Developing a Sustainable Urban Mobility Maturity Model

Abstract

This study introduces the Sustainable Urban Mobility Maturity Model (SUM-MM) to assess and enhance the maturity of sustainable urban mobility in cities. The SUM-MM comprises 3 main dimensions (enablers, sustainability, and transport modes) and 11 sub-dimensions (strategic and spatial planning, organization and human resources, information and communication technologies, environment, economy, social, walking, micromobility, public transport, paratransit systems, and multimodal integration), evaluated at 5 levels (beginner, initial, integrated, managed, and mature). Developed through a literature review and validated using a questionnaire-based expert opinion method, the model was tested in Konya, Türkiye. The results show that Konya’s overall maturity falls between integrated and managed, with significant variability across sub-dimensions. The enablers dimension demonstrated the highest maturity, driven by strong organizational and technological capabilities, whereas the transport modes dimension had the lowest—particularly in paratransit systems. The SUM-MM serves as both a benchmarking tool and a policy guidance framework, facilitating targeted strategies for sustainable urban mobility improvements. Unlike existing smart city or transport maturity models, the SUM-MM specifically focuses on sustainable urban mobility, offering a structured, operational, and decision-oriented framework for policy-makers and city administrations. The results can be used by local and national authorities to support comparative benchmarking, strategic planning, and the prioritization of sustainable urban mobility investments.

1. Introduction

On a global scale, projections suggest that urban areas will accommodate an estimated 68% of the world’s population by the year 2050 [1]. This rapid urbanization highlights the crucial importance of sustainable urban mobility solutions in addressing associated challenges such as traffic congestion, environmental degradation, and public health concerns. As cities continue to grow, prioritizing sustainable transportation becomes essential to maintaining the livability and resilience of urban environments.

The European Union (EU) Green Paper highlighted the challenges of unsustainable mobility systems and advocated the promotion of efficient urban and regional transportation while reducing car traffic and even encouraging lower transport demand [2]. Cities also develop Sustainable Urban Mobility Plans (SUMPs), which represent a comprehensive and strategic method to effectively address the complex challenges of urban transportation. The central objective is to enhance accessibility and enhance quality of life by implementing a transition toward sustainable mobility [3]. The adoption of SUMPs or engagement in SUMP activities in cities is linked to reduced private car usage, likely due to the connection between SUMPs and effective sustainable transport measures [4]. For example, previous research highlights that well-developed bicycle systems and high-quality cycling infrastructure can significantly increase bicycle usage, thereby supporting sustainable urban mobility objectives [5].

Sustainable mobility measure investments are constrained due to limited financial resources in most cities. The need to assess, evaluate, and manage a city’s development strategies for sustainability becomes evident due to financial limitations and the requirement for effective approaches in addressing growing pressures on urban ecosystems [6]. Assessment approaches can broadly be divided into two complementary approaches: indicator-based evaluation methods and maturity models. Indicator-based evaluation methods objectively measure performance using quantitative metrics, and maturity models provide a more qualitative and structured framework to evaluate capacities. Assessing and determining maturity in sustainable mobility is important for the prioritization and implementation of strategies. A literature review was conducted to determine the maturity of urban mobility in cities. However, although some publications have dealt with smart city maturity assessment [6,7,8,9,10,11], reports on the maturity assessment of sustainable mobility could not be found during this literature search.

The conceptual foundation of the SUM-MM is grounded in maturity model theory, which assumes that organizational and system development progresses through sequential and increasingly structured stages [12]. Consistently with maturity development logic in the literature, the SUM-MM operationalizes sustainable urban mobility as a multi-layered construct shaped by governance capacity, sustainability outcomes, and transport mode integration [13]. Thus, maturity reflects not only infrastructure availability but also institutional capability, policy coherence, user inclusiveness, and systemic integration, aligning with contemporary sustainable mobility governance perspectives.

Maturity models enable cities to compare themselves with other cities, as well as with themselves in different years. A maturity model usually analyzes the level of achievement of a set target through institutional structures and processes [14]. Assessing sustainable urban mobility is a complex task, involving the assessment of various dimensions. A comprehensive evaluation of a city’s current state is crucial, considering the involved factors influencing urban mobility. A holistic approach is expected to provide decision-makers with a better understanding to enhance sustainable and efficient urban mobility systems. This study fills the gap in the literature by creating a Sustainable Urban Mobility Maturity Model for cities and develops, validates, and tests the SUM-MM to assess city maturity and guide improvements. This study is structured as follows. Section 2 presents a review of the maturity model literature. Section 3 introduces the draft model by identifying its maturity levels, dimensions, and sub-dimensions and explains how the model was populated and validated with expert opinions. Section 4 provides the results of applying the model to the case of Konya City. Finally, Section 5 concludes the study and discusses the findings, highlighting directions for future research.

2. Literature Review

Studies have focused on indicator-based methods to assess transport sustainability, systematically reviewing and classifying performance metrics across themes such as safety, mobility, emissions, and accessibility [15]. In contrast to indicator-based approaches, this section continues with a review of maturity model studies. Maturity models facilitate internal and/or external benchmarking, highlight areas for improvement, and guide development. They aim to describe stages of maturation and the relationships between them. The main premise is that higher maturity levels indicate more advanced capability and positive change, while the model captures this process conceptually and supports assessment.

While multi-criteria decision-making (MCDM) approaches such as the AHP are frequently used to prioritize and rank alternatives, recent studies have also proposed hybrid approaches—for example, using MCDM techniques to support the construction of indicators—although the overarching purpose remains the evaluation of developmental stages rather than ranking [7]. Maturity models conceptualize development as a staged progression in which each level reflects a more advanced state of capability, integration, and governance. Rather than providing only a numerical output, they offer a diagnostic perspective that helps to identify the current maturity position and guide improvement pathways [16]. Lasrado et al. [16] conducted a literature review focused on maturity models and identified three meta-models for developing maturity models (

Table 1. Comparison of meta-models for developing maturity models.

Six Phases of Developing MM [17]	Developing MM for IT Management [12]	Five Steps for Developing Stage of Growth MM [18]
Scope	Problem Definition	Suggested Stage Model
Design	Comparison of Existing Models	Conceptual Model
Populate	Determination of Development Strategy	Theoretical Model
Test	Iterative Development Process	Empirical Model
Deploy	Conception of Transfer and Evaluation	Revised Stage Model
Maintain	Implementation of Transfer Media
	Evaluation
	Rejection of Maturity Model

).

De Bruin et al. [17] created a developmental model comprising six phases, incorporating the idea of maturity model layers and providing a framework for specifying attributes. Becker et al. [12] developed a comprehensive eight-step procedural model rooted in design science principles. In addition, Solli-Sæther and Gottschalk [18] presented a modeling process for stage models, simultaneously delving into key theoretical aspects of growth stages and addressing theoretical critiques. Among the three main maturity model development frameworks, the approach of De Bruin et al. [17] was selected as the most suitable for the multi-sectoral and cross-domain nature of sustainable urban mobility. Becker et al. [12] proposed a rigorous, design science-based procedure mainly tailored to IT management, which limits its adaptability to domains lacking predefined benchmarks. Solli-Sæther and Gottschalk [18] offered a structured stage-modeling process effective in contexts with clearly defined growth stages, such as e-government, but less flexible in emerging domains. In contrast, De Bruin’s six-phase, domain-independent framework facilitates iterative stakeholder involvement and flexible scoping across sectors, making it particularly well suited to sustainable urban mobility, where maturity criteria span multiple policy areas and remain under development.

A top-down approach is effective when dealing with a multi-sectoral topic that lacks clear indications of maturity criteria. In this context, the primary concern is to define incremental maturity and subsequently determine how to measure it. In the reviewed literature, very few maturity models related to sustainable mobility were found, and research has extended to mobility and smart cities. The identified models were analyzed and assessed in terms of the number of dimensions, sub-dimensions, and maturity levels.

Table 2. Comparison of the reviewed maturity models.

Name of the Model	Number of Dimensions	Number of Sub-Dimensions	Number of Maturity Levels	Study
Maturity Model for Smart Sustainable Communities	3	11	5	[20]
The Maturity Model for Urban Mobility	11	-	5	[21]
Smart Sustainable Cities Maturity Model	3	-	5	[9]
Connectivity Sustainability and Resiliency Maturity Model	3	9	5	[22]
Smart City Development Maturity	6	-	5	[11]
Brazilian Smart City Maturity Model	10	-	5	[23]
C-ITS Maturity Model	8	-	4	[24]
A Maturity Model for Indian Cities	11	-	4	[25]
Smart Cities Maturity Model	6	19	5	[7]
Sustainable and Smart Mobility Maturity Model Based on Smart City Maturity	7	-	5	[19]

presents the reviewed maturity models. In the reviewed literature, only a very limited number of maturity models explicitly address sustainable or smart urban mobility within the broader smart city maturity discourse. Although recent studies, such as that of Budna [19], have begun to conceptualize sustainable and smart mobility maturity, these contributions remain purely conceptual and are not supported by comprehensive operational structures or empirical validation.

As summarized in Table 2, although several maturity models exist, most are either embedded within broader smart city frameworks or address mobility in a fragmented manner. These models do not comprehensively integrate institutional, environmental, social, and multimodal dimensions as a holistic sustainable urban mobility conceptual framework. Therefore, the literature still lacks a dedicated, operational, and empirically validated maturity model focusing specifically on sustainable urban mobility, which constitutes the main gap this study aims to address.

Overall, the literature indicates that while maturity models provide a useful conceptual and diagnostic approach for assessing complex systems, their application to sustainable urban mobility remains limited. Existing studies predominantly focus on smart city contexts or isolated mobility components, lacking an integrated and operational framework tailored to sustainable urban mobility. This state-of-the-art review confirms the need for a holistic, domain-specific, and empirically validated maturity model, which directly motivates the development of the proposed SUM-MM.

3. Materials and Methods

Building on the literature review presented in Section 2, this section consists of three main stages: draft model development, expert consultation and validation, and population of the model. The next section presents testing through a case study. These stages were designed to ensure a systematic, evidence-based, and expert-informed development process, followed by practical validation in a real urban context. The methodological steps followed in this study are summarized in Figure 1.

3.1. Definition of Maturity Levels

Maturity model levels must be precisely defined while maintaining a logical sequence throughout. Level definitions should be created to clarify stage terminology and to provide an overview of the level’s main needs and metrics, particularly those that are unique to that level. Furthermore, levels are cumulative, with higher levels built upon the prerequisites of the lower levels [17]. As in most of the literature reviewed, the SUM-MM has five maturity levels: beginner, where sustainable urban mobility is not yet systematically considered, and practices remain highly fragmented; initial, where the topic is recognized, and implementation remains partial and unsystematic; integrated, where sustainable mobility becomes structurally embedded, and key transport modes and supporting systems are coordinated; managed, where policies and practices are systematically implemented, monitored, and supported by institutionalized governance; and mature, where sustainable mobility is fully institutionalized, technologically and organizationally well-integrated, and continuously improved through evidence-based management. Brief, one-sentence descriptions of the five maturity levels are provided here to clarify the conceptual logic of the model; detailed level definitions are systematically developed later in Section 3.

3.2. Dimension Extraction

De Bruin et al. [17] proposed a method that facilitates more detailed assessments of complex issues. This approach involves adding sub-dimensions to assess various specific aspects within a complex structure. The model can be broken down into dimensions and sub-dimensions. Using this layered model, a city can gain deeper insight into strengths and weaknesses within a dimension or sub-dimension, facilitating the targeting of specific improvement strategies and more efficient resource allocation. Sustainable urban mobility has impacts on the environment, economy, and society, influenced by planning, organizational efforts, and technological advancements. Furthermore, sustainable urban mobility comprises three primary modes of transport: walking, micromobility, and public transport. Paratransit systems include a range of vehicles, including car-sharing systems, taxis, shuttles, and minibuses. Given the absence of adequate public transport services in developing countries, paratransit systems have evolved into a critical component of urban transport systems [26]. The multimodal integration of transportation modes also needs to be addressed in terms of payment, routes, and schedules. According to these components, the SUM-MM has 3 dimensions and 11 sub-dimensions, as shown in

Table 3. Dimensions and sub-dimensions of the Sustainable Urban Mobility Maturity Model.

Dimensions	Enablers	Sustainability	Transport Modes
Sub-dimensions	Strategic and Spatial Planning	Environment	Walking
	Organization and Human Resources	Economy	Micromobility
	Information and Communication Technologies	Social	Public Transport
			Paratransit Systems
			Multimodal Integration

.

To clarify the conceptual meaning of the proposed structure, the three main dimensions and their eleven sub-dimensions are briefly defined. Enablers are the institutional, organizational, planning, and technological capacities that enable the development and management of sustainable mobility. This includes strategic and spatial planning (integration of mobility strategies into urban development and spatial plans), organization and human resources (governance structures, clearly defined institutional roles, coordination, and expertise), and information and communication technologies (use of digital systems, data collection and interoperability, intelligent and analytics-based mobility management). Sustainability captures the outcomes of the mobility system, namely, environmental (reducing environmental impacts and supporting climate adaptation), economic (financial sustainability, decision-support for investments, and resilience to economic uncertainties), and social (equity, accessibility, inclusion, and continuous monitoring of social outcomes) outcomes. Transport modes relate to the performance, safety, and integration of mobility options available in the city, covering walking (safety, accessibility, continuity, and comfort), micromobility (infrastructure, regulations, safe operation, and integration), public transport (coverage, service quality, data-based management, and low/zero-emission fleets), paratransit systems (regulation; centralized management; inspection; environmentally friendly and accessible fleets; and integration with other modes, particularly relevant in developing contexts), and multimodal integration (payment, physical, and timetable integration supported by transfer hubs enabling seamless connections).

Draft definitions of the maturity levels of the 11 sub-dimensions were developed by the authors based on their professional expertise. To strengthen the foundation of this framework, dimensions and sub-dimensions were aligned with widely used international references. The EU’s SUMP Guidelines emphasize the integrated development of all modes with the governance [3], planning, and monitoring pillars, which is consistent with the transport modes and enablers dimensions. Additional international frameworks, the UN-Habitat report [27], and the ISO 37120 [28] indicators for city services and quality of life also emphasize the enablers and sustainability dimensions, reinforcing the comprehensiveness of the SUM-MM’s 3-dimensional, 11-sub-dimensional structure.

For each sub-dimension, the definitions of the lowest (Level 1: beginner) and highest (Level 5: mature) maturity levels are first identified. Subsequently, Levels 2 to 4 are defined as intermediate stages between these two extremes [21]. Maturity level definitions are descriptive, stating what should be accessible at each maturity level, rather than prescriptive, explaining how to attain each maturity level. As a result, the definitions are transformed into questions to which city administrators of sustainable urban mobility need to provide objective responses [22]. Determining the maturity level for each sub-dimension helps to prepare these assessment questions. The questions ensure that the maturity levels are more clearly understood by the target audience and provide a strategic target for it. A structured questionnaire that includes a set of closed-ended questions with predetermined response options will be used for data collection. Response options were also prepared in line with maturity levels. This is a highly organized and standardized way to gather responses, making them easier to interpret [29]. Finally, draft definitions of maturity levels for the sub-dimensions and draft questions (with their 5 maturity level draft responses) were developed by the authors based on their professional expertise. Once the draft definitions and questions used to determine the sub-dimensions were developed, it was necessary to populate and validate them through exploratory research methods (e.g., focus groups, expert opinions, the nominal group technique, the Delphi technique).

3.3. Expert Opinions Method

Choosing the most suitable method depends on the individuals participating in model creation and the resources accessible to the development team [12,17]. Since sustainable urban mobility is a multi-sectoral field, expert opinions were preferred in this study. To evaluate the model, an online survey was conducted with 15 experts from different sectors (academia: 2, private sector: 6, and public sector: 7). This distribution shows that experts contributed to the study with theoretical knowledge, practical experience, and regulatory perspective. The following criteria were considered in selecting participants: having experience in the fields of transportation planning, intelligent transportation systems, sustainable mobility, or multimodal integration; being involved in municipalities, transportation consultancy firms, academic research, or private sector projects. In addition, experts were required to have a minimum of five years of professional experience, ensuring sufficient subject matter expertise.

The questionnaire was prepared on the JotForm platform, and an online link https://www.jotform.com/form/242983666257067 (accessed on 29 April 2025) was shared with experts to gather opinions. In the questionnaire, experts were provided with the existing maturity model and asked to evaluate the 11 sub-dimensions with free-form text responses. Each expert was asked to select at least three sub-dimensions and provide feedback on the maturity levels and assessment questions. The number of experts’ preferred sub-dimensions is as follows: micromobility: 9; public transport: 6, multimodal integration: 6, strategic and spatial planning: 4, information and communication technologies: 4, economy: 4, organization and human resources: 3, Social: 3, environment: 3, walking: 3, paratransit systems: 0. This distribution shows that the experts were particularly focused on the areas of micromobility, public transport and multimodal integration. In contrast, no experts provided feedback on the paratransit systems sub-dimension. Although expert feedback was obtained for almost all sub-dimensions, experts were not required to evaluate every component of the model; instead, they were encouraged to respond only to the areas in which they felt professionally competent. Since paratransit systems are not widely institutionalized in many of the cities represented by the participants, none of the experts selected this sub-dimension. This limitation is acknowledged, and future applications of the SUM-MM in cities with well-established paratransit systems are recommended to strengthen the validity of this component.

The maturity model was updated in line with expert opinions, making the model clearer, more systematic, and more applicable. Transitions between levels have been more clearly defined, evaluation criteria have been elaborated, and ambiguous statements have been simplified. In addition, maturity levels and questions were made more consistent to ensure that maturity was determined through the responses to the questions. However, to keep the focus of the model on sustainable mobility and to limit the number of questions, some of the experts’ suggestions for adding questions or areas were not implemented. The contribution of expert opinions in each sub-dimension is explained below.

3.3.1. Strategic and Spatial Planning

Experts emphasized that strategic and spatial plans follow different processes and legal frameworks and should be evaluated separately. Accordingly, the model was updated to make these differences explicit. The unclear scope of strategic plans was clarified by specifying their focus on transport policies and highlighting the limited integration of sustainable mobility in spatial plans. Expert feedback also led to the inclusion of the nature and stages of stakeholder participation in the evaluation. Furthermore, we emphasized the importance of defining sustainable mobility policies with performance indicators in strategic plans and monitoring their implementation in spatial plans. These updates enabled the model to assess strategic and spatial planning processes more realistically and expanded the evaluation criteria for a comprehensive analysis.

3.3.2. Organization and Human Resources

Updates clarified how organizational structures and human resources support sustainable mobility. Experts emphasized making level distinctions clearer by detailing job descriptions, interdepartmental integration, and stakeholder collaboration. The model now shows how internal and external collaboration evolves across maturity levels and highlights the role of citizen participation in continuous improvement. Performance measurement and monitoring mechanisms were incorporated into governance structures. Although one expert suggested separately evaluating private sector and academic interactions, these were included within general collaborations due to the local government’s focus. Overall, this sub-dimension is reframed as dynamic processes involving participation, collaboration, and ongoing development.

3.3.3. Information and Communication Technologies

Updates addressed specific shortcomings and clarified distinctions between maturity levels in line with expert feedback. The transition from Level 1 to Level 2 was seen as unclear, so the scope of systems based on manual data entry was elaborated to better define it. In response to suggestions about open data, Level 3 now highlights compliance with data standards, while Level 5 more clearly describes the integration of open data sharing into continuous improvement processes. The experts also proposed incorporating data standards as maturity criteria (such as GTFS and GBFS). However, due to the general framework of the model, these standards are not directly integrated but instead expressed as data sharing standards. In Questions 1 and 2, definitions were revised to clarify the meaning of “integrated systems” for respondents of the model. In addition, we clarified the level of integration of decision support systems and data analytics in sustainable mobility policies.

3.3.4. Environment

Based on the expert feedback, several updates were made to the environmental dimension of the maturity model. First, the notion of “mitigation” was deemed insufficient, prompting the integration of the “mitigation and adaptation” approach. This expanded the model to include not only emission and pollution reduction but also strategies for adapting to environmental change. At Level 5, the integration of environmental policies was expanded to emphasize both the sustainability of urban mobility and the avoidance of negative transport impacts from environmental infrastructure improvements. At the question level, the scope of environmental impacts was broadened by adding explicit references to “fossil fuel use” and providing clearer definitions. Environmental data collection and analysis levels were restructured to include measurable indicators such as citywide air quality and transport-related emissions. Although suggestions were made to include separate questions on low-emission zones, public transport integration, and micromobility, these have not yet been implemented due to the need to limit the model’s scope. These updates reflect that the model now evaluates not only how cities reduce environmental impacts, but also how they adapt to changing environmental conditions.

3.3.5. Economy

Expert feedback in the economic dimension helped to distinguish financial sustainability from broader economic impacts, resulting in a more comprehensive model. Financial sustainability was introduced as a distinct component, and resilience to financial crises was strengthened by including circular economy principles at Level 5. Thus, economic sustainability is assessed not only in terms of financial balance but also in long-term urban economic resilience. Questions were expanded to reflect household economy, business activity, and general economic structure. Freight transport and public transport costs were addressed separately in Question 3. Experts also proposed including revenue sources beyond user fees—such as advertising and investment—in financial models. Accordingly, Level 5 was revised to reflect the need for diversified revenue strategies. These changes allow the model to address economic sustainability in public financing and broader resilience frameworks.

3.3.6. Social

The definition of “social groups” was expanded to include people with disabilities, the elderly, children, parents with strollers, and students. In Level 3, solutions implemented in specific areas were clarified as “pilot projects.” To distinguish Levels 4 and 5, Level 4 emphasizes citywide physical accessibility, while Level 5 includes not only physical access but also participation of social groups in decision-making and the existence of monitoring and control mechanisms. Levels 1 and 2 were refined to show that Level 1 includes no solutions, while Level 2 covers only the planning stage. Although experts suggested adding questions on affordability and public awareness, these have not yet been integrated to maintain the consistency of the model. These updates created a more holistic model framework by incorporating not only physical accessibility but also participation, awareness, and affordability into social inclusion.

3.3.7. Walking

In addition to the presence of pedestrian zones, quality criteria such as sidewalk width, condition, and comfort features (e.g., street furniture and greenery) were introduced. At Level 2, clarity was added regarding accessibility and safety, with an emphasis on physical adequacy and compliance with standards. In Level 5, the unclear phrase “all social needs” was specified to include education, healthcare, shopping, and recreation. The scope of the questions was expanded to emphasize accessibility for people with disabilities and safety considerations. The terminology was revised to distinguish between “limited” and “comprehensive” pedestrianization and traffic calming initiatives. To avoid ambiguity in planning terminology, expressions regarding urban plans were clarified. Additionally, the importance of raising awareness about pedestrian zones was reflected in the revised evaluation indicators.

3.3.8. Micromobility

Ambiguities regarding the prevalence of bicycle lanes and infrastructure were addressed by adding “in specific areas” to Level 2. Level 3 highlighted infrastructure clustering and early integration with other modes. At Level 4, the role of micromobility in first- and last-mile connections was added. A non-universal “10% of trips” indicator was replaced with general language about citywide usage and modal integration. Security and usage criteria were clarified, and integration with public transport and other modes was emphasized. Legal and operational regulations were defined more clearly across maturity levels. Questions were expanded to enhance measurability, including a new question on regulations supporting safe and integrated use. These updates allowed micromobility to be evaluated comprehensively across the infrastructure, usage, safety, and integration dimensions.

3.3.9. Public Transport

Level 3 stated that “passengers are informed,” but it was unclear what kind of information they could access. Therefore, the content has been elaborated and the role of real-time information systems emphasized. Level 5 was refined to highlight a modal shift from private vehicles to public transport, not only for long trips but also for short ones. Regarding fleet sustainability, the distinction between Level 4 and Level 5 was clarified by requiring not only low or zero-emission vehicles but also broader environmental sustainability compliance requirements. The model now includes the requirement for stops and stations to be accessible, ensuring accessibility assessments extend beyond vehicles.

Questions and maturity levels related to data collection, analysis, and planning were elaborated to clarify how public transport data is utilized, emphasizing service optimization and the use of data-driven dynamic management systems, particularly at Level 5. Elements such as punctuality, reliability, and operational speed are now considered integral to public transport service quality. In the previous model, the question of “the environmental and social sustainability of vehicles” only addressed vehicle accessibility and emissions. Based on expert feedback, it now also includes the accessibility of stops and stations. Questions related to service quality now holistically address aspects such as service frequency, vehicle occupancy, waiting time, travel time, passenger information, and safety.

These updates have made the public transport maturity model and evaluation questions more comprehensive in terms of service quality, sustainability, data management, and inclusiveness while further clarifying maturity level distinctions and strengthening the role of data-driven decision-making in transport planning.

3.3.10. Multimodal Integration

At Level 1, the absence of integration infrastructure has been more explicitly stated. The differences between Level 2 and Level 3 have been clarified, highlighting that Level 2 involves only payment system integration, while Level 3 includes the physical proximity of lines, improved transfer times, and integration of passenger information systems. At Level 4, timetable and physical integration are jointly considered with additional details to enhance transfer times and passenger guidance. At Level 5, the full integration of the MaaS (Mobility as a Service) model into all transport services is emphasized, creating a seamless network through coordinated transfer hubs and timetable synchronization.

Types of integration have been more clearly defined: physical integration covers route and station positioning and access via walking and micromobility; operational integration addresses timetable coordination and scheduling; and user-centered integration covers payment and passenger information systems. Elements such as trip planning, real-time information access, and multimodal guidance have been incorporated into the integration levels.

Additionally, the integration of micromobility with public transport, the importance of data sharing, and open data standards have been emphasized to enhance integration. The evolving role of MaaS has been explained, extending beyond payment to route planning, arrival time estimation, and facilitating seamless transfers. With these updates, integration types have been clarified, and passenger experience elements are addressed more inclusively within the model.

The revised definitions of maturity levels for each sub-dimension (Table 4, Table 5, Table 6, Table 7, Table 8, Table 9, Table 10, Table 11, Table 12, Table 13 and Table 14), together with the complete SUM-MM framework and calculation tool, are provided in the Supplementary Materials (SUM-MM Excel tool).

Table 4 presents the maturity levels defined for the strategic and spatial planning sub-dimension. These levels describe how sustainable mobility considerations evolve from being completely absent in planning processes to becoming fully integrated into strategic and spatial plans.

Table 4. Strategic and spatial planning maturity levels.

Beginner	Initial	Integrated	Managed	Mature
Sustainable mobility is not taken into account in strategic and spatial plans.	In strategic plans, sustainable mobility is considered a general heading that only refers to transportation policies. In spatial plans, sustainable mobility is not fully integrated with spatial decisions; individual solutions are offered in certain regions.	In some strategic plans, sustainable mobility is addressed at the level of objective, target, and action. In spatial plans, some of the plans include integrated decisions regarding sustainable mobility.	In strategic plans, a holistic sustainable mobility strategy is defined with action and performance indicators. Sustainable mobility strategies have begun to be implemented in different spatial plans.	In all strategic plans, sustainable mobility policies are implemented, determined with the participation of citizens and stakeholders, and integrated in all dimensions. Sustainable mobility decisions are implemented in all spatial plans and monitored regularly.

Table 4. Strategic and spatial planning maturity levels.

Beginner	Initial	Integrated	Managed	Mature
Sustainable mobility is not taken into account in strategic and spatial plans.	In strategic plans, sustainable mobility is considered a general heading that only refers to transportation policies. In spatial plans, sustainable mobility is not fully integrated with spatial decisions; individual solutions are offered in certain regions.	In some strategic plans, sustainable mobility is addressed at the level of objective, target, and action. In spatial plans, some of the plans include integrated decisions regarding sustainable mobility.	In strategic plans, a holistic sustainable mobility strategy is defined with action and performance indicators. Sustainable mobility strategies have begun to be implemented in different spatial plans.	In all strategic plans, sustainable mobility policies are implemented, determined with the participation of citizens and stakeholders, and integrated in all dimensions. Sustainable mobility decisions are implemented in all spatial plans and monitored regularly.

Table 5 presents the maturity levels defined for the organization and human resources sub-dimension. These levels reflect the evolution from the absence of any dedicated organizational structure or expertise on sustainable mobility to a mature governance framework in which roles are clearly defined, performance is monitored, stakeholder collaboration is ensured, and institutional capacity is continuously strengthened through training and citizen feedback.

Table 5. Organization and human resources maturity levels.

Beginner	Initial	Integrated	Managed	Mature
No unit or expert in human resources exists related to sustainable mobility.	There are human resources specialized in sustainable mobility, but there is no responsible unit. The responsible person is open to improvement in sustainable mobility.	Duties in units related to sustainable mobility are clearly determined, and the expert human resources in charge work integrated with other units.	There is a governance structure in which units related to sustainable mobility are included, stakeholders work together, the roles and responsibilities of the units are defined, and performance is measured and monitored.	In the governance structure related to sustainable mobility, citizens are included in decision-making processes, and services and processes are constantly improved with feedback from citizens. The knowledge of experts is supported by continuous training and capacity-building activities.

Table 5. Organization and human resources maturity levels.

Beginner	Initial	Integrated	Managed	Mature
No unit or expert in human resources exists related to sustainable mobility.	There are human resources specialized in sustainable mobility, but there is no responsible unit. The responsible person is open to improvement in sustainable mobility.	Duties in units related to sustainable mobility are clearly determined, and the expert human resources in charge work integrated with other units.	There is a governance structure in which units related to sustainable mobility are included, stakeholders work together, the roles and responsibilities of the units are defined, and performance is measured and monitored.	In the governance structure related to sustainable mobility, citizens are included in decision-making processes, and services and processes are constantly improved with feedback from citizens. The knowledge of experts is supported by continuous training and capacity-building activities.

Table 6 presents the maturity levels for the information and communication technologies (ICTs) sub-dimension. These levels demonstrate the transition from a situation in which ICTs are not used at all in sustainable mobility to a mature stage where advanced digital systems, artificial intelligence-based solutions, and interoperable data infrastructures support decision-making, enable integration with other systems, and are continuously improved through feedback and open data practices.

Table 6. Information and communication technologies maturity levels.

Beginner	Initial	Integrated	Managed	Mature
Information and communication technologies (ICTs) are not used at all in sustainable mobility.	In sustainable mobility, information and communication technologies (IoT, artificial intelligence, etc.) are used only in certain areas and in singular solutions based on manual data entry.	In sustainable mobility, mobility data collected and integrated to certain standards has become interoperable with integrated systems.	In sustainable mobility, different infrastructure and mobility data are analyzed with innovative technologies to provide decision support to local governments.	Autonomous systems and artificial intelligence-based solutions have been developed for sustainable mobility, and processes are constantly improved with feedback from the systems and citizens. Data is shared as open data in accordance with certain standards.

Table 6. Information and communication technologies maturity levels.

Beginner	Initial	Integrated	Managed	Mature
Information and communication technologies (ICTs) are not used at all in sustainable mobility.	In sustainable mobility, information and communication technologies (IoT, artificial intelligence, etc.) are used only in certain areas and in singular solutions based on manual data entry.	In sustainable mobility, mobility data collected and integrated to certain standards has become interoperable with integrated systems.	In sustainable mobility, different infrastructure and mobility data are analyzed with innovative technologies to provide decision support to local governments.	Autonomous systems and artificial intelligence-based solutions have been developed for sustainable mobility, and processes are constantly improved with feedback from the systems and citizens. Data is shared as open data in accordance with certain standards.

Table 7 presents the maturity levels for the environment sub-dimension. These levels demonstrate the progression from a stage where no environmental actions are considered in relation to urban mobility to a mature stage where integrated citywide policies and practices systematically reduce environmental impacts and support climate adaptation.

Table 7. Environment maturity levels.

Beginner	Initial	Integrated	Managed	Mature
There are no actions in the plans to reduce environmental impacts (greenhouse gas emissions, air pollution, noise pollution, fossil fuel use) caused by urban mobility and to adapt to climate change.	The plans include actions to reduce environmental impacts caused by urban mobility and adapt to climate change.	There are integrated practices (monitoring environmental quality, zero-emission vehicles, promotion of non-motorized mobility, etc.) to reduce environmental impacts caused by urban mobility and adapt to climate change.	Improvements in the environmental quality of the city center have been achieved with integrated solutions within the scope of the Low Emission Zone declared in the city center. The use of clean fuel and sustainable mobility systems is supported.	Improvements in environmental quality have been achieved throughout the city with integrated policies and solutions aimed at reducing environmental impacts caused by urban mobility and adapting to climate change.

Table 7. Environment maturity levels.

Beginner	Initial	Integrated	Managed	Mature
There are no actions in the plans to reduce environmental impacts (greenhouse gas emissions, air pollution, noise pollution, fossil fuel use) caused by urban mobility and to adapt to climate change.	The plans include actions to reduce environmental impacts caused by urban mobility and adapt to climate change.	There are integrated practices (monitoring environmental quality, zero-emission vehicles, promotion of non-motorized mobility, etc.) to reduce environmental impacts caused by urban mobility and adapt to climate change.	Improvements in the environmental quality of the city center have been achieved with integrated solutions within the scope of the Low Emission Zone declared in the city center. The use of clean fuel and sustainable mobility systems is supported.	Improvements in environmental quality have been achieved throughout the city with integrated policies and solutions aimed at reducing environmental impacts caused by urban mobility and adapting to climate change.

Table 8 presents the maturity levels for the economy sub-dimension. These levels show the transition from a stage where the economic impacts and financial sustainability of urban mobility are not considered to a mature stage where urban mobility systems are financially sustainable, supported by strong decision-making tools, and resilient to economic crises and uncertainties.

Table 8. Economy maturity levels.

Beginner	Initial	Integrated	Managed	Mature
The economic impacts and financial sustainability of urban mobility are not taken into account.	Alternative financing methods are used to ensure the financial sustainability of urban mobility.	Contribution to the economy of the city is made by improving business trips and freight mobility in the city.	Investment decisions for urban mobility projects are made with the help of economic and financial decision support tools that include feasibility and cost–benefit analyses.	Necessary structures have been established to make urban mobility financially sustainable, and urban mobility has become resistant to national/international economic crises and uncertainties.

Table 8. Economy maturity levels.

Beginner	Initial	Integrated	Managed	Mature
The economic impacts and financial sustainability of urban mobility are not taken into account.	Alternative financing methods are used to ensure the financial sustainability of urban mobility.	Contribution to the economy of the city is made by improving business trips and freight mobility in the city.	Investment decisions for urban mobility projects are made with the help of economic and financial decision support tools that include feasibility and cost–benefit analyses.	Necessary structures have been established to make urban mobility financially sustainable, and urban mobility has become resistant to national/international economic crises and uncertainties.

Table 9 presents the maturity levels for the social sub-dimension. These levels illustrate progression from a stage where the needs of different social groups are not considered in urban mobility to a mature stage where the accessibility, inclusion, participation, affordability, and safety needs of all social groups are addressed citywide and supported by continuous monitoring and control mechanisms.

Table 9. Social maturity levels.

Beginner	Initial	Integrated	Managed	Mature
The needs of social groups (disabled people, elderly people, children, parents using baby strollers, students, etc.) are not taken into account in urban mobility.	Although there are plans for urban mobility needs specific to social groups, they have not been implemented.	Pilot implementations are carried out, and solutions are developed to meet the needs of social groups in certain regions.	With the accessibility of pedestrian paths, public transport vehicles, and stops and stations throughout the city, barrier-free door-to-door mobility is ensured.	In urban mobility, the quality of life has been increased by meeting the accessibility, inclusion, participation, affordability, and security needs of all social groups, and continuous monitoring and control mechanisms have been established.

Table 9. Social maturity levels.

Beginner	Initial	Integrated	Managed	Mature
The needs of social groups (disabled people, elderly people, children, parents using baby strollers, students, etc.) are not taken into account in urban mobility.	Although there are plans for urban mobility needs specific to social groups, they have not been implemented.	Pilot implementations are carried out, and solutions are developed to meet the needs of social groups in certain regions.	With the accessibility of pedestrian paths, public transport vehicles, and stops and stations throughout the city, barrier-free door-to-door mobility is ensured.	In urban mobility, the quality of life has been increased by meeting the accessibility, inclusion, participation, affordability, and security needs of all social groups, and continuous monitoring and control mechanisms have been established.

Table 10 presents the maturity levels for the walking sub-dimension. These levels show the progression from a situation where pedestrian safety and accessibility are not considered in infrastructure planning to a mature stage where a qualified, citywide pedestrian network is established, accessibility standards are ensured, and the pedestrian environment is continuously improved to encourage walking.

Table 10. Walking maturity levels.

Beginner	Initial	Integrated	Managed	Mature
Safety and accessibility criteria are not taken into account in human-oriented pedestrian transportation infrastructure plans and implementations.	There are plans to improve the safety and accessibility of pedestrian paths and sidewalks, but these solutions have not been adequately implemented.	Pedestrian paths and sidewalks generally have sufficient width, compliance with accessibility standards, and physical continuity for pedestrians to use them safely and comfortably.	Necessary precautions have been taken, and inspections have been implemented at an adequate level to ensure the safety of pedestrian paths and sidewalks and to increase their accessibility for all users.	A qualified and holistic pedestrian network has been created throughout the city, safety and accessibility standards have been ensured, and comfort-enhancing elements such as urban furniture and planting that encourage pedestrian mobility are widely implemented.

Table 10. Walking maturity levels.

Beginner	Initial	Integrated	Managed	Mature
Safety and accessibility criteria are not taken into account in human-oriented pedestrian transportation infrastructure plans and implementations.	There are plans to improve the safety and accessibility of pedestrian paths and sidewalks, but these solutions have not been adequately implemented.	Pedestrian paths and sidewalks generally have sufficient width, compliance with accessibility standards, and physical continuity for pedestrians to use them safely and comfortably.	Necessary precautions have been taken, and inspections have been implemented at an adequate level to ensure the safety of pedestrian paths and sidewalks and to increase their accessibility for all users.	A qualified and holistic pedestrian network has been created throughout the city, safety and accessibility standards have been ensured, and comfort-enhancing elements such as urban furniture and planting that encourage pedestrian mobility are widely implemented.

Table 11 presents the maturity levels for the micromobility sub-dimension. These levels describe the transition from a situation where micromobility is not considered in plans, and there are no regulations to a mature stage where micromobility is widely used across the city, legally and operationally regulated, fully integrated with other transport modes, and continuously improved to ensure safe and effective use.

Table 11. Micromobility maturity levels.

Beginner	Initial	Integrated	Managed	Mature
Micromobility (bicycle, scooter) transportation is not taken into account in plans and implementations, and there are no regulations for micromobility.	For micromobility, there are bicycle paths, parking areas, and micromobility sharing systems with limited interconnection in certain regions, and they are not widespread throughout the city. Awareness studies on the use of micromobility are limited; legal and operational regulations have been planned but have not yet been implemented.	Awareness studies are carried out to increase the use of micromobility, and legal and operational regulations are partially implemented for safe use. Micromobility infrastructure and usage are concentrated in certain regions, and the process of integration with other modes has begun.	Micromobility is used regularly for daily home–work, home–school trips. Legal and operational regulations are in place for the safe use of micromobility, with additional regulations supporting the integration of micromobility with the entire transportation system as a first- and last-mile connection.	Micromobility is widely used throughout the city and is fully integrated with other modes of transportation. All legal and operational regulations for the safe and integrated use of micromobility are fully implemented and constantly improved.

Table 11. Micromobility maturity levels.

Beginner	Initial	Integrated	Managed	Mature
Micromobility (bicycle, scooter) transportation is not taken into account in plans and implementations, and there are no regulations for micromobility.	For micromobility, there are bicycle paths, parking areas, and micromobility sharing systems with limited interconnection in certain regions, and they are not widespread throughout the city. Awareness studies on the use of micromobility are limited; legal and operational regulations have been planned but have not yet been implemented.	Awareness studies are carried out to increase the use of micromobility, and legal and operational regulations are partially implemented for safe use. Micromobility infrastructure and usage are concentrated in certain regions, and the process of integration with other modes has begun.	Micromobility is used regularly for daily home–work, home–school trips. Legal and operational regulations are in place for the safe use of micromobility, with additional regulations supporting the integration of micromobility with the entire transportation system as a first- and last-mile connection.	Micromobility is widely used throughout the city and is fully integrated with other modes of transportation. All legal and operational regulations for the safe and integrated use of micromobility are fully implemented and constantly improved.

Table 12 presents the maturity levels for the public transport sub-dimension. These levels show the transition from unplanned, low-quality, and weakly monitored public transport services to a mature stage where public transport is safe, inclusive, affordable, and comfortable; highly integrated with the overall transportation system; supported by data-driven management; and predominantly operated with low- or zero-emission fleets.

Table 12. Public transport maturity levels.

Beginner	Initial	Integrated	Managed	Mature
Public transport services are unplanned, in-vehicle equipment is inadequate, service quality is low, and environmental–social sustainability cannot be achieved. Public transport data is not collected or is collected to a limited extent.	There are electronic fare collection systems in public transport vehicles. Part of the fleet consists of environmentally friendly and disabled accessible vehicles. Public transport data is collected at a basic level but is not analyzed.	With public transport fleet management, vehicle tracking and vehicle and driver assignments are performed, and passengers are informed instantly. The majority of the fleet is environmentally friendly and accessible. Public transport data is analyzed and used for service improvements.	The public transport system is safe, inclusive, affordable, and comfortable. The majority of the fleet is low or zero emission. Line planning and optimization are carried out with data analytics.	Public transport service quality is high and integrated with the entire transportation system. It covers a large part of the trips by reducing the use of private vehicles. It is a constantly improving system that ensures seamless travel, with the entire fleet having low or zero emissions.

Table 12. Public transport maturity levels.

Beginner	Initial	Integrated	Managed	Mature
Public transport services are unplanned, in-vehicle equipment is inadequate, service quality is low, and environmental–social sustainability cannot be achieved. Public transport data is not collected or is collected to a limited extent.	There are electronic fare collection systems in public transport vehicles. Part of the fleet consists of environmentally friendly and disabled accessible vehicles. Public transport data is collected at a basic level but is not analyzed.	With public transport fleet management, vehicle tracking and vehicle and driver assignments are performed, and passengers are informed instantly. The majority of the fleet is environmentally friendly and accessible. Public transport data is analyzed and used for service improvements.	The public transport system is safe, inclusive, affordable, and comfortable. The majority of the fleet is low or zero emission. Line planning and optimization are carried out with data analytics.	Public transport service quality is high and integrated with the entire transportation system. It covers a large part of the trips by reducing the use of private vehicles. It is a constantly improving system that ensures seamless travel, with the entire fleet having low or zero emissions.

Table 13 presents the maturity levels for the paratransit systems sub-dimension. These levels illustrate the evolution from irregular, unplanned, and weakly regulated paratransit services to a mature stage where routes and vehicles are centrally managed, environmentally friendly and accessible fleets are ensured, continuous inspection and feedback mechanisms are in place, and paratransit is fully integrated with other modes of transportation.

Table 13. Paratransit systems maturity levels.

Beginner	Initial	Integrated	Managed	Mature
Paratransit systems are irregular and unplanned. Routes and service standards are unclear. There are no inspection and regulatory mechanisms.	Routes and service standards have been established, but implementation is limited. Route regulations and service standards have been established in some areas, but they are not widespread throughout the city.	Vehicle tracking and camera systems have become widespread, and routes are planned centrally. Compliance with the standards set in paratransit systems is increasing, but a significant part of the fleet still operates with old systems.	Fleet management is performed centrally, and vehicles and routes are inspected. The majority of the paratransit fleet is environmentally friendly and accessible. Routes and flight frequencies are optimized according to central planning.	All routes in paratransit systems are managed centrally, and the system is improved with feedback from continuous inspections. All vehicles are made environmentally friendly and accessible, integrated with other modes of transportation.

Table 13. Paratransit systems maturity levels.

Beginner	Initial	Integrated	Managed	Mature
Paratransit systems are irregular and unplanned. Routes and service standards are unclear. There are no inspection and regulatory mechanisms.	Routes and service standards have been established, but implementation is limited. Route regulations and service standards have been established in some areas, but they are not widespread throughout the city.	Vehicle tracking and camera systems have become widespread, and routes are planned centrally. Compliance with the standards set in paratransit systems is increasing, but a significant part of the fleet still operates with old systems.	Fleet management is performed centrally, and vehicles and routes are inspected. The majority of the paratransit fleet is environmentally friendly and accessible. Routes and flight frequencies are optimized according to central planning.	All routes in paratransit systems are managed centrally, and the system is improved with feedback from continuous inspections. All vehicles are made environmentally friendly and accessible, integrated with other modes of transportation.

Table 14 presents the maturity levels for the multimodal integration sub-dimension. These levels illustrate the transition from a situation where there is no integration between transport modes and transfers are difficult to a mature stage where payment, physical, and timetable integration have been fully achieved; transfer hubs support seamless connections; and access between modes is ensured within short walking or micromobility distances.

Table 14. Multimodal integration maturity levels.

Beginner	Initial	Integrated	Managed	Mature
There is no integration between transport modes throughout the city. Transferring between modes is difficult, transfer times are long, and transport links are irregular.	Payment integration is provided in all modes of public transport. A single transportation card can be used in all public transport vehicles and some paratransit system vehicles. However, the physical integration of the transportation network is limited, and the transfer time is still long.	The physical integration of the transportation network has begun. The stops and stations of public transport lines are partially closer, and the transfer time is at an acceptable level. Access to public transport is partially possible through walking and micromobility. Payment and passenger information integration is partially provided or available in certain modes.	With the timetable integration, the physical integration of the transportation network has been improved. Timetables have been harmonized, and transfer times have been shortened. Access to public transport is often possible by walking and micromobility. Payment and passenger information integration is fully provided and valid in all modes.	MaaS (Mobility as a Service) application is used in all transportation services. Payment integration, physical integration of the transportation network, and timetable integration have been fully achieved. Transfer hubs, which include all modes of transportation, are located within a 15 min walking or micromobility distance.

Table 14. Multimodal integration maturity levels.

Beginner	Initial	Integrated	Managed	Mature
There is no integration between transport modes throughout the city. Transferring between modes is difficult, transfer times are long, and transport links are irregular.	Payment integration is provided in all modes of public transport. A single transportation card can be used in all public transport vehicles and some paratransit system vehicles. However, the physical integration of the transportation network is limited, and the transfer time is still long.	The physical integration of the transportation network has begun. The stops and stations of public transport lines are partially closer, and the transfer time is at an acceptable level. Access to public transport is partially possible through walking and micromobility. Payment and passenger information integration is partially provided or available in certain modes.	With the timetable integration, the physical integration of the transportation network has been improved. Timetables have been harmonized, and transfer times have been shortened. Access to public transport is often possible by walking and micromobility. Payment and passenger information integration is fully provided and valid in all modes.	MaaS (Mobility as a Service) application is used in all transportation services. Payment integration, physical integration of the transportation network, and timetable integration have been fully achieved. Transfer hubs, which include all modes of transportation, are located within a 15 min walking or micromobility distance.

The maturity score corresponds to the maturity levels and is defined as follows: beginner (1), initial (2), integrated (3), managed (4), mature (5). These scores are applied to questions, sub-dimensions, dimensions, and the overall model. During the implementation of the model, users respond to all questions with predefined options in line with maturity levels. For each question, users obtain scores from the minimum beginner (1) to the maximum mature (5), and sub-dimension maturity scores are calculated by averaging the maturity scores of the sub-dimension questions. Dimension maturity level scores are calculated by averaging related sub-dimensions. The final score is calculated by averaging all dimensions.

In the SUM-MM, all questions have equal value in determining the sub-dimension maturity level. Similarly, all sub-dimensions have equal value in determining the maturity level of dimensions, and all dimensions have equal value in determining the maturity level of sustainable mobility. All these components of the SUM-MM should be equally represented, and a deficiency in one component should not be compensated for by another. For this reason, no weighting study was performed on the questions, sub-dimensions, or dimensions.

4. Results

When it comes to test implementation, it is essential to implement the model in organizations independent from those involved in its development [17]. Cities could gain from the potential use of the SUM-MM, and they are capable of applying the model across various entities within urban mobility-related departments. The city selected for testing the model should cover all of its sub-dimensions. Based on the literature review on sustainable urban mobility in Turkish cities, we decided to implement the model in Konya, whose transportation systems are shown in Figure 2. In this study, the SUM-MM was tested within the Konya Metropolitan Municipality.

A face-to-face meeting was held with Konya Metropolitan Municipality sustainable mobility administrators. All questions with predefined response options were discussed with city administrators, and responses were given by consensus. According to consensus responses to the questions, a sub-dimension maturity score was calculated by averaging the maturity scores of sub-dimension questions. The dimension maturity level score was calculated by averaging the related sub-dimensions. The maturity levels of the SUM-MM sub-dimensions and dimensions of Konya are provided in

Table 15. SUM-MM maturity level scores for Konya.

Sub-Dimension	Maturity Score	Dimension	Maturity Score	SUM-MM Final Maturity Score
Strategic and Spatial Planning	2.50	Enablers	4.00	3.27
Organization and Human Resources	5.00
Information and Communication Technologies	4.50
Environment	2.67	Sustainability	2.94
Economy	2.67
Social	3.50
Walking	2.00	Transport Modes	2.87
Micromobility	4.00
Public Transport	4.00
Paratransit Systems	1.67
Multimodal Integration	2.67

.

The overall sustainable urban mobility maturity level of Konya was calculated by averaging all dimensions. The level was 3.27, which corresponds to a maturity level between integrated and managed. The enablers dimension has the highest score (4.00) among the dimensions, and the organization and human resources sub-dimension has the highest score (5.00) among its sub-dimensions. Conversely, the transport modes dimension has the lowest score (2.87) among the dimensions, and the paratransit systems sub-dimension has the lowest score (1.67) among its sub-dimensions.

In Konya, sub-dimension maturity levels are not equally distributed. In the enablers dimension, the maturity of the strategic and spatial planning sub-dimension is low, while the other two sub-dimensions are higher. In the sustainability dimension, the maturity of the social sub-dimension is high, and the other two sub-dimensions are lower, but the maturity level gap is smaller than that of the enablers dimension. In the transport modes dimension, the maturity values of the public transport and micromobility sub-dimensions are high, but the maturity of the other three sub-dimensions is lower. In particular, the difference between the maturity score of the public transport (4.00) and paratransit systems (1.67), which provide public transport services in different modes, is particularly notable in the transport modes dimension. The considerable gap between the highest sub-dimension score (organization and human resources, 5.00) and the lowest (paratransit systems, 1.67) reflects structural and institutional differences within the city’s mobility system. According to the city administrators consulted in this study, this high score can be attributed to the Konya Metropolitan Municipality’s well-established institutional structure, experienced technical staff, and active engagement in national and EU-funded sustainable mobility initiatives. In contrast, consistent with the expert evaluations obtained during the face-to-face meetings, the lower paratransit score reflects the fragmented and largely informal structure of paratransit operations and limited regulatory oversight. This gap also reflects a broader structural issue: whereas organizational structures are relatively well developed, operational practices often lag behind. This disparity illustrates how the model can identify specific weaknesses, supporting targeted policy and investment decisions. Based on the calculated sub-dimension maturity levels, planners can develop their roadmaps, prioritize specific areas, and anticipate the funds needed to upgrade their city to higher maturity levels.

These findings are consistent with Konya’s Sustainable Urban Mobility Plan 2030, which highlights strong governance, planning capacity, and ICT development while also identifying gaps in paratransit and multimodal integration [30]. In contrast, Istanbul represents a megacity context where high demand, institutional complexity, and integration challenges remain significant despite major transport investments [31]. This contrast supports the plausibility of the maturity results and demonstrates the contextual value of the SUM-MM framework.

5. Discussion

Based on professional expertise and validated through expert opinions, this study develops a Sustainable Urban Mobility Maturity Model (SUM-MM) comprising three dimensions and eleven sub-dimensions. The clear and hierarchical identification of components provides a structured framework for assessing sustainable urban mobility maturity. Maturity levels, dimensions, and sub-dimensions were first derived from the literature, then populated and validated with expert feedback, and finally tested in the city of Konya, Türkiye.

In this section, the findings are interpreted in relation to the purpose and structure of the proposed maturity model. The discussion first considers how the model can inform different stakeholder groups and policy domains; reflects on the methodological and structural aspects of the model; and finally addresses applicability, limitations, and future research opportunities. This approach helps to present the results in a clear and coherent manner while linking them to the broader implications of sustainable urban mobility planning.

The defined maturity levels can be used not only to assess the current status, but also to guide policy-making. Predefined response options aligned with maturity levels facilitate analysis and the development of sustainable mobility strategies. The proposed model can support different stakeholder groups in planning, implementing, and evaluating sustainable urban mobility.

Table 16. Stakeholders and Policy Recommendations.

Stakeholders	Policy Recommendations
Local Governments	Identify strong and weak areas, set priorities, and integrate results into SUMPs
National Governments	Use maturity levels to inform targeted policies, funding allocation, and monitoring frameworks
Transport Planners	Support strategic planning, project prioritization, and cross-sectoral coordination
Urban Mobility Operators	Align operations and investments with city maturity targets; address gaps (e.g., integration, accessibility)
Researchers/Consultants	Apply and adapt the model for comparative analysis and further methodological development

summarizes the key stakeholder categories and illustrates how each group may benefit from the model results and related policy recommendations.

The model also has room for improvement and customization regarding the following issues. While the model was being populated, the expert opinions were aggregated so that individual subjectivity would not adversely affect its accuracy. Expert opinions were used to introduce certain assumptions, as determining five maturity levels in a sub-dimension may require making some assumptions within that sub-dimension (for example, payment integration is more prioritized than route and schedule integration in the multimodal integration of transport modes). To make the model more objective, the definitions can be enriched with sustainable urban mobility indicators in the future. Furthermore, the representations of dimensions, sub-dimensions, and questions had equal values when calculating the maturity level in the SUM-MM; however, assigning equal weight to all dimensions and sub-dimensions may not fully reflect their different levels of strategic importance across different cities. Therefore, in future implementations, the model may benefit from the development of a weighting structure informed by empirical evidence, stakeholder priorities, and multi-criteria decision-making techniques, facilitating more context-sensitive and differentiated maturity assessments.

Many sectors affect and are affected by sustainable mobility, and sub-dimensions representing these sectors are present in the model. For the model to be used, information representing the city must be provided in all sub-dimensions. The findings of this test study showed that information should be obtained from a large target audience that can provide information in all sub-dimensions.

The model determines the sustainable urban mobility maturity of a city as a result of sustainable urban mobility service providers’ responses to its questions. It is important to understand the relationship between sustainable urban mobility maturity, which represents the service supply side, and the choices of travelers, which represent the service demand side. The relationship between the maturity level of sustainable urban mobility and the user acceptance of sustainable urban mobility measures represents a promising direction for future research.

Using the model in different cities is expected to help in verifying its generalizability; for example, in a city where there is no paratransit systems dimension, the model must be customized. Since the model framework is structured hierarchically, the model is easy to customize. The continued validity of a model will only be achieved by using and maintaining it over time. However, the heterogeneity of cities—such as differences in size, population, travel behavior, and economic structure—makes it challenging to develop a model that can be uniformly applied to all cities. Although the Konya case study successfully demonstrated the applicability of the proposed model, relying on a single-city validation inevitably limits the generalizability of the findings. Therefore, future applications in cities of different sizes, governance structures, and mobility contexts are essential to further test, refine, and strengthen the robustness of the SUM-MM.

This study has several limitations and constraints. The model captures perceived maturity rather than audited performance metrics, and responses may be influenced by individual perspectives, organizational roles, and the information available to respondents at the time of the survey. Furthermore, the model was tested in a single urban context, limiting its generalizability. Increasing the number of applications in different cities and the diversity of participants in future implementations could help mitigate this issue. Sustainable mobility has many sub-dimensions, and it was challenging to reach both experts who could support model development and participants who could accurately respond to questions across all sub-dimensions, particularly for the paratransit systems sub-dimension, which lacked expert validation and may have affected the reliability of this component. Therefore, although expert- and administrator-based assessments provide valuable contextual insight, they also introduce potential subjectivity. Future implementations of the model should incorporate audited performance indicators and objective datasets—where available—to further reduce bias and strengthen the reliability and evidence-based nature of SUM-MM assessments.

6. Conclusions

This study aimed to develop a Sustainable Urban Mobility Maturity Model that can be applied to cities. A maturity model in the field of sustainable urban mobility has not been found in the literature. Thus, a model was designed by the authors, populated and validated with expert opinions, and tested in a city. The results show that the model can be used to comprehensively evaluate a city in terms of sustainable urban mobility and provide detailed guidance on areas where improvement is needed. Therefore, this model should be used in the current state analysis phase of sustainable urban mobility planning studies. The difficulties encountered in designing and testing the model can be overcome by using it in different cities.

The application of the model to the case of Konya revealed notable differences across dimensions, with higher maturity levels observed in governance- and technology-related enablers, while transport modes—particularly paratransit systems and multimodal integration—showed comparatively lower maturity. These outcomes demonstrate the model’s ability to identify structural imbalances and provide targeted insights for prioritizing sustainable urban mobility interventions. Moreover, the results are in line with Konya’s Sustainable Urban Mobility Plan 2030, which underscores strong governance and planning capacities while pointing to remaining challenges in paratransit systems and multimodal integration.

Beyond providing a structured maturity assessment, the SUM-MM offers a practical decision-support tool that can help cities to prioritize investments, allocate resources more effectively, and monitor progress over time. Future applications of the model in cities with different sizes, governance structures, and mobility contexts are expected to enhance its robustness and contribute to building a more comparable global knowledge base on sustainable urban mobility maturity.