5), and transparency of logistics processes (M = 4.17/5) all persist as key enabling conditions. These findings underscore the pivotal role of behavioural drivers and suggest strategies that combine economic incentives with targeted trust-building measures. Future research should employ experimental designs in diverse national contexts and integrate vertical–horizontal approaches to validate causal pathways and advance theory. Keywords: COM-B framework; operational challenges; behaviour change; trust barriers; strategic opportunities 1. Introduction The logistics industry is undergoing a period of intense transformation, driven by increasingly complex and unpredictable global supply chains. Logistics operators are confronted with challenges that require rapid adaptation and resilience in their operations. Recent events, such as the COVID-19 pandemic, the Suez Canal blockage, and extreme weather conditions, have exposed vulnerabilities in existing systems and demonstrated the need for more robust and flexible logistics solutions [1]. A critical aspect of building resilience lies in the logistics infrastructure itself, which serves as the backbone of supply chain operations. Current infrastructure predominantly relies on high-capacity transport corridors prioritizing economic efficiency. Although this model is effective under normal circumstances, it proves highly vulnerable during disruptions due to a lack of alternative routes or sufficient contingency measures [ 2 ]. Long-term Sustainability 2025,17, 7001 https://doi.org/10.3390/su17157001 Sustainability 2025,17, 7001 2 of 30 upgrades to physical infrastructure remain essential to address these vulnerabilities, but these upgrades often require big investment and take a lot of time. In the short to medium term, it is therefore essential for companies to explore alternative and complementary improvements. One promising approach is to adopt its capacities and optimize existing logistics resources [ 3 , 4 ]. Studies consistently reveal that freight vehicles are frequently under-utilized [ 5 ], exhibiting high rates of empty runs and low-load factors, especially in last-mile transport [ 6 ]. These inefficiencies not only exacerbate traffic congestion but also significantly contribute to environmental pollution, placing freight transport among the largest emitters of greenhouse gases [ 7 ]. Addressing these challenges requires innovative business models promoting resource sharing, collaboration, and sustainability [8,9]. Optimization strategies can be implemented into various logistics aspects related to existing challenges of logistics operators. One of the most pressing issues is how to alleviate human resource-related constraints. R. M. da Silva et al. argue that persistent labour shortages and high staff turnover rates disrupt operations, reduce service reliability, and increase recruitment and training costs [ 10 , 11 ]. Furthermore, economic and market-related challenges such as unfair competition, high energy costs, and payment indiscipline [12–14] significantly strain logistics companies, leading to financial instability and reduced competitiveness. Another critical area requiring attention is the integration and coordination challenges within the logistics sector. Fragmented customer demands and limited integration among logistics providers contribute to inefficiencies, redundant capacities, and compromised service quality [ 6 ]. Urban logistics operations further face substantial infrastructural and regulatory constraints, including inadequate urban infrastructure [ 15 ], restricted access regulations (e.g., Urban Vehicle Access Regulations—UVARs) [ 16 ], and stringent compliance demands related to environmental standards like Euro norms and ESG reporting [ 17 ]. In additions, logistics companies face significant challenges in shifting toward environmentally sustainable logistics solutions, particularly due to high upfront investment requirements, technological limitations, and complex regulatory frameworks [ 18 ]. Lastly, technological and knowledge gaps pose notable challenges. Badraoui et al. and others argue that insufficient data availability, limited digitalization, and inadequate knowledge of advanced optimization techniques and IT system integration prevent logistics companies from fully leveraging technological advancements [19,20]. In addressing these various challenges, horizontal logistics collaboration (HLC) emerges as a particularly promising solution. Numerous empirical and conceptual studies emphasize that HLC can enhance vehicle utilization, reduce operational costs, decrease delivery mileage, and improve service flexibility [ 14 , 21 , 22 ]. It also contributes to lower fuel consumption and fewer empty runs, resulting in more efficient use of transport capacity and reduced congestion. These benefits are particularly relevant for small and mediumsized logistics enterprises (SMEs), which often face limitations in resources, capacity, and market reach. For these firms, collaboration represents not just an opportunity but a necessity. As highlighted by Simmer et al., cooperation will become increasingly important for SMEs in a competitive and technologically advancing logistics environment [ 23 ]. Jesica de Arma and others [ 24 ] similarly argue that SMEs must pool resources and expertise to remain viable and competitive. In this way, HLC enables them to expand their service offer, access new markets, and improve operational resilience. Basso et al. and Wang and Kopfer also emphasize that SMEs benefit most from HLC, as they are less able to achieve economies of scale on their own [ 25 , 26 ]. Beyond operational gains, HLC also offers strategic benefits, including improved competitive positioning, increased adaptability to regulatory changes, and reduced environmental impacts [ 20 , 27 ]. These advantages are particularly relevant in the context of rising customer expectations and growing pressure to decarbonize logistics operations. Shared resources such as warehouses, vehicles, and IT Sustainability 2025,17, 7001 3 of 30 systems facilitate economies of scale and help companies meet growing customer demands for reliability, speed, and transparency [ 27 ]. Moreover, collaboration enables even smaller firms to access infrastructure and service capabilities that would otherwise be financially out of reach, fostering greater inclusivity and resilience within the logistics sector. However, despite its recognized potential, implementing horizontal logistics collaboration (HLC) presents significant challenges. A major barrier frequently highlighted in the literature is the lack of clear rules concerning the responsibilities, rights, and fair distribution of resources, costs, and revenues among partners [ 19 , 20 , 28 ]. Additionally, transparency issues and distrust, particularly among competitors, complicate effective cooperation [ 19 , 20 , 29 ]. Studies also find that identified suitable partners with aligned strategic objectives and logistics processes also poses substantial difficulties, as misalignment can hold back collaborative efficiency [ 19 , 20 , 29 ]. In addition, challenges such as maintaining long-term commitment, managing power imbalances between partners, concerns over preserving autonomy, cybersecurity risks, and IT system integration further complicate implementation [ 19 , 20 , 27 ]. Furthermore, reluctance to share necessary data and difficulties with the acquisition, exchange, and management of essential information due to inadequate communication technologies intensify these issues [ 19 , 22 , 28 , 30 ]. Finding a trustworthy independent third-party facilitator capable of coordinating collaboration is another critical yet challenging aspect [ 20 , 29 ]. Barraoui, Andersson and others also found that ineffective organizational structures, complexities involved in optimizing joint logistics processes, legislative restrictions, resistance to necessary organizational changes, and limited awareness of collaboration benefits further hinder successful implementation [ 19 , 28 , 30 ]. Addressing these complex challenges is essential for realizing the full potential of HLC. While these potentials and challenges are widely discussed in the literature, some very important gaps remain inadequately addressed. Many existing studies rely on case studies, expert interviews, or macro-level analyses, yet relatively few directly engage logistics service providers (LSPs) to examine the specific barriers, incentives, and conditions influencing their willingness to collaborate. For instance, Schachenhofer and others identified opportunities and obstacles for urban logistics collaboration, to better use the underutilized urban logistics infrastructure, but they notably excluded logistics companies from the participant pool [ 14 ]. Zhang and others investigated collaboration among LSPs in China but gave limited weight to LSPs in their participant sample (only 39.1%) and did not address the dynamics in micro-enterprise-dominated markets [ 31 ]. Another study compared expectations of non-collaborative and collaborative professionals, yet without considering how company size shapes willingness to collaborate [ 19 ]. Simmer et al. examined beliefs and motivations for collaboration around the Physical Internet using a small sample of Austrian transport providers but did not differentiate based on collaboration experience and company size [ 23 ]. Sternberg and others analysed failure cases of systematic collaboration but included only companies with prior collaboration experience, omitting non-collaborative sample [ 32 ]. Similarly, Albers and Klaas-Wissing explored less-than-truckload (LTL) alliances through two contrasting cases, yet the narrow scope of research limited broader generalization [33]. In summary, these studies offer valuable insights but fail to fully address the challenges and opportunities of HLC within highly competitive logistics environments where SMEs predominate, particularly when comparing collaborative versus non-collaborative firms. There is also a lack of studies that systematically compare motivations, barriers and especially the readiness for collaboration based on company size and previous collaboration experience. This gap is especially relevant in regions where cooperation is not the norm and where resource limitations, trust issues, and operational pressures intensify resistance to change. Sustainability 2025,17, 7001 4 of 30 This article directly addresses these gaps. Firstly, it synthesizes recent findings on the benefits, obstacles, and behavioural drivers of HLC, with a specific focus on underrepresented micro and small enterprises. Secondly, it employs a tailored COM-B-informed survey [ 34 ] to collect empirical data from 71 logistics companies in Slovenia [ 35 ], where the logistics market is defined by strong competition, high fragmentation, and low collaboration maturity. The survey design captures both collaborative and non-collaborative firms, and links operational challenges, motivational drivers, and collaboration readiness with company-specific characteristics, including size, service profile, client types, transport intensity, fleet structure, and storage capacity. This enables a multidimensional comparison across firm types and collaboration experience levels. Finaly, the article proposes managerial and policy measures, including neutral data-trust platforms, transparent costand carbon-sharing rules, and targeted behavioural incentives [ 19 , 33 ] to facilitate the transition from short-term pilot projects to sustainable, multi-partner networks. By integrating comprehensive evidence with new empirical insights, this study enhances the understanding of HLC, particularly within environments where collaboration is both critically challenging and necessary and provides concrete recommendations for practitioners and policymakers. 2. Materials and Methods This section outlines the methodological approach taken to investigate the dynamics of horizontal logistics collaboration. Building on the challenges and gaps identified in the introduction, the methodology is designed to explore key factors influencing collaborative readiness, motivations, and barriers among logistics companies. This study examines horizontal collaboration among logistics providers, including smaller firms offering only specific transport and/or warehousing services. It excludes companies that are ordering logistics services, since those interactions fall under vertical collaboration. The research focuses on Slovenia, selected for its unique logistics, economic, and cultural characteristics, which make it particularly suitable for studying the challenges and opportunities of HLC. Over 75% of logistics service providers and companies in Slovenia are micro and small enterprises, constituting a significant portion of the sector and making collaboration essential for maintaining competitiveness in a fragmented market [ 35 ]. The country’s strategic location at the crossroads of major European transport corridors, including the Baltic–Adriatic, Mediterranean and Western Balkan–Eastern Mediterranean core corridor, presents unique logistics challenges and opportunities for regional and international trade. Slovenia’s Logistics Performance Index (LPI) score of 3.3 in 2023—above the global average of 2.87—further underscores its relevance as a case study, reflecting its solid infrastructure and logistical capabilities [36]. Additionally, Slovenia’s cultural and organizational factors present distinctive dynamics for collaboration. A high score of 81 on the Individualism index suggests a preference for independent decision-making and informal and weakly structured social framework, which can hinder collaboration without strong incentives and structured agreements [ 37 ]. This individualistic tendency, coupled with the dominance of small enterprises, necessitates targeted strategies to foster trust and alignment among stakeholders. Furthermore, Slovenia’s established regulatory framework, combined with its relatively small but accessible logistics market, allows for comprehensive data collection and in-depth analysis of collaboration readiness and barriers. Together, these attributes highlight Slovenia as an exemplary context for exploring HLC. To gather data, we designed a structured online survey (available in Supplementary Materials) using a web-based tool. Our approach is based on the COM-B behaviour framework, which considers the complex interaction of capability, opportunity and motivation. It serves as our theoretical foundation for understanding behavioural aspects of HLC. Sustainability 2025,17, 7001 5 of 30 Conceptually, capability is a company’s physical and psychological capacity to collaborate. It includes skills, knowledge and access to necessary resources. Opportunity refers to external influences that enable or hinder collaboration. These influences include infrastructural conditions, organizational norms and market structures. Motivation represents the internal processes that drive firms to pursue and sustain collaborative partnerships. These processes include reflective intentions and drivers. They are shaped by expected benefits, social expectations and strategic priorities. To capture both capability and opportunity, we first addressed operational challenges. These included, for example, labour shortages, high energy costs and underutilization of freight capacity. Respondents rated how these issues affect their work and logistics processes. We then explored past collaboration experiences and barriers. Building on these foundations, we examined a full spectrum of collaborative forms, from informal agreements to strategic long-term partnerships. Companies were asked about potential areas of collaboration such as sharing transport vehicles, warehouse infrastructure, joint procurement and coordinating delivery schedules. This helps us to evaluate opportunities and willingness of companies to integrate and manage pooled resources. Questions on potential benefits in terms of cost reduction, improved vehicle utilization and enhanced service offerings further clarified companies’ motivation. Further analysis delved into conditions necessary for successful collaboration such as transparency in operations, secure data management and unified rules for resource sharing and conflict resolution. This highlighted opportunities that enable lasting partnerships. Finally, questions on innovative practices such as shared autonomous systems or digital platforms for joint decision making captured both opportunity and motivation. This structure ensures our methodology reflects the basic nature of COM-B in the HLC context. Questions were structured using a 5-point Likert scale, ranging from 1 (not important/inappropriate) to 5 (very important/very appropriate), to ensure detailed insights into perceptions and priorities. By including these comprehensive content areas, the survey provided a robust framework for evaluating the challenges and opportunities within the Slovenian logistics sector and identifying means for fostering horizontal collaboration. The target population included logistics companies classified under standard activity codes such as universal postal service activities, road freight transport, warehousing, cargo handling, and other transportation support activities. A total of 7217 companies were registered in Slovenia in this segment, as identified through the GVIN database [ 35 ]. However, public databases typically do not provide accessible contact information for these companies. To address this, the questionnaire was disseminated through the mailing lists of the Chamber of Commerce and Industry of Slovenia and the Chamber of Craft and Small Business of Slovenia. We chose this approach because the publicly available company database only lists generic information email addresses, to which firms typically do not respond. Consequently, not all companies were included in the survey, which represents a limitation of the study. Nevertheless, we believe that the sample includes representative stakeholders. Structured interviews with selected industry stakeholders were conducted to refine the questionnaire, ensuring clarity and consistency in interpretation. Feedback led to iterative improvements before the survey’s distribution. Data collection took place between April and September 2024. Companies were first invited to participate via email, followed by reminder phone calls to improve response rates. Participants were informed about the study’s purpose, and their consent was obtained before participation. This approach yielded 71 valid responses, representing a diverse crosssection of the Slovenian logistics industry. Respondents included 13.7% large enterprises, 19.2% medium-sized enterprises, 43.8% small enterprises, and 23.3% micro-enterprises. Most surveyed companies primarily offered transport services (97.2%), with additional Sustainability 2025,17, 7001 6 of 30 services such as warehousing (45.8%) and value-added services like packaging and labelling (22.2%). Among transport providers, 74.6% offered international transport, 64.8% offered local/urban transport, and 62.0% provided national/regional transport. The sample presented in Figure 1is statistically significant as it represents a broad spectrum of company sizes and services, capturing the diversity and complexity of the Slovenian logistics industry. It includes a balanced mix of micro, small, medium, and large enterprises. Furthermore, the 71 valid responses account for approximately 1% of all logistics companies registered in Slovenia, ensuring a meaningful representation of the industry. By covering diverse service offerings, including transport, warehousing, and value-added services, the sample reflects both common practices and niche operations. This structured approach not only minimizes sampling bias but also ensures that the insights derived are robust and applicable to the sector’s broader trends and challenges. Figure 1. Distribution of registered logistics companies and surveyed companies based on the standard classification of activities. Survey responses were analysed to identify patterns in readiness, motivations, and barriers to collaboration. Comparative analysis was conducted between companies of different sizes, service types, and operational focuses. Insights from structured interviews were integrated to contextualize the survey findings. For each of the possible answers on current issues, forms, areas of collaboration, benefits, and necessary conditions for successful collaboration, we analysed the averages and standard deviation of responses, which are presented in graphs of the following chapter. Subsequently, we also calculated the percentage deviation of the average of the responses of each group of companies from the overall average. These data are presented in the tables in Appendix A. Blue-coloured cells represent a negative deviation (e.g., a specific form of cooperation is less suitable for this group of enterprises), red-coloured cells represent a positive deviation (e.g., a specific form of cooperation is more suitable for this group of enterprises). White-coloured cells represent a minimum deviation from the average. Additionally, a statistical analysis was performed using SPSS programme (IBM Corp. Released 2023. IBM SPSS Statistics for Windows, Version 29.0.2.0 Armonk, NY, USA: IBM Corp). Several statistical tests were made to identify statistically relevant correlations between different company types and questions related to current issues, forms, areas of collaboration, benefits, and necessary conditions for successful collaboration. Further, Sustainability 2025,17, 7001 7 of 30 statistical tests were conducted to identify statistically relevant correlations between the possible answers to a specific question related to current issues and collaboration. Several statistical tests were conducted to examine correlations between different types of companies and relationships within responses to questions on current issues and collaboration. These included the Spearman correlation, Mann–Whitney U test, Kruskal–Wallis H test, and Friedman test. Statistically significant correlations were identified at p< 0.05. Additionally, graphical representations such as boxplots, bar charts, scatter plots, relationship maps, and crosstabs were created to illustrate key findings. While the statistical tests were performed using SPSS, they are not included in this article but are available upon request from the author. Comments below the graphs in the following section highlight only those relationships that were found to be statistically significant. While the study focuses on Slovenia, which may limit the generalizability of findings, it provides valuable insights into the factors influencing horizontal logistics collaboration in highly fragmented and competitive markets. The methodology offers a robust framework that can be adapted to similar environments. 3. Results The survey responses were analysed to provide a detailed understanding of the challenges, experiences, and motivational factors influencing the readiness of Slovenian logistics companies to engage in horizontal collaboration. The analysis explicitly compares the responses of companies depending on their size, provided type of services, and prior collaboration experiences, offering a detailed perspective on how these groups perceive challenges and opportunities differently. The findings are presented in the following sections, which align with the study’s objectives, while their interpretation and broader implications are discussed in the subsequent section. For a more detailed view, Appendix Aincludes detailed tables showing percentage deviations in responses across different company types compared to the overall average. 3.1. Collaboration Perspectives Across Different Company Types All surveyed companies regardless of their company type answered the questions regarding the current issues when performing logistics processes, most appropriate forms and areas of collaboration, and what benefits and conditions of collaboration are most important for them. Averages of answers are presented in the following graphs. For each of the questions, a table is provided in Appendix Ashowcasing which of the provided answers are, in relative terms, more (red colour) or less important (blue colour) based on the company type. The number in the table indicates the percentage deviation of responses from the weighted average. When examining the issues faced by logistics companies, we presented the respondents with 16 of the most common challenges identified from the literature review (Figure 2). The identified challenges were ranked based on how significantly they affect logistics processes. A rating of 1 indicates that the challenge does not significantly impact companies’ logistics processes, while a rating of 5 indicates that the issue has a very significant impact. The analysis identified five key challenges for logistics service providers, each rated with average importance above 4.0: labour shortages (4.18), traffic congestion (4.17), unfair competition (4.08), low utilization (4.07), and high energy costs (4.06). The least important issues are a lack of investment funds (3.14) and urban delivery restrictions (3.33). The standard deviation values (ranging from 1.0 to 1.2) and a coefficient of variation (0.2–0.4) indicate a moderate dispersion of responses, suggesting a relatively consistent perception of logistics challenges among respondents. A more detailed interpretation of these results is provided in the Discussion section. Sustainability 2025,17, 7001 8 of 30 Figure 2. Average values for issues of logistics companies affecting their logistics processes. Companies providing only transport services report significantly greater challenges than those offering diversified logistics services. Additionally, firms with prior collaboration experience report more challenges. In terms of company size, the labour shortage is a more pressing issue for large companies, while a lack of investment funds, payment indiscipline, a lack of knowledge on optimization, and time loss due to traffic congestion are more pressing for SMEs. Companies unwilling to collaborate face greater challenges, including labour shortages, lack of investment funds, loss of time due to traffic congestion and high energy costs. They also report payment indiscipline, demanding customer requirements, lack of trust, and unfair competition, reinforcing barriers to cooperation. Companies serving in the B2C sector experience the listed issues as slightly more pressing than those in the B2B sector. Similarly, firms operating zero-emission vehicles report these challenges as somewhat more demanding. Logistics operators owning larger storage capacities experience more pressing issues of low utilization of space and labour shortage than those with less storage space owned. The statistical analysis also identified that traffic congestion and loss of time are very important issues for companies operating in the B2C sector rather than in other sectors; additionally, payment indiscipline is a much more pressing issue for companies providing only transport services (boxplot graph in Supplementary Material, Figure S1); further, labour shortage is a more significant issue for companies owning zero-emission vehicles rather than those that do not. A key insight is the strong correlation between lack of trust Sustainability 2025,17, 7001 9 of 30 and lack of collaboration (details in Supplementary Material, Figure S2). The higher the lack of trust, the more significant the collaboration issue. No significant differences were observed between companies based on the spatial scope of their transport services, whether international (long distance), national or regional (medium distance), or local/urban (short distance). This can be attributed to the fact that many challenges such as labour shortages, high energy costs, or payment indiscipline affect logistics providers across all levels of transport activity and are not strictly tied to distance or delivery range. There are also no mayor differences in terms of perceived issues and the company’s vehicle fleet size. 3.2. The Most Appropriate Forms of Collaboration Further, we asked logistics companies about the most appropriate forms of collaboration. The responses to this question are presented in Figure 3, where 1 indicates “inappropriate” and 5 indicates “very appropriate” form of collaboration. Figure 3. Average values for forms of collaboration appropriate for logistics companies. An analysis shows that the most suitable forms of collaboration are joint planning of operational logistics processes (3.96) and collaboration and networking with several partners (3.75); these are further interpreted in the following section. The standard deviation values (1.0–1.2) and the coefficient of variation (0.3) suggest a moderate spread in responses, indicating relative agreement among participants. Companies with larger storage capacities (over 5000 m 2 ), prior collaboration experience, and a higher willingness to collaborate are generally more open to all forms of cooperation. Micro-sized companies prefer collaboration with a single partner, whereas medium and large companies favour collaboration and networking with several partners (Spearman test and bar chart available in Supplementary Material, Table S1 and Figure S3). B2B operators prefer collaboration with a single partner, whereas B2C companies find this approach significantly less suitable. For companies with a large vehicle fleet, collaboration and networking with several partners is significantly more suitable than for those with a smaller fleet. Similarly, logistics providers that own zero-emission vehicles find multipartner collaboration and networking particularly beneficial, whereas companies without such vehicles view this form of cooperation as considerably less desirable. Among logistics companies providing only transport, the most suitable forms of collaboration are limited to working with a single partner or engaging in the joint planning of operational logistics processes. In contrast, companies offering a broader range of logistics services tend to prefer strategic, long-term partnerships and multi-partner collaboration models. Sustainability 2025,17, 7001 16 of 30 experience. In doing so, they serve as transitional mechanisms that help companies build mutual confidence and enter longer-term partnerships. Third, transparent rules for costand carbon-sharing are essential [ 29 ]. To ensure fairness and long-term commitment, collaboration frameworks must include clear and preagreed mechanisms for distributing both the benefits and burdens of cooperation, including financial investments, operational effort, and emission reductions. For example, if shared use of electric vehicles or consolidation centres is part of the agreement, the costs and carbon savings should be proportionally distributed among the partners. This increases trust, reduces conflicts, and strengthens commitment, particularly in environmentally sensitive urban logistics contexts such as zero-emission zones. Equally important is the alignment of key performance indicators (KPIs) with both collaborative and sustainability goals. Partners should define and monitor KPIs that reflect not only operational efficiency (e.g., on-time delivery or resource utilization), but also environmental performance (e.g., CO 2 reductions, energy efficiency, or share of zero-emission deliveries). This ensures that sustainability is not treated as a secondary objective, but as a shared, measurable outcome of collaboration. Fourth, behavioural incentives should complement technical and infrastructural measures. Current policy instruments often focus narrowly on infrastructure, digitalization, or environmental targets. However, behavioural change requires behavioural tools. We recommend introducing collaboration-readiness criteria in public procurement and funding programmes, especially in logistics services for public institutions. Pre-competitive pilot projects should be supported by public funding, accompanied by behavioural diagnostics that help identify potential blockers within organizations. Furthermore, financial incentives (e.g., tax reductions, grants) for companies engaging in collaborative zero-emission delivery models would directly support both environmental and structural sustainability goals [ 43 ]. Finally, the transition from temporary pilot projects to stable, long-term collaboration networks require policy support that explicitly links logistics innovation with sustainability goals. Sustainable development must move from being a peripheral concern to a core strategic driver of logistics collaboration. This includes not only promoting zeroemission vehicles and low-carbon operations but also rewarding collaborative models that demonstrably reduce environmental externalities [ 44 ], improve urban quality of life, and support SMEs’ long-term viability. Policymakers should recognize that fostering logistics collaboration is not just an economic or operational issue, but a strategic tool for achieving climate goals, economic resilience, and sustainable supply chain and logistics management. The potential of logistics collaboration is real, but its activation depends not on new technologies or regulations alone, but on shifting the behavioural foundations on which logistics decision-making rests. Trust, transparency, and fairness are not optional soft factors [ 19 , 20 , 29 ]; they are structural prerequisites for unlocking a more efficient, sustainable, and resilient logistics system, one that can work for both large and small actors, and one that welcomes both experienced and new collaborators. 5. Conclusions Rapid changes in the logistics sector are forcing companies to adapt to workforce shortages, rising costs, and growing competition. Horizontal logistics collaboration (HLC) offers a promising solution, enabling firms to share resources, optimize operations, and improve efficiency. This study explores HLC in Slovenia, where collaboration remains limited, by combining a literature review with a survey of 71 logistics operators. It offers a unique contribution by addressing several key gaps in the literature. First, it focuses explicitly on micro and small enterprises, which are often overlooked despite representing the majority of logistics providers and facing the most significant operational constraints. Sustainability 2025,17, 7001 17 of 30 Second, it captures the perspectives of both collaborative and non-collaborative firms, enabling a comparative analysis of their motivations, barriers, and readiness levels. Third, by applying the COM-B model to structure and interpret survey results, the study links behavioural dimensions to operational and strategic decision-making, offering a more nuanced understanding of collaboration dynamics. Fourth, the study undertakes an integrated and detailed analysis by examining collaboration patterns in relation to a wide typology of logistics firm characteristics, including company size, types of services offered, customer segments served, transport activity intensity, fleet composition, and storage capacities. This approach provides a robust evidence base for understanding how structural and strategic features influence collaboration readiness and behaviour. Finally, it provides context-specific insights from a highly competitive logistics environment where collaboration is both difficult and urgently needed. Survey results show that key challenges include labour shortages, congestion, unfair competition, low asset utilization, and energy costs. Trust emerged as a critical enabler. Companies with prior collaboration experience reported fewer operational issues and a higher willingness to engage again. This suggests that positive collaboration experiences can reduce perceived risks and unlock long-term benefits. The most preferred collaboration models involve joint operational planning, networking with multiple partners, shared infrastructure, and knowledge exchange. Successful collaboration depends on clear rules, secure data sharing, partner commitment, process transparency, and preserving autonomy. Importantly, company size and past experience shape attitudes. Micro firms are more open to collaboration, while larger firms, typically more self-sufficient, are selective but more likely to commit long term. While our findings indicate that economic and operational incentives currently outweigh sustainability concerns, this observation should not be interpreted as dismissing the strategic relevance of sustainability. On the contrary, the behavioural barriers identified, such as lack of trust, reputational concerns, and operational stress, highlight the need for integrative approaches that align efficiency goals with environmental and social responsibility. As such, sustainability should be reframed not merely as an external compliance issue but as a lever for trust building, long-term competitiveness, and systemic resilience in fragmented logistics markets. Future collaboration models that embed carbon sharing rules, green procurement, and performance indicators tied to ESG goals may help reposition sustainability as a primary behavioural driver rather than a peripheral outcome. To increase adoption, policies should align economic incentives with environmental goals and build trust through neutral platforms and transparent rules. All of the aforementioned results are based on surveys performed in Slovenia, but may apply to other countries with fragmented logistics markets and low collaboration levels. Despite the well-documented benefits of horizontal collaboration, its widespread adoption remains a challenge. Future research should focus on identifying effective behaviour change strategies that encourage logistics companies to engage in cooperative efforts, taking into account key motivational factors and the conditions necessary for successful collaboration. Trust-building measures, incentive structures tailored to company size, prior experience, and willingness to collaborate, as well as clearly defined collaboration frameworks, will be essential in overcoming existing barriers. Expanding the scope of research to include logistics firms from other countries would provide a broader perspective on the most desirable areas of collaboration, key motivational drivers, and the conditions that facilitate successful partnerships, ultimately contributing to the development of more targeted and effective collaboration models. Sustainability 2025,17, 7001 18 of 30 Supplementary Materials: The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/su17157001/s1. Online survey: Collaboration between logistics operators. Figure S1: Boxplot comparison of the perceived severity of payment indiscipline between companies offering only transport services and those providing a full range of logistics services; Figure S2. Bar chart showing the correlation between higher perceived lack of trust and increased perceived lack of collaboration among logistics service providers; Table S1. Spearman test showing statistically relevant correlation between company size and collaboration with several partners; Figure S3. Bar chart showing the correlation between company size and increased suitability to collaboration with several partners; Table S2. Spearman test showing statistically relevant correlations between willingness to collaborate and possible areas of collaboration; Table S3. Mann–Whitney U test showing statistically relevant correlation between prior collaboration experience and improved vehicle optimization; Figure S4. Bar chart showing how collaborative and non-collaborative companies rate the benefit of improved vehicle optimization; Table S4. Spearman test showing statistically relevant correlations between willingness to collaborate and conditions for successful collaboration. Author Contributions: Conceptualization, I.P. and T.L.; methodology, I.P. and T.L.; validation, I.P.; formal analysis, I.P.; investigation, I.P.; data curation, I.P.; writing—original draft preparation, I.P. and T.L.; writing—review and editing, I.P. and T.L.; visualization, I.P.; supervision, T.L.; funding acquisition, T.L. All authors have read and agreed to the published version of the manuscript. Funding: This research was funded by European Climate, Infrastructure and Environment Executive Agency, grant number 101104278 (project TRACE). Institutional Review Board Statement: We would like to clarify that this study does not involve any research with human subjects, human tissue or personal data. This study was based on a structured online survey for legal entities (logistics companies) and no individual-level or sensitive personal data was collected. In addition, an informed consent form was attached at the beginning of the questionnaire, clearly stating the purpose of the study, the voluntary nature of participation, and the confidentiality of the data. Only participants who confirmed their consent were allowed to proceed with the survey. It was confirmed by the institution that such research does not require approval from an ethics committee. This is consistent with similar studies previously published by our institute. Informed Consent Statement: Informed consent was obtained from all subjects involved in the study. Data Availability Statement: Data are available and stored locally by the author. Conflicts of Interest: The authors declare no conflicts of interest. Appendix A The following tables present percentage deviation responses of each group of companies from the overall average. Blue-coloured cells represent a negative deviation (less than average); red-coloured cells represent a positive deviation (more than average). Whitecoloured cells represent a minimum deviation from the overall average. The tables in this appendix are ordered by the survey questions related to challenges and cooperation. There is one table for each question, which is divided into three parts due to its size (e.g., Table A1a–c). Sustainability 2025,17, 7001 19 of 30 Appendix A.1 Issues Affecting Logistics Processes Table A1. How importantly do these issues affect your work and logistics processes? A1(a) Q3 How Big Is Your Company According to the EU Classification? Q4 Which Segment Do You Operate in? Q5 What Logistics Services Do You Offer? Q10 How Importantly Do These Issues Affect Your Work and Logistics Processes? Micro Small Medium Large Companies (B2B) End Consumers (B2C) ALL Transport Transport and Other Low utilization (freight vehicles, storage facilities) −4% −7% 7% 16% 4% −21% −8% 1% 0% Labour shortages (large fluctuation of staff) −2% −3% −1% 9% 1% −38% 4% −4% 2% Lack of investment funds 7% −2% −9% 4% 5% −5% −9% 11% −6% Demanding customer requirements (fragmentation) −5% −3% 11% −4% 0% −16% 1% 0% 2% High energy costs −3% 5% −10% −1% 4% 8% −13% 5% −2% Payment indiscipline 3% 1% −4% −4% 1% 13% −7% 11% −6% Lack of trust between logistic operators −2% 3% 0% −10% 1% 4% −5% 7% −2% Lack of collaboration between logistic operators 1% 2% −2% −11% 2% −3% −5% 4% 0% Lack of knowledge on optimization and modern IT solutions 3% −5% 7% −1% 0% −25% 6% 3% −2% Lack of data for proper management of logistics processes 2% −5% 2% 6% −1% 3% −1% 4% 1% Unfair competition −3% 0% 3% −2% 3% −2% −9% 6% −1% Traffic congestion (loss of time) 8% −1% −4% −11% 3% 15% −11% 4% 0% Environmental constraints (Euro norms) −3% 2% 4% −15% 3% 14% −12% 8% −4% Legislative constraints (ESG rules for measuring and reporting environmental and social impacts) −3% −1% 12% −8% −1% 5% 1% 2% 0% Urban delivery restrictions (UVAR) 3% −4% −3% 7% 0% 10% −1% 12% −2% Lack of adequate logistics infrastructure in cities (delivery points, handling equipment) 0% −3% −6% 4% −1% 12% −4% 10% −1% Sustainability 2025,17, 7001 20 of 30 Table A1. Cont. A1(b) Q6 Vehicle Fleet Size? Q7 Zero-Emission Vehicles? Q8 Existing Storage Capacity [m2]? Q11 Have You Ever Collaborated with other Logistics Service Providers? Q10 How Importantly Do These Issues Affect Your Work and Logistics Processes? 0–50 >50 Yes No 0–1000 1001–5000 >5000 Yes No Low utilization (freight vehicles, storage facilities) −1% 8% 6% 1% 0% 4% 7% −1% −5% Labour shortages (large fluctuation of staff) −2% 5% 12% −2% 5% 4% 8% 0% −4% Lack of investment funds 3% −3% 8% 2% 0% 1% −15% −1% 7% Demanding customer requirements (fragmentation) 0% 6% 7% 2% −1% 7% −7% 0% −2% High energy costs 6% −9% −3% 4% 16% −12% −1% 1% −11% Payment indiscipline 3% −5% −1% 3% 1% −3% −10% 0% 0% Lack of trust between logistic operators 1% 5% 5% 2% 1% 5% −8% 1% −7% Lack of collaboration between logistic operators 1% 3% 4% 2% 4% 6% −10% 1% −9% Lack of knowledge on optimization and modern IT solutions −2% 6% 2% 1% 0% −2% −4% 1% −10% Lack of data for proper management of logistics processes 1% 3% 1% 3% −4% 3% 5% 0% −7% Unfair competition 1% 6% 11% 0% −4% 8% −6% 0% −8% Traffic congestion (loss of time) 3% −6% 1% 2% 12% −8% −20% 1% −7% Environmental constraints (Euro norms) 4% −6% 5% 1% 14% −15% 0% −1% 0% Legislative constraints (ESG rules for measuring and reporting environmental and social impacts) 1% −2% 1% −1% 14% −10% 2% 1% −5% Urban delivery restrictions (UVAR) 4% −2% 1% 0% 12% −7% −15% −1% 10% Lack of adequate logistics infrastructure in cities (delivery points, handling equipment) 2% 5% 5% 2% 8% 4% −16% −1% −6% Sustainability 2025,17, 7001 21 of 30 Table A1. Cont. A1(c) Q12 How Would You Rate Your Willingness to Collaborate with Other Logistics Service Providers? Q10 How Importantly Do These Issues Affect Your Work and Logistics Processes? I’m Not Willing to Collaborate with Other Logistics Service Providers I’m Only Willing to Collaborate if Absolutely Necessary I’m Willing if the Collaboration Is Easy to Organize I’m Very Willing to Collaborate and Share My Resources I’m Fully Willing to Collaborate and to Establish a Lasting Collaboration Low utilization (freight vehicles, storage facilities) 11% −10% −6% 0% 11% Labour shortages (large fluctuation of staff) 20% −10% −4% 1% 5% Lack of investment funds 27% −1% −1% 5% −7% Demanding customer requirements (fragmentation) 25% −4% 1% 1% −7% High energy costs 11% −12% 2% 0% −3% Payment indiscipline 29% −3% −2% 1% 0% Lack of trust between logistic operators 10% −18% 1% 4% 3% Lack of collaboration between logistic operators −19% −7% −1% 8% 1% Lack of knowledge on optimization and modern IT solutions −28% −14% −1% 13% 2% Lack of data for proper management of logistics processes −4% −4% −2% 8% −3% Unfair competition 22% −8% −2% 2% 1% Traffic congestion (loss of time) 8% −7% 0% −2% 4% Environmental constraints (Euro norms) 0% 11% 1% −6% −7% Legislative constraints (ESG rules for measuring and reporting environmental and social impacts) −13% 7% 1% −13% 7% Urban delivery restrictions (UVAR) 13% 1% −17% 2% Lack of adequate logistics infrastructure in cities (delivery points, handling equipment) −2% −1% −9% 4% Sustainability 2025,17, 7001 22 of 30 Appendix A.2 Forms of Collaboration Table A2. Which forms of collaboration are appropriate for you? A2(a) Q3 How Big Is Your Company According to the EU Classification? Q4 Which Segment Do You Operate in? Q5 What Logistics Services Do You Offer? Q13 Which Forms of Collaboration Are Appropriate for You? Micro Small Medium Large Companies (B2B) End Consumers (B2C) ALL Transport Transport and Other Collaboration with a single partner only 14% −8% −2% −4% 6% −24% −8% 4% 0% Collaboration and networking with several partners −7% −2% 7% 14% −2% −4% 3% −3% 3% Joint planning of operational logistics processes 5% −6% 8% −9% −4% −1% 8% 2% 0% Strategic and long-term collaboration 6% −8% 1% 8% −2% −4% 2% −3% 2% A2(b) Q6 Vehicle Fleet Size? Q7 Zero-Emission Vehicles? Q8 Existing Storage Capacity [m2]? Q11 Have You Ever Collaborated with Other Logistics Service Providers? Q13 Which Forms of Collaboration Are Appropriate for You? 0–50 >50 Yes No 0–1000 1001–5000 >5000 Yes No Collaboration with a single partner only 1% 0% 6% −2% −10% 9% 7% 1% −9% Collaboration and networking with several partners −3% 10% 9% −2% −2% 2% 20% 1% −13% Joint planning of operational logistics processes 0% 1% −6% 2% 0% −6% 21% 3% −24% Strategic and long-term collaboration 0% −2% −3% 0% −1% −1% 14% 1% −12% A2(c) Q12 How Would You Rate Your Willingness to Collaborate with Other Logistics Service Providers? Q13 Which Forms of Collaboration Are Appropriate for You? I’m Not Willing to Collaborate with Other Logistics Service Providers I’m Only Willing to Collaborate if Absolutely Necessary I’m Willing if the Collaboration is Easy to Organize I’m Very Willing to Collaborate and Share My Resources I’m Fully Willing to Collaborate and to Establish a Lasting Collaboration Collaboration with a single partner only −12% −9% 0% 12% −5% Collaboration and networking with several partners −20% −14% −3% 4% 12% Joint planning of operational logistics processes −28% −10% −9% 14% 14% Strategic and long-term collaboration −12% −16% −3% −1% 15% Sustainability 2025,17, 7001 23 of 30 Appendix A.3 Areas of Collaboration Table A3. In which areas do you see possibilities/opportunities for collaboration? A3(a) Q3 How Big Is Your Company According to the EU Classification? Q4 Which Segment Do You Operate in? Q5 What Logistics Services Do You Offer? Q14 In Which Areas Do You See Possibilities/Opportunities for Collaboration? Micro Small Medium Large Companies (B2B) End Consumers (B2C) ALL Transport Transport and Other Sharing warehouse infrastructure 0% −3% 8% −21% −3% −5% 3% 3% −1% Sharing transport vehicles −3% −6% 11% 4% 5% −44% −3% −5% 3% Sharing handling equipment 9% −10% 14% −17% −2% −40% 14% −2% 2% Sharing workforce 7% −6% 8% −11% −1% −43% 10% −5% 4% Sharing or merging shipments in delivery 1% 8% −2% −41% −2% 19% −1% 6% −3% Sharing of data 20% −1% −8% −37% 1% −53% 8% 1% −1% Sharing experiences and knowledge 7% −8% 4% −5% −3% −8% 6% −7% 6% Joint procurement of fuel, spare parts, materials, packaging, IT services 5% −7% 16% −24% 3% −51% 1% 4% −1% Sharing of autonomous systems (transport and/or storage) 12% −8% 11% −33% 0% −39% 6% 6% −5% A3(b) Q6 Vehicle Fleet Size? Q7 Share of Zero-emission Vehicles? Q8 Existing Storage Capacity [m2]? Q11 Have You Ever Collaborated with Other Logistics Service Providers? Q14 In Which Areas Do You See Possibilities/Opportunities for Collaboration? 0–50 >50 Yes No 0–1000 1001–5000 >5000 Yes No Sharing warehouse infrastructure 0% 7% 4% 2% 4% −5% 21% 2% −25% Sharing transport vehicles −3% 13% 15% −2% 1% 7% 9% 1% −14% Sharing handling equipment −3% 9% −10% 3% 8% −8% 6% 2% −21% Sharing workforce −5% 14% 8% −1% −15% 14% 1% 3% −19% Sharing or merging shipments in delivery 7% −17% −16% 7% 14% −18% 14% 3% −26% Sharing of data 6% −17% −4% 2% −4% −8% 7% 3% −24% Sharing experiences and knowledge −2% 7% 6% 0% −3% 17% 0% 2% −25% Joint procurement of fuel, spare parts, materials, packaging, IT services 2% 3% −5% 5% −8% 3% 24% 2% −19% Sharing of autonomous systems (transport and/or storage) 1% −1% −10% 5% −9% −8% 18% 2% −20% Sustainability 2025,17, 7001 24 of 30 Table A3. Cont. A3(c) Q12 How Would You Rate Your Willingness to Collaborate with Other Logistics Service Providers? Q14 In Which Areas Do You See Possibilities/Opportunities for Collaboration? I’m Not Willing to Collaborate with Other Logistics Service Providers I’m Only Willing to Collaborate if Absolutely Necessary I’m Willing if the Collaboration Is Easy to Organize I’m Very Willing to Collaborate and Share My Resources I’m Fully Willing to Collaborate and to Establish a Lasting Collaboration Sharing warehouse infrastructure 11% −33% 2% 14% −5% Sharing transport vehicles 9% −45% −1% 18% 7% Sharing handling equipment 0% −37% −3% 13% 17% Sharing workforce 33% −48% −2% 11% 17% Sharing or merging shipments in delivery 34% −41% 6% 19% −13% Sharing of data −5% −48% 2% 25% 0% Sharing experiences and knowledge −28% −30% −3% 21% 6% Joint procurement of fuel, spare parts, materials, packaging, IT services 14% −19% −14% 30% 9% Sharing of autonomous systems (transport and/or storage) 18% −29% −3% 32% −6% Sustainability 2025,17, 7001 25 of 30 Appendix A.4 Benefits of Collaboration Table A4. How important would certain benefits of collaboration influence you to be more willing to collaborate? A4(a) Q3 How Big Is Your Company According to the EU Classification? Q4 Which Segment Do You Operate in? Q5 What Logistics Services Do You Offer? Q15 How Important Would Certain Benefits of Collaboration Influence You to Be More Willing to Collaborate? Micro Small Medium Large Companies (B2B) End Consumers (B2C) ALL Transport Transport and Other Improved optimization and efficiency of logistics processes −5% −2% 3% 7% 1% −7% −3% −3% 2% Reduced costs, increased demand −1% −2% 4% −1% 0% −5% −1% 1% 0% Less negative impact on the environment −11% 2% 5% 1% 1% 4% −6% 4% −2% Better vehicle utilization, fewer empty runs −4% 2% 0% −7% 1% 5% −7% −1% 0% Increased competitiveness and bargaining power −5% −4% 10% 0% 0% −7% 0% −7% 6% Faster, more frequent and punctual deliveries −6% 2% 1% −3% −1% −5% 0% 2% −3% Increased customer flexibility, diversification of logistics service offer −9% −2% 5% 14% −1% −11% 0% −2% 2% Increased flexibility to comply with ESG standards (measurement and reporting of environmental and social impacts) −9% 1% 7% −4% 1% −14% −4% 2% 0% Increased flexibility to new rules for deliveries to city centres 0% −2% 0% 1% −4% 16% 3% 5% −1% A4(b) Q6 Vehicle Fleet Size? Q7 Share of Zero-Emission Vehicles? Q8 Existing Storage Capacity [m2]? Q11 Have You Ever Collaborated with Other Logistics Service Providers? Q15 How Important Would Benefits of Collaboration Influence You to Be More Willing to Collaborate with Other Logistics Service Providers? 0–50 >50 Yes No 0–1000 1001–5000 >5000 Yes No Improved optimization and efficiency of logistics processes 1% −1% −3% 2% 6% −1% 3% 1% −16% Reduced costs, increased demand 1% −2% 1% 0% 4% −9% 15% 1% −12% Less negative impact on the environment 2% −1% −3% 4% 6% −8% −3% 0% −7% Better vehicle utilization, fewer empty runs 2% −1% 3% 1% 6% 1% −3% 0% −13%