Examining Sustainable Mobility Planning and Design for Smart Urban Development in Metropolitan Areas

Abstract

Meeting the European Green Deal’s goal of climate neutrality by 2050 calls for a 90 percent decrease in emissions from the transportation sector. Thus, there is need to accelerate the shift to more sustainable mobility for integrated and smarter multimodal and intermodal mobility. In European countries, more than 70% of the inhabitants live in metropolitan areas. Achieving low-carbon and more sustainable mobility is important to ensuring sustainable urban infrastructure. However, current mobility planning frameworks do not consider the key factors and strategies that encourage residents to choose sustainable transport modes. Hence, there is a need to identify the most efficient actions that should be employed either in the short or long term to achieve accessible, safe, cost-effective, and green transport systems specifically through the development of sustainable public transportation. Moreover, a paradigm shift is needed to explore the synergy between transportation and its relationship to the city. Accordingly, this article presents an action plan as an approach to assess key strategies needed to foster sustainable and smart mobility planning and design by deploying effective strategies and design solutions that support different green means of transportation for smart urban development. Qualitative data on sustainable mobility planning and design strategies was collected via secondary sources from the literature, and descriptive data analysis was carried out. Findings from this study identify internal and external factors required to promote sustainable multimodal and intermodal mobility based on the city’s transport policies and actions. Implications from this study provide a use case for the technological requirements required for electric mobility planning, design, and system operation for the actualization of sustainable public transportation to improve smart urban development.

1. Introduction

It is now nearly three decades since the concept of sustainable mobility was first proposed in the 1992 European Union (EU) report on the effect of transport on the natural environment [1]. Transportation has a foremost effect not only on the physical form of municipalities but on the livability and quality of man-made and natural environments [2]. Road transportation is one of the main contributors of Greenhouse Gas (GHG) emissions, which lead to climate change and global warming [3]. But promoting the decarbonization of road transportation by employing more green and efficient mobility is a demanding task. As such, municipalities are planning to reduce car use in city centers [4]. The adoption of sustainable mobility services is projected to provide citizens and visitors with the benefits of mobility beyond owning a private car. Sustainable modes of transportation comprise public transportation, walking, and cycling [5]. Sustainable urban mobility planning has been the center of consideration across municipalities. The local environment and the condition of urban spaces are significantly impacted by different mobility modes, ranging from the mass use of private vehicles to “soft mobility” of pedestrian walkways for safe walkability and cycle paths, and also via other modes of public transportation [6,7]. Thus, one of the priorities of transport policy is to improve the overall quality of public transportation, including areas related to accessibility to remote areas, towards a sustainable urban mobility system [8].

Although there are a few unintended consequences of tech-driven mobility solutions, like increased digital surveillance or economic exclusion, evidence from the literature [9,10] reveals that tech-driven mobility solutions foster community-based on-demand electric carpooling, thereby enhancing urban mobility to support environmental friendliness, lower cost, and social well-being for citizens. Thus, several policies and strategies have been suggested for advancing multimodal and intermodal transportation services, mostly by disincentivizing personal vehicle usage and fostering the use of public transportation and active mobility [11]. Prior studies have attempted to improve modal interchange by employing technological enablers for enhancing sustainable mobility services in cities (e.g., cloud services, big data, etc.), emphasizing the interest in research in this area [12]. Moreover, prior studies such as Münster et al. [13] examined how to engage residents in urban design planning by utilizing digital tools considering the state of the art, main challenges, and future approaches. Also, Savithramma et al. [14] explored smart mobility applications within smart cities based on a review of state-of-the-art technologies. There are limited studies that examine the specific factors and strategies to be adopted for improving sustainable mobility planning and design in urban environments. Also, studies grounded in providing user-centric mobility services co-created with the goal of smart urban development in metropolitan areas are limited. Likewise, there is need to support policymakers to improve the synergy between transportation and city policies, as well as sustainable mobility planning and policy decisions as suggested in the literature [12].

Furthermore, there is a need for research that provides a comprehensive, multimodal approach to sustainable mobility planning and design focused beyond transport infrastructure. As such, public participation is necessary for urban development in metropolitan areas to be successfully implemented [15]. Also, there is no adequate approach that facilitates integrated mobility in metropolitan areas [16,17]. Additionally, there is a lack of knowledge about citizens’ perceptions, needs, and requirements or their possible acceptance of sustainable mobility concepts [18]. Therefore, there is a need for an approach such as an action plan or model that supports sustainable mobility planning and design. Such an approach can be used to identify and conceptualize the current public transportation conditions and to explore scenarios to be utilized to actualize smart urban development. Additionally, to fully achieve sustainable mobility, municipalities should employ a seamless and integrated transport system that addresses the mobility needs of citizens and tourists, institutions, and businesses while decreasing dependence on private cars. This also encourages a mobility shift towards public transportation and soft transportation modes such as cycling and walking [19]. Therefore, this study aims to examine the following research questions.

• What is the significance of sustainable mobility services and smart mobility for urban mobility development?
• What are the current mobility planning and design practices employed by municipalities for smart urban development?
• What are the internal and external factors that may impact sustainable mobility planning and design within a metropolitan area?
• What are the strategies and associated elements that impact sustainable mobility planning and design for smart urban development?

To address the aforementioned research questions, this study aims at providing an effective multimodal and intermodal low-carbon means of modal interchange among different territories within a metropolitan area grounded on qualitative data collected from a Systematic Literature Review (SLR). The main objective of this study is to discuss the current mobility planning and design practices, identify the internal and external factors that may impact sustainable mobility planning and design, and finally specify the strategies and associated elements that impact sustainable mobility planning and design for smart urban development. Therefore, this study develops a sustainable mobility planning and design approach. The developed approach comprises hard and soft infrastructure, pricing and regulations, information availability, and the use of public spaces (transport demand) needed by municipalities to facilitate a multimodal modality that supports drivability, cyclability, walkability, and transitability within and across metropolitan areas. Evidence from this study will be relevant for researchers and mobility experts interested in sustainable mobility design and planning with key interest in integrated forms of sustainable mobility. More importantly, findings from this study reveal how governments can support local municipalities to present transition pathways for sustainable mobility towards the target of climate neutrality by 2050. The rest of this paper is organized into six sections: research background, methodology, findings, discussion and implications, and finally a conclusion that outlines the significance of the study.

2. Research Background

2.1. Review of Sustainable Mobility Planning and Design

Several studies from different disciplines have investigated sustainable mobility planning and design in the literature. Among these studies, Morfoulaki and Papathanasiou [20] adopted a multicriteria decision analysis approach for arranging alternative measures for sustainable urban mobility planning. The study considered co-planning and co-creation of future measures taking into account the views of all applicable groups of citizens and stakeholders. Bardal et al. [21] presented strategies for sustainable mobility from the lens of policy design and implementation. The study focused on investigating barriers and solutions for initiating strategies for the transition to more environmentally friendly urban mobility. Moreover, Foltýnová et al. [22] researched different stakeholders’ perspectives regarding sustainable urban mobility. The research aimed to specify the core shared viewpoints on the chosen paths towards green urban mobility. Findings from the study revealed that there is, however, a gap between green mobility research and its application in practice. An earlier study by Gallo and Marinelli [7] reviewed possible actions and policies for sustainable mobility. Findings from the study provide a summarized view of the issues and feasible solutions to improve sustainable mobility.

Guzman et al. [23] studied traffic congestion faced in urban areas and proposed a sustainable mobility plan for private and public organizations. The authors evaluated the modal choice of drivers (motorcycles and cars) relative to a series of individual mobility strategies to be implemented within a city. Another study by Papantoniou et al. [24] designed a sustainable mobility action plan as a sequence of steps to be employed by academia as a strategic guide. The study aimed to provide a template for an action plan that could be adopted mainly by universities to direct mobility planning and implementation. Pisoni et al. [25] evaluated the effect of sustainable city mobility designs based on metropolitan air quality. The authors employed a green urban mobility plan framework across different cities in Europe to design how the parameters they include may influence mobility and emissions within an urban environment. Serrano-López et al. [26] examined policies related to urban sustainable transport planning in a peri-urban city. Evidence from the study revealed how regulations are carried out for urban planning by analyzing the impact of some urban planning parameters employed to stimulate mobility. Wołek [16] explored sustainable mobility planning by considering spatial policy and urban transport. The author presented the process of making transportation in cities greener by considering space metropolization as a challenge to achieving sustainability.

Additionally, Carteni [27] discussed the overall concept of urban sustainable mobility, advocating its feasibility for transport planning. The author highlighted the significance of rational decisions, pointing out that it is of paramount importance to deliberate on rational decisions in transport planning. Hickman et al. [28] researched on how planning can be performed to support sustainable mobility. Based on two case studies, the researchers examined future strategies for urban transport investment strategies assisting in the transition to sustainable mobility to decrease Carbon Dioxide (CO₂₎ emissions in transport. Amoroso et al. [29] presented indicators for measuring sustainable mobility in cities. Evidence from the study provided an analysis of a set of indicators that can contribute to sustainable transport policy deployment in different urban contexts dedicated to social, economic, and environmental dimensions of sustainability in the daily mobility of citizens and urban transport. Huétink et al. [30] proposed initial infrastructure development schemes for sustainable mobility transition. Findings from the study presented an agent-based approach to examine the developmental process for hydrogen-powered vehicles and therefore focused on the role of consumers in this process. Silva and Ribeiro [4] provided integrated planning for municipalities to promote green mobility. The authors explored applicable strategies to govern urban mobility, considering the tradeoff among the targets of environmental sustainability and accessibility in urban spaces.

Although the reviewed studies in this section explored sustainable mobility planning, none of these studies provided a standardized and structured approach to be adopted by municipalities to develop effective and efficient sustainable mobility planning as well as “design strategies” tailored to each city’s needs and characteristics for smart urban transformation. Similarly, there are few that studied the social, technological, economic, and environmental requirements of sustainability for smart urban development. Prior studies reviewed did not adequately consider the technological requirements of sustainable mobility. In addition, none of the studies provided a holistic approach grounded in SLR and case scenario methods. Based on this knowledge gap, this article proposes an action plan as an approach to assess key strategies and factors (in RQ ii & iii) to promote sustainable mobility planning and “design” in metropolitan areas by mainly considering the technological requirements for smart urban development.

2.2. Existing Approaches for Urban Mobility Planning and Design

This subsection reviews existing approaches for participation and e-participation from the perspective of urban mobility planning and design, as well as simulation tools that exist and are used in different countries to model traffic changes that affect movement patterns and mobility across the city. Among these studies, Jnr [10] developed a model for decentralized on-demand “electric carpooling” grounded in the community of practice theory to improve sustainable shared mobility. The study aimed to support collaboration between passengers and drivers without relying on a trusted third party. Robertson [31] researched on how to implement e-participation related to mobility policies in Bogotá. The study also identified key dimensions on how new technological forms of participation and communication are assimilated into existing societal dynamics. Aguilar et al. [32] developed a game-oriented approach to improve involvement in urban planning within a smart city. The developed city simulator game was used to promote e-participation and employed as an online-decision-making tool for urban planning by analyzing evolving citizen and urban patterns based on municipal spatial distribution. Anthony Jnr [33] designed a decentralized prototype architecture for a peer-to-peer electric car sharing solution. The suggested approach aimed to provide trustworthiness and cost transparency for sustainable road transportation.

A recent study by Anthony Jnr [34] proposed a green urban mobility policy to enhance green public transportation within the local environment based on a Norwegian viewpoint. The author focused on analyzing current public transportation policies based on a sociotechnical approach by identifying how local communities can improve green urban mobility. Alcaide Muñoz and Rodríguez Bolívar [35] presented various levels of sustainable and smart city structures employing e-participation tools for Central Asian and European countries. The study further reviewed existing e-participation apps or platforms and also examined existing smart city design differences between developing and developed countries. Lopez Baeza et al. [36] presented the modeling of pedestrian flows based on simulations of human movement to support spatial use distributions for urban developments. The study focused on the locality of urban amenities as key constituents of human flow estimates for the design of urban spaces to promote social life for city neighborhoods.

Another study by Ciclitira [37] developed an electric scooter sharing platform in the COUP mobility project operating across Berlin, Madrid, and Paris to support the future of urban mobility without requiring citizens to own a private car. The COUP mobility project aimed to lead the way in redeploying sustainable urban transportation by offering solution reporting, community-based battery swapping, and operations tooling. Anthony Jr [38] developed a novel business model using a data-enabled digital ecosystem to support cities in attaining sustainable shared electric mobility services. The study provides recommendations on strategies and designs for Electric Vehicle (EV) sharing for citizens’ participation in sharing EV assets, strategically highlighting the benefits of shared electric mobility in cities. Furthermore, Stelzle and Noennig [39] proposed an approach for the evaluation of public involvement within metropolitan development. The study provided extensive research on existing tools and approaches available for public involvement for urban development. Anthony Jnr [40] developed a model to promote green mobility governance within smart cities for urban strategy development. Related key performance indicators were proposed in the study to support policymakers to achieve more sustainable, inclusive, and accessible mobility in smart cities. Stelzle et al. [41] provided a co-design and co-decision approach to improve decision-making across collaborative design platforms. The authors further presented the key challenges faced in urban design decisions, presented the findings based on a participatory approach, and also proposed a decision-making approach appropriate for transformation into digital tools.

Additionally, Cooper and Balakrishnan [42] investigated citizen science based on e-participation perspective for urban planning. The study reviewed urban development models and discussed how digital participation can address some of the setbacks faced in conventional planning. Tang and Waters [43] explored how the internet, public participation, and Geographic Information Systems (GIS) can foster transportation planning processes. Findings from the study included the current application of online-based GIS tools, a model of societal participation, and the possible key issues of web-based GIS for societal participation. Berweger et al. [44] contributed to the car sharing project as part of their report, and on assessment and evaluation, the authors discussed how to scale up the mature uptake and use of the insufficiently employed leading-edge technologies as well as the novel deployment and business models of car sharing. Prior approaches for urban mobility planning and design reviewed in this section inadequately examined the strategies, associated elements, and internal and external factors that may impact sustainable mobility planning and design. Therefore, there is a need for research that investigates how sustainable mobility planning and design can be attained based on factors, policies, and strategies related to smart urban development in metropolitan areas.

3. Methodology

This article provides a thorough outline of prior studies on sustainable mobility planning and design in the form of a Systematic Literature Review (SLR). An SLR is a review of prior literature conducted in a methodical way [45]. An SLR is adopted in this approach to ensure that this research is comprehensive and that all significant research published within the field is included. In this study, an SLR is employed as a suitable research methodology and is chosen over empirical techniques like bibliometric analysis since it helps researchers to develop a theoretical approach more effectively than other practical approaches such as expert interviews or workshops, as the SLR provides a synthesis of accessible evidence to address research questions. Also, it helps to improve the foundation of knowledge for current mobility practice and strategies that impact sustainable mobility planning while adhering to the concepts of bias reduction and transparency. Thus, SLRs also offer a medium for the convergence of practitioner and academic knowledge on topics of crucial importance such as sustainable mobility planning and design, which is not well captured with other research methods such as bibliometric analysis, interviews, or surveys. Given the latest commitment by many nations to decarbonize the transportation sector, this SLR is timely. Similar to previous studies [46,47], this SLR was performed based on the protocol defined by Kitchenham [45]. The suggestion depicted by Weidt and Silva [48] specified additional procedures for conducting SLRs and was also utilized. The SLR protocol employed in this study is shown in Figure 1.

Accordingly, each part of the workflow shown in Figure 1 is described below.

3.1. Data Sources and Search Strategy

The research questions to be explored in this SLR are presented in the introduction section of this paper. A survey of all important online databases or libraries is necessary in a SLR. Therefore, the databases Google Scholar, Scopus, and Web of Science were chosen, as these are the most widely employed online libraries for social science research. In order to confirm that all appropriate sources were accessed, a pre-well-defined search string was input into each of the three databases. The search was first carried out in March 2023 and then in 2025. The search string comprises distinct terms joined with the Boolean operator “AND”. Each term focuses on sustainable mobility planning and design based on the research questions being explored. Also, relevant terms were combined in each search string using the Boolean operator “OR”. The search process was translated into search strings for the searches as follows: “sustainable mobility” or “green mobility” or “sustainable mobility planning” or “sustainable mobility design” or “smart urban development” and “smart city development*”and “metropolitan areas*”, and “municipalities” or “sustainable” and “smart transportation*” and “sustainable transportation*” and “policies*” or “initiatives” and “factors*” and “practice*” or “model” and “framework*”.

3.2. Selection of Sources

In this phase, the examined sources were checked to exclude potential duplicates and sources that were not related to sustainable mobility planning and design, such as publications focusing on general mobility, general transportation other than public transportation, etc. The selection process is displayed in Figure 2.

As shown in Figure 2, a total of 236 sources were retrieved from the Google Scholar, Scopus, and Web of Science digital databases. Then, an additional check was carried out on the total 236 sources, and 89 sources were removed due to duplicates, leading to 147 sources. Then, 51 sources were removed based on the title not being fully associated with sustainable mobility planning and design, smart urban development, and metropolitan areas, resulting in 96 sources. Next, 15 sources were deleted due to the abstract not being well aligned to sustainable mobility planning and design methods. Additionally, nine sources were deleted because the subject of the sources was not well linked to addressing challenges related to sustainable mobility planning and design. Then, 72 sources well aligned to the research domain and a further 13 sources (related to prior sustainable mobility planning and design studies, smart urban development, metropolitan area, architecture layers, and SLR) were included through snowballing and to improve the data set, resulting in 85 sources. Lastly, within the final review process for this paper, 18 sources were included to improve the data set, and 3 sources discussing the “case scenario method” were added, resulting in a total of 106 sources. To avoid biases in the selection process, all sources employed were finally checked in order to achieve an optimal selection of sources.

3.3. Inclusion and Exclusion Criteria

For inclusion and exclusion criteria, the SLR employed in this research emphasized sources available in the English language and printed in research journals, conference papers, and book chapters. Gray literature of traditional non-peer-reviewed published materials such as industrial reports and practitioners’ reports was also included, as the topic involves urban policy development. Also, this study opted to include dissertation and technical reports, as many reports from renowned associations such as the European Commission in the EU have published technical reports on the research domain of sustainable transportation. Sources that employed a scientific method (e.g., qualitative, quantitative, experimental, modeling, and literature review) to examine sustainable mobility planning and design were included. Also, publication types such as case reports, opinion/viewpoint/perspective papers, original/research papers, and review papers were included.

Moreover, only sources published from 2000 till date (2025) were considered in this article, this is because publications on real smart sustainable cities started to be published in the year 2000 after the first smart city which was referred to as "a virtual digital city" in the year 1994. Research on smart cities then evolved in the mid-2000s when Cisco and IBM launched separate smart city initiatives. The sources selected also provide appropriate data to provide answers to the research questions stated in this study. Articles that provide data on approaches related to sustainable mobility planning and design were screened, and if the source was grounded in a scientific method, it was included. Studies published in languages other than English were eliminated. As such, this can create language bias, as using only studies published in the English language could limit the comprehensiveness of the literature review and the generalizability of the findings. But English language was selected because most studies related to sustainable mobility planning and design are published in the English language.

3.4. Data Extraction, Syntheses, and Analysis

While SLRs are valuable for synthesizing existing research, this research method is limited to analyzing and summarizing findings from previously conducted studies. It is prominent to acknowledge that the findings are mainly based on secondary data and interpretations of other researchers’ prior work, rather than primary data collected specifically for this study. Additionally, qualitative data was synthesized and extracted from the selected sources. Next, descriptive data analysis was carried out to present findings related to the research questions.

4. Findings

This section offers more detailed answers to the research questions specified in the introduction section of this study. As such, this study does not provide in-depth descriptive and/or bibliometric analysis similar to a prior study [38]. Instead, this study proceeds to examine research questions analogous to prior research [7,14,47,49]. Also, this section presents the action plan as a method that includes key strategies required to assess and promote sustainable mobility planning and design in metropolitan areas for smart urban development.

4.1. From Traditional Mobility to Significance of Sustainable Mobility

This section provides an understanding of the significance of sustainable mobility for urban mobility development. Traditionally, society depends on effective transportation systems, but at the same time, cities are negatively impacted by the same transportation due to CO₂ emissions, air pollution, noise pollution, traffic congestion, and limited public spaces [18,50,51]. The transportation sector is inextricably connected to the climate change issue, and example findings from the European Economic Area (EEA) [52] stated that the transportation sector is responsible for 21% of GHG and about 56% of Nitric Oxide (Nox) emissions within the EU. Similarly, a European Commission [50] white paper titled “Roadmap to a Single European Transport Area-Towards a competitive and resource-efficient transport system” suggests that by 2050, GHG emissions from transportation sector should be at minimum 60 percent lower than those in 1990 and change progressively near zero. These facts have implications for inhabitants’ health, since these emissions from transportation are liable for 70% of other dangerous and harmful substances [4,53]. Hence, the decrease in greenhouse gas emissions from the transportation sector is thus crucial to regional, national, and global efforts to reduce climate change [54,55]. Transportation is linked to issues that impact urban development, including public health, noise and air pollution, etc. [50]. Mobility refers to users’ need, tendency, and/or ability to move, resulting in transportation demand. Mobility also highlights concepts such as multimodality (practice of simultaneously considering all transportation modes in a harmonizing way) and intermodality (practice of connecting various transportation modes for successive use along the same journey or trip) [56].

The role of transportation in sustainable development was first acknowledged at the 1992 United Nations Earth Summit and further emphasized in the Agenda 21 [57]. Similarly, in 1992, sustainable mobility was discussed in the European Commission green paper “Impact of Transport on the Environment” [1,58], which highlighted that while transport had brought several benefits to the economy, it also had social costs (from traffic congestion and accidents) [49]. Intrinsically sustainable mobility concepts can be employed to help address many of these persistent problems in municipalities to lessen the negative impact of transportation [18,59]. The actualization of green mobility is a contributing determinant for sustainable urban development. Sustainable mobility mainly comprises the economic, social, and environmental dimensions of sustainability. From the social dimension, sustainable mobility emphasizes livability and the health of humans, guaranteeing inclusive, safe, and secure mobility for all groups in society [46]. The economic viewpoint aims to decrease traffic congestion, providing affordable, flexible transport fares and lower maintenance costs for transportation infrastructure. It further lowers mobility barriers and reduces traffic accident risks, decreases losses of land and time, and most of all, creates green jobs and economic gains for society, businesses, and municipalities [46]. Additionally, from the environmental viewpoint, sustainable mobility lowers noise, urban sprawl, and smog in cities. It also counters the depletion of natural resources, particularly countering water, air, and habitat pollution and supporting natural ecosystems [60]. However, research on how to reduce the environmental effects of GHGs on transportation is not well investigated.

As compared to traditional mobility, the goals of sustainable mobility in metropolitan areas aim towards hazard reduction, travel reduction, modal shift, and accessibility (as inspired by [19]), as seen in Figure 3. To promote a mobility transition towards a more environmentally friendly means of transportation and effectively decrease GHG emissions, traffic congestion, and pollution, there is a need to achieve more interconnected public transportation in cities [12]. Sustainability in the transportation sector is a much-debated topic, especially in metropolitan areas, where the adverse impacts of emission and noise affect quality of life, health, and safety [5,56]. The European Council [50] adapts the definition provided by the Centre for Sustainable Transportation of Canada, highlighting that a green mobility system is one that supports the main access and development requirements of individuals, businesses, and society, is safely achieved in a way consistent with the ecosystem and human health, and fosters equity between and within successive generations. According to Anthony Jnr et al. [61], sustainable mobility provides access to people, services, goods, and places in an economically viable, environmentally responsible, and socially appropriate manner.

Sustainable Mobility Services in Metropolitan Areas

Sustainable mobility services in metropolitan areas typically comprise fixed-route and micro-transit transportation. Fixed-route services include traditional public transportation that enables ridesharing for passengers (e.g., trains and buses). Micro-transit involves personal care use, first- and last-mile, or point-to-point mobility (e.g., electric bikes, electric bicycles, e-scooters, and electric car sharing schemes) [6]. Thus, sustainable mobility should be affordable, operates fairly and efficiently, and provide multimodal and intermodal alternatives for transport to promotes a viable economy as well as balanced urban development [19,62]. Overall, sustainable mobility mostly reduces waste and emissions, using renewable resources while reducing the impact on the usage of land and the production of noise [63]. Achieving sustainable mobility is considered a wicked problem, as it is perceived as complex or impossible to address since there are several factors involved that often have conflicting preferences. Finding the right solution to address sustainable mobility requires knowledge that is contextualized and understood by all actors involved to achieve stakeholders’ participation or engagement [49].

Additionally, different solutions are being established, such as replacing traditional vehicles with electric vehicles to decrease noise and lower local emissions [8]. Also, the adoption of shared on-demand electric vehicles could make public transportation cheaper, safer, and more flexible while minimizing the number of cars required, keeping up space in metropolitan area [5]. Policy measures related to transportation can help to decrease personal car usage throughout cities. These policy measures can vary from reducing the speed of urban traffic to reallocating urban space to public transportation, making it easier for citizens to access public transport through road pricing and parking controls [3,64]. There are various examples of municipalities providing incentives to change the mobility behavior of citizens. Findings from the literature [23,61,65,66] mentioned that the most employed incentives were providing special parking for carpools, economic incentives for citizens who use public transportation, providing extra compensation to citizens who travel via sustainable transport modes, and also offering facilities (such as bicycle racks or free charging stations for users of electric vehicles). Therefore, there is a need to explore the process of making mobility in cities more sustainable by investigating the current practice of smart urban mobility development and further presenting strategies relevant to managing sustainable mobility.

4.2. State of the Art in Smart Urban Mobility Development

This section provides a discussion on the significance of smart mobility for urban mobility development. By 2050, more than 60 percent of the world’s inhabitants will be residing in municipalities [67]. Intrinsically, smart mobility approaches in metropolitan areas have become important in transportation as well as energy and climate policies [68]. Sustainable mobility entails significant changes in the way transportation is offered, such as decrease in travel demand and reduced use of private motorized modes, a shift to renewable energy, and technological changes for improved energy efficient transportation. Smart urban mobility is a concept that enables cities to achieve sustainable mobility by considering technological, economic, societal, and environmental challenges [68]. The transportation sector, including passenger vehicles and trucks, in 2017 contributed about 86.2% of GHG emissions. This figure is expected to increase in the future due to the growing mobility needs and increasing use of private vehicles in metropolitan areas [69].

Smart mobility is linked to technological developments in transportation, which introduce innovative and new solutions in metropolitan areas so as to lessen the environmental and carbon footprints of society’s mobility, thereby offering new directions for future urban transportation [69]. Smart mobility is grounded in the idea of employing digital technologies in the design, development, and provision of different transportation modes. It fosters more efficient, sustainable, and low-carbon transportation [69]. Smart mobility provides commuters with better alternatives through personalized multimodal travel management and planning via a digital platform. These digital technologies can be embedded in all parts of the transport system, including electrified vehicles, electric charging infrastructure, and provision of renewable energy resources to foster a modal shift [49]. Municipality administrations expect smart mobility platforms to decrease the use and possession of personal vehicles to improve the efficiency of land use, movement of people, and logistics effectiveness by lessening traffic congestion, as well as improving air quality by decreasing exhaust gas [70,71].

Smart mobility relates to both micro and macro levels as related to private and public modes. Smart mobility initiatives at the macro level relate to the supply of an extensive and well-connected network of public transportation modes, which is facilitated by smart management systems such as smart timetables and ticketing, as well as multimodal and intermodal integration. The macro level also includes automated vehicles, carpooling, and car sharing schemes of EVs [8,69]. Micro-level mobility solutions involve the emerging public transportation options used as first and/or last miles to promote a sustainable mobility agenda in cities. Micro-mobilities comprise electric scooters, electric bicycles, and electric micro-mobility devices that are used to support the mobility of senior citizens through self-driven mobility-assisted devices [69]. Smart micro-mobility modes can help improve the conditions of inadequate mobility at a local level. Furthermore, there are limited studies based on smart mobility approaches that are user-centered and market-driven and effectively improve accessible public transportation [71]. Similarly, it is required to examine internal and external factors that impact smart mobility planning and design, which are also aligned with lessening traffic congestion and spatial use, increasing profitability, and reducing the utilization of private cars in metropolitan areas.

4.3. Sustainable Mobility Planning and Design Practices and Key Factors

This section of the article aims to identify the current mobility planning and design practices employed by municipalities and further present the internal and external factors that may impact sustainable mobility planning and design within a metropolitan area. Over the years, vehicles have become more effective; nevertheless, motorized transportation still causes harmful environmental impacts, increased traffic congestion, noise, and air pollution, as well as resource and land consumption [72,73]. Accordingly, the increased dependence on private vehicles and the subsequent road traffic congestion becomes an issue for cities due to the negative effect on citizens’ quality of life [16,72]. Thus, municipalities around the world are targeted in achieving sustainable development, specifically in terms of sustainable mobility planning and design. Transportation congestion is one of the primary issues faced by cities today, and it is anticipated to become worse in the future [23]. To attain a decrease in traffic congestion within and across cities, it is necessary to engage stakeholders during the process of specifying objectives, setting goals, and developing sustainable mobility planning and design initiatives [33].

Sustainable mobility planning and design include a set of sustainable transport strategies aimed at reducing the impact of the trips made by citizens [4,74]. Sustainable mobility planning and design encompass improving the usage of all the existing modes of transport and establishing “co-modality” across the different modalities (bus, taxi train, tram, metro, etc.) and the different forms of individual transport (bicycle, walking, motorcycle, car, etc.). They also include attaining a common objective in terms of environmental protection, economic gain, and managing transportation demand to improve the quality of life of society [63]. Sustainable mobility planning and design are needed to meet the transportation needs of residents and corporations in municipalities and their environments for an improved quality of life. It is grounded in existing urban planning and development practices [7]. Sustainable mobility planning and design processes start by recognizing the knowledge of the current state of the transportation system mechanism while acknowledging existing constraints [75]. This helps to consider the impacts that new solutions could have on the environmental, economic, social, and territorial ecosystem [75].

The main idea for sustainable mobility planning and design is to establish a sustainable transport system within the metropolitan area by improving the transport safety of passengers, improving the attractiveness and quality of public space as related to transport demand, limiting adverse effects on the environment, improving the availability of transport services for all residents, and improving the effectiveness and efficiency of transportation of goods and passengers [16]. According to the literature, sustainable mobility planning and design provide a strategy for cities to decrease their transportation impacts and to influence residents’ travel by offering strategies that promote alternative mobility modes to induce modal shifts [23]. Sustainable mobility planning and design aim to achieve a balance in terms of the city’s “reality”—what is existing already—and “desirability”—what the city intends to achieve—along with the role of transportation in achieving smart urban development goals [3,46].

Sustainable mobility planning and design are important components, as they allow for a greater adoption of public transportation [76,77]. These efforts involve measures that lessen the need to travel, encouraging modal shifts to decrease the length of trips and to encourage significant effectiveness in current transport systems [3]. They aim to promote multimodal and intermodal means of transportation, which entails the use of diverse sustainable modes of transport efficiently integrated to ensure a seamless trip, reducing traffic and freeing up public spaces formerly occupied by cars [12]. Sustainable mobility planning and design involve all modes and types of transportation in the metropolitan area, such as freight transport, private/public transportation, passenger transit, and non-motorized and motorized transportation [16]. Aiming to make all means of transport more sustainable, in December 2020, the European Commission launched its Sustainable and Smart Mobility Strategy to improve the health of the population (as pollution from transportation is one of the main causes of untimely deaths and illness in Europe and is responsible for almost 400,000 premature deaths annually) [78].

According to prior studies by d’Orey and Ferreira [78]; Zavada et al. [74]; Wołek [16]; and Russo et al. [75], sustainable mobility planning and design should comprise “internal factors”, which are measures which can be evaluated using several Key Performance Indicators (KPIs), as shown in Figure 4. As identified from the literature, Figure 4 suggests that for cities to achieve more environmentally friendly and efficient mobility, cities need to have an idea of the internal factors that impact energy consumption by vehicles, as well as greenhouse gas and pollutant emissions. These are also contingent on the functioning and characteristics of vehicles, the road network, and a number of other external factors such as traffic conditions, weather, etc. Accordingly, Figure 5 summarizes the unmeasurable or non-quantifiable elements, termed as “external factors”, that may impact sustainable mobility planning and design in metropolitan areas, adapted from [7,12,23,78].

Certainly, the European Commission considers sustainable mobility a strategic priority for decreasing air pollutants and greenhouse gas emissions (as seen in Figure 4); this can be achieved not only by enhancing infrastructure for transportation and shifting passenger travel modes to those with lower carbon emissions but also by supporting travelers to plan door-to-door multimodal journeys [12]. Thus, it is important that mobility planning policies and mobility design decisions are visibly positioned to promote seamless multimodal and intermodal journeys by improving the link among different public transportation services towards achieving reliable and interconnected sustainable mobility services that are easily accessible to residents and tourists [12,19]. Furthermore, addressing issues related to sustainable mobility planning and design should be carried out through the development of strategies that integrate technological advances, pricing policies, behavioral changes, and urban planning into existing public transportation [29]. As pointed out by Kehagia [63], the mobility choices adopted by individuals are based on the way they travel, as this affects their economic well-being, as well as future urban development.

4.4. Action Plan to Promote Sustainable Mobility Planning and Design

In this section, the strategies and associated elements that impact sustainable mobility planning and design for smart urban development are discussed. With the increase in urban population, there is a need to improve safe access and quality for residents and tourists through sustainable transportation with zero emissions, low noise/pollution for smart urban development [63,79]. As recommended by Ibeas et al. [80], it is also important to identify which locations are the starting points (first mile), for residents, and what means of soft mobility are, used such as walking or cycling. This can help to specify where pedestrian walking paths, bike lanes, bicycle parking places/docking stations, charging stations, etc. can be installed for bicycle users who also use public transportation by car to reach the city (last mile). Bike lanes should be constructed for high-speed use exclusively for bicycles, with well-surfaced, delimited lanes, differentiated with a bright color [80]. This promotes a “park-and-ride” model for users who park their bicycle or personal car and use the bus or train. The “park-and-ride” strategy is required to be coordinated and connected with public transportation systems currently operating within the city. “Park-and-ride” systems are mostly suitable for commuters using personal cars from suburbs or nearby towns that are further away from major public transportation connections [81].

Urban commuters can park their cars and reach their final destination (e.g., the city center) by using public transportation such as electric buses, avoiding increasing congestion and also reducing air and noise pollution in the central areas of the city [12,82]. As park-and-ride interchanges require parking lots, which are mostly located in the city outskirts, there is need for municipalities to provide makeshift or dedicated parking to promote the shifting from private cars to public transportation or uptake of shared mobility to encourage “park-and-ride” systems within and across cities [12,83]. Plausible recommendations such as those from Bardal et al. [21] suggest three key strategies that can be adopted for sustainable mobility in metropolitan areas. First, the authors suggested decreasing the impact of motorized vehicles on the environment and the climate by employing technologies that support transitioning to low-emission fuels [84]. The second initiative involves optimizing the transition to more green, sustainable modes of transport through the combination of initiatives that limit car use (e.g., by implementing parking fees and tolls and limiting parking opportunities) and promoting walking, bicycling, car sharing, and the use of public transportation [21,51]. This will in turn require an increase in the frequency of public transportation and investment in transportation infrastructure mostly for bicycling and walking. Finally, there is a need to reduce traveling via mobility management, urban planning, and the use of digital technologies. As such, cities are providing small city cars, shared public bikes available at municipal parking spaces, or free-floating electric cars for short distances [51].

Therefore, in this research, an action plan is proposed to improve sustainable mobility planning and design, which are emerging as municipalities seek to implement strategies that can stimulate and accelerate a transition towards cleaner, greener, and more sustainable transportation modes. Current action plan strategies such as policies that can be adopted to promote sustainable mobility planning and design in metropolitan areas, as recommended in the literature [19,20,21,51,80,85], are conceptualized in Figure 6. To improve the planning and operations needed for sustainable mobility in urban areas, strategies related to hard and soft infrastructure, pricing and regulation, information availability, and the use of public spaces (transport demand) and associated elements need to be considered, as seen in Figure 6. For instance, road capacity reduction promotes the use of shared mobility assets (EV sharing), which in turn reduces the number of cars on the road. These strategies can be customized for cities of different sizes and economic structures based on the mobility needs of their citizens by the municipal administration’s current sustainability mobility planning for smart urban development. This is because there is no single one-size-fits-all solution with universal applicability towards the actualization of sustainable mobility. This is because the urban environment may be challenged by different mobility difficulties, and different solutions may be deployed for citizens and policymakers. Also, the action plan identifies a set of strategies as a framework that serves as a reference in sustainable mobility planning and design processes by defining a policy and considering the major options for smart urban advancement, as suggested in the literature [4].

Figure 6 depicts an action plan for sustainable mobility strategies employed to achieve sustainable mobility planning and design in metropolitan areas.

4.4.1. Recommendations of Strategies for Sustainable Mobility Planning and Design

This section provides strategies derived from the literature and best practices from different cities that have been implemented for sustainable mobility planning and design. Findings from the literature [4,63] reveal that the strategies range from the use of High-Occupancy Vehicle (HOV) lanes to reducing the use of private cars in city centers and historical and/or central places, creating of one-way streets, installing urban toll systems, and introducing expensive taxes for parking in dominant locations within the city. Another action involves measures to improve soft mobilities such as cycling and pedestrian network quality [4,63]. Improving pedestrian networks is critical for sustainable mobility planning and design, specifically for short distances, also based on the fact that pedestrians are among the most susceptible road user groups [86]. Another perspective is to provide suitable accessible conditions and to contribute to the economic development of different metropolitan areas. This is because if the costs of traveling between different service, residential, commercial, or industrial areas are low, this will result in an increase in commercial prospects for different economic activities [4].

Moreover, another prominent strategy is the use of electric vehicles that use green energy sources to reduce emissions. Thus, restructuring the pedestrian network and improving required components such as crossings, circulating lanes, multimodal interfaces, and pedestrian green spaces is necessary for smart urban development [62,87]. The design, deployment, and administration of the pedestrian network should consider pedestrian safety, attractiveness, comfort, and effectiveness. The needs of populations with reduced mobility should be considered while amending existing transport infrastructures and thoroughly planning new strategies [88]. Similarly, cycling networks have similar requirements to the pedestrian networks but also require additional effort in the provision of supporting amenities such as devoted lanes, cycling parking, garages, safe crossings, shared spaces, subsidized maintenance cost, and information services [4]. Another set of strategies is associated with the need to enhance the overall effectiveness of intermodal and multimodal transport services, which involves not only operational proficiency but also its energy and environmental effectiveness.

Certainly, the efficacy of public transportation services relates to the optimization of operating environments, predominantly regarding the safety, reliability, and travel speed associated with deployment, operation, and maintenance [4]. The availability of information is another factor that needs to be taken into consideration to inform citizens and other stakeholders in the city about sustainable mobility with regard to smart urban development. Municipal administrations should not assume that citizens will find out about sustainability initiatives being proposed to the community [3,89]. Publicity and advertising are means of mass communication used to publicize information to a wider community [90]. As such, individualized marketing is encouraged via dialog-based methods for promoting the use of public transportation, cycling, and walking as alternatives to personal car use. The public perception and acceptance of sustainable mobility initiatives can be high if the policy measures are presented as a package that can efficiently be implemented [91]. This necessitates building trust and acceptance between involved actors over time, so active involvement and communication are essential [3]. To create information networks and raise public awareness across the local community, both informative events and forums should be organized to discuss with citizens interested in smart urban development [3].

Mobility discussions, forums, and informational events such as seminar-type meetings, and interactive activities (co-creation gathering) can be organized where citizens are invited to learn about proposed sustainable mobility strategies and express their disapproval or approval [66,92]. Therefore, the provision of information ensures effective communication and involvement through the drafting of policy measures and by highlighting the benefits to society [3]. Also, cultural and economic differences of citizens in different countries should also be considered, as more countries in Europe participate in sustainable mobility practices as compared to other emerging economies [10,11]. Moreover, legitimacy must be built on an inclusive and participatory approach that entails “selling the idea” of sustainable mobility to inhabitants, groups, and localities by explaining the need for behavioral changes and convincing all stakeholders of the importance of their participation. As mentioned by Banister [3], in most cases, there are strong positive measures (healthy transportation, reduced global warming, and cost effectiveness) that need to be promoted to increase users’ commitment to sustainable mobility.

4.4.2. Technological Requirements for Smart Mobility

Findings from Torrisi et al. [85] suggested the following technological requirements for the functioning of an intelligent transport system that can be employed to foster smart urban mobility development, as seen in Figure 7.

As seen in Figure 7, the technological requirements should include traffic radar sensors, cameras, etc., which measure traffic flows in real time, providing Variable-Message Signs (VMSs) to individuals communicated using GPRS wireless networks to relay real-time data to monitors and manage installed traffic sensors and devices. These VMSs are mostly digital road signs employed to inform road users about real-time traffic conditions and specific temporary events [85]. VMSs are often connected to a operated control center through a radio link or a local network. Data is collected from floating vehicle data and inductive loops used to categorize vehicle types moving across the city. Furthermore, discussions on the role of AI (Artificial Intelligence), IoT (Internet of Things), and big data for predictive analytics in mobility planning, as well discussions on the data privacy concerns associated with real-time mobility tracking and interoperability between different transport networks are already presented in the literature [93,94,95] and, as such, are not covered in this study.

Moreover, there is need for a platform that uses traffic data, historical data, real-time data, and open data [9,62] to perform traffic forecasting, prediction, and estimation regarding the present and potential traffic conditions in case of the occurrence of irregular events based on traffic measures and events. These platforms should support a dynamic, multimodal, and intermodal search path to enable users to specify the shortest path of transportation considering commuting costs and time linked to the real-time conditions or a simulated scenario of actual/current and future conditions of the entire transport network. Also, the input data can be used to generate simulations to optimize transport network operation, provide infomobility to vehicles and drivers on traffic conditions, and provide support for decision-making in smart urban development planning and management procedures [85].

4.4.3. Case Scenario of Smart Mobility Planning and Design

This study further employed a case scenario as a qualitative method to present findings. The case scenario method is a technique employed in addressing uncertain and complex societal issues such as those involving smart cities [94]. It involves establishing theoretical situations that provide the grounds to explore different practical solutions for solving problems and making decisions [96]. Case scenarios are typically carried out via focus group or domain expert discussions and allow researchers to examine the current situation, opportunities, challenges, and recommendations [94]. Case scenarios provide a medium for practical rational decision-making, allowing for the application of knowledge to solve real-life situations [97]. A case scenario of the technological advancements and innovations for smart mobility planning and design implemented in Norway as part of the smart and sustainable city project (https://cityxchange.eu/ accessed on 3 August 2025) is shown in Figure 8. The case scenario is based on the implementation of a smart mobility strategy based on an electric mobility solution that uses the Distributed Ledger Technology (DLT) IOTA Tangle (https://blog.iota.org/iota-cityxchange-community-update-85f43894bcca/ accessed on 3 August 2025).

Furthermore, qualitative data was also collected from two companies that provide sustainable mobility planning and design services regarding the technological requirements and conditions for DLT-driven electric mobility as a service solution [98]. The collected data is presented in the ArchiMate modeling language (archimatetool.com) to show an overview of the technological advancements and innovations in the field. The ArchiMate modeling language was utilized in this research as a smart tool that can be designed to meet different actors’ requirements. However, the ArchiMate language does not facilitate automated reasoning; it offers concepts, objects, and interactions that are applicable mainly for modeling enterprise digitalization. ArchiMate is particularly suited for modeling current and future enterprise operations, as it provides concepts for designing a real-life business and societal model that fits businesses, infrastructures, applications, and technologies. Thus, based on the data collected, sustainable electric mobility is modeled, as seen in Figure 8.

The developed solution is presented as a “proof of concept” that supports residents in reserving and making payments for a multimodal journey provided by several transport providers seamlessly in one step. Similar to Figure 7, mobility data is collected from different sources, as seen in Figure 8, and then the mobility data is processed and analyzed, and finally, this mobility data is visualized for the end users other stakeholders to support the operation of smart mobility planning and design. In this study, the use case of modeling for smart mobility planning, design, and system operation in ArchiMate is presented as a proof of concept that proves that the model is technically and financially feasible and that citizens will use the services to the desired extent. Similar examples of the model were already successfully implemented in the smart city +cityxchange project, where such models were employed to model shared mobility services, energy exchange. and innovative models for community exchange, serving as a reference architecture.

Thus, the novelty and scientific value added by the model developed in this study is attributed to the fact that the approach offers a framework for smart mobility planning, design, and system operation that can be applied across different cities. Additionally, Figure 8 presents the physical infrastructure, technology, data space, application and data processing, business, service, and context layers. The elements in each layer are discussed in

Table 1. Description of the “smart mobility planning, design, and system operation”.

No	Layer	Elements	Description
1	Physical infrastructure	Public transportation	As seen in Figure 8, public transportation comprises ferries, car sharing, flights, buses, taxis, city bikes, etc., which provide mobility services to citizens/tourists.
2	Technologies	Data integrity infrastructure Dedicated cloud service (powered by Firebase) Micropayment infrastructure (Distributed Ledger Technology (DLT))	Real-time data is transmitted from public transport to the DLT micropayment infrastructure. This occurs when users of these public transportation modes scan using a Quick Response (QR) code/Near-Field Communication (NFC) tag or use the start button. The data is transmitted via a dedicated Masked Authenticated Messaging (MAM) channel. MAM is a second-layer data communication protocol that offers functionality to emit and access an encrypted data stream over the deployed DLT. The data integrity infrastructure adds integrity and privacy to data streams using MAM. The micropayment infrastructure allows for micropayments for each trip from each city traveler/citizen to the transport aggregator and Transport Providers (TPs) via an API. Next, the dedicated cloud service transmits the collected MAM channel details to be stored. Additionally, the data integrity infrastructure allows for the reservation and recording of travel on the DLT. It provides an audit trail to guarantee the integrity of payments distributed to TPs within the city via an API.
3	Data space	Total Traffic Control (TTC) storage DLT storage Cloud-based service (Firebase)	The Total Traffic Control (TTC) storage stores all the electric mobility-related data that is used by the TTC application. The DLT captures the location data and encrypts and publishes data on the citizens’ journeys to be used by the DLT backend. The DLT also sends and receives data from the TTC application. The cloud backend service connects to Firebase, which stores MAM channel details. It also sends stored data to the DLT.
4	Application and data processing	Electric mobility app TTC application (backend processing) Digital asset payment system (eDigital Wallet status) Registered dedicated payment system terminal DLT backend	The electric mobility app is used by the citizens to reserve electric mobility services and is connected to the TTC backend application. The TTC application provides backend processing of data to the electric mobility app. It also connects to the DLT. Then, the digital asset payment system provides the IOTA Wallet Status for the electric mobility app. to support city traveler/citizen payment. The eDigital Wallet is also connected to the registered dedicated payment system terminal, which processes micropayments. It also provides data for electric mobility services via APIs. The registered dedicated payment system provides a terminal that processes payments made from the traveler/citizen to the respective TP. The DLT backend processes electric mobility services from the DLT. It is also connected to the digital asset payment system. It processes location logging and hash location storage for the traveler/citizen via APIs, as seen in Figure 8.
5	Business	Infrastructure company City traveler/citizen DLT company Transport Provider (TP) Aggregator service providers	This layer comprises the stakeholders that collaborate to provide electric mobility services. Also, in this case, this layer involves the transport providers, which are the transport companies that provide mobility services to city travelers/citizens. Lastly, the aggregator service providers ensure that the TPs receive payment for the journey made by the city traveler/citizen.
6	Service	Multimodal journey Billing service (send and receive payments) City traveler/citizen functionalities Transport provider functionalities	All services provided by the digital asset payment system to support electric mobility services are captured in this layer, as seen in Figure 8. These services are provided to the city traveler/citizen and TP.
7	Context	Green transport means Seamless eMobility as a service Increase adoption of eMobility solution Sustainable or green public transportation	This involves the main requirements that are aligned with sustainable mobility planning and design.

. The details of each layer have already been discussed in the literature [98]. Additionally, similar layers were discussed by Anthony Jnr et al. [62], who presented an interoperable architecture to improve electric mobility adoption in smart cities, and Bokolo [95], who explored sustainable mobility sharing based on a mixed approach.

As seen in Figure 8, Application Programming Interfaces (APIs) are deployed, offering diverse smart mobility-related services. Each of these implemented APIs is described in

Table 2. Specification of APIs for smart mobility planning, design, and system operation.

API #	API Name	API Consumer	API Description
1	TPRegister	Transport provider	Helps the “TP” perform company registration.
2	TPLogin	Transport provider	Helps the “TP” log in and manage their account.
3	TPsGet	Transport provider	Provides the TP with a list of all transport types available within the metropolitan area.
4	TPTariffCreate	Transport provider	Helps to create and set tariffs for the different transport types.
5	TPTariffGet	Transport provider	Retrieves and shows tariffs for available transport types.
6	TPPayment Update	Transport provider	Responsible for setting the receiving web address for DLT/digital tokens.
7	TPUserRegister	City traveler/citizen	Helps end users such as citizens and tourists to complete registration.
8	TPUserLogin	City traveler/citizen	Helps the end users to log in to their stipulated account.
9	UserJourneyCreate	City traveler/citizen	Supports end users in the reservation of a multimodal journey.
10	UserJourneysGet	City traveler/citizen	Facilitates the retrieval and display of reserved and past multimodal journeys.
11	UserJourneyEventCreate	City traveler/citizen	This API helps the end users to perform the following: Plan an electric-based multimodal journey. See a list of public transportation means. Locate public transportation means to start each journey leg. Record the beginning and end of the journey leg.
12	UserPaymentMethodCreate	City traveler/citizen	This API helps the user to perform the following: Set up and fund the DLT/digital wallet. Pay for travel/journey. Log booked journeys with the DLT. Log payments made to the DLT. Separate user payment and send correct amounts to the TPs.
13	UserPaymentMethodGet	City traveler/citizen	Retrieves and displays payment gateway availability to the user.
14	UserPaymentMethodUpdate	City traveler/citizen	This API updates payment information and also returns proper fees from the correct TP when booking is cancelled.
15	UserPaymentMethodDelete	City traveler/citizen	Deletes payment information from the electric mobility user profile.
16	UserPaymentMethodFundsAvailable	City traveler/citizen	Displays payment method fund availability data/information to the user.
17	Hash Location Storage	City traveler/citizenTransport providerTransport aggregator	Allows for the booking and recording of travel through the DLT and provides providence to ensure the reliability of payment allocation to TPs. Stores hashes of the recorded locations using MAM. Recovers location hashes to the transport aggregator and TP to process refunds for cancelled trips.
18	Process Micropayments	City traveler/citizenTransport providerTransport aggregator	Confirms that registered data is personal and only accessible for secured users with MAM access within the DLT. Also, supports the processing of micropayments for each user trip to the transport aggregator and TP.

and represents application and data processing and technology layers shown in Figure 8 and Table 1.

5. Discussion and Implications

5.1. Discussion

The goal of sustainable mobility is to safeguard ecosystems, the global climate, and natural environments while also supporting the social and economic pillars of sustainable development for an improved quality of life for residents. Sustainable mobility can be regarded as mobility in harmony with the universal notions of sustainable development [21,99], thus promoting the accessibility of individuals and societies by providing an efficient and affordable choice of transportation [60]. As stated by Ison and Ryley [65] and Tafidis et al. [100], sustainable mobility refers to the ability to meet society’s transportation need to gain access and freely move without negatively affecting other important human or environmental values. Sustainable mobility is included in Sustainable Development Goals (SDGs) Part 11.2 to provide accessible, safe, cheap, and green transport infrastructure, offering road safety specifically through the improvement of public transportation [101]. Sustainable mobility planning and design have become vital tools in order to outline a set of consistent initiatives proposed to address the mobility and accessibility needs of citizens and cities and provide high-quality and greener means of public transportation [4].

Sustainable mobility planning and design are employed to achieve a new culture for the transportation of inhabitants and visitors, considering the minimization of CO₂ emissions and provision of accessible transportation networks, inclusive mobility for all, and common spaces for all citizens [20]. Sustainable mobility policies can help to decrease personal car use through the uptake of cycling and walking and the development and reallocation of space to foster public transportation through road pricing, toll management, and parking controls [63]. Effective realization of sustainable mobility entails the full inclusion of key stakeholders so that they can understand the need for several mobility policy strategies and also support these mobility initiatives. Although sustainable mobility plays an important role in the actualization of smart urban development, it is only viable with the acceptance of the people [3]. Thus, there is an urgent need for municipalities to improve public transportation in their cities and identify strategies that need to be employed in the short and medium terms to improve sustainable mobility [102,103].

The findings of this study present the significance of sustainable mobility services and smart mobility for urban mobility development. The finding is similar to results from a prior study by Holden et al. [49], who suggested that sustainable mobility relates not only to the safeguarding of the natural environment but also the well-being of people, as the condition of the local environment has become a significant factor in transport polices. Thus, sustainable mobility is strongly associated with the local environment’s livability and vitality [2]. Hence, sustainable mobility concerns the promotion of healthy forms of transportation such as walking, cycling, and the use of public transportation [29,104], as well as improving the local air quality, especially for more vulnerable populations in the society (e.g., older people, those with walking difficulties, etc.), by considering the needs of all users in society and supporting an inclusive transport plan [104].

Additionally, the findings from this study provide evidence for the best practices among the current mobility practices employed by municipalities for smart urban development, considering that sustainable mobility design and the external and internal factors that influence sustainable mobility planning and design in metropolitan areas have not been well researched. Analogous to results from the literature [16], sustainable mobility involves the inclusion of the notions of sustainability in mobility planning, design, and policymaking. However, to achieve broader benefits for metropolitan areas, sustainable mobility policies should consider the planning of urban spaces [16], as a good match of mobility planning and design with urban development and land use may foster the use of public transportation, as well as soft mobility options. In metropolitan areas, public transportation systems that are not adequately managed in compactly developed areas may influence citizens not to give up the use of private cars, as efficient travel demand is high [69].

Moreover, the need for more sustainable planning as a means of addressing issues related to smart urban development has been widely recognized [4]. Prior studies have examined sustainable mobility planning in the urban context [12,13,14]. Findings from this study present key strategies and associated elements that impact sustainable mobility planning and design for smart urban development that are not well covered in the literature. Accordingly, this current study proposes a (qualitative) action plan as an approach to assess key strategies needed to promote sustainable mobility planning and design, including internal and external factors that may influence the attainment of sustainable mobility in metropolitan areas. The suggested action plan offers a comprehensive approach with ready-to-use guidelines to streamline the actualization of sustainable mobility planning and design initiatives by decision/policymakers or transportation departments in municipalities. Finally, the findings from this study offer recommendations to fulfill the public transportation needs of cities considering environmental, technological, social, and economic factors. The action plan proposed in this study offers a central strategic tool to promote quality of life and mobility in metropolitan areas.

5.2. Research Implications

Transportation has become indispensable to the daily operation of cities and communities. Yet the dependence on motor-powered transportation for everyday use is a substantial contributor to climate change, air pollution, and urban congestion, which is an issue in metropolitan regions [85]. Lowering energy consumption by vehicles, as well as greenhouse gas and pollutant emissions in travel, is part of a wider move by municipalities towards achieving sustainability in the transportation sector. However, this is a very challenging goal, as it would require the radical decarbonization of the entire transportation sector [28]. As such, over the years, much research has been conducted to improve mobility in metropolitan areas. The sustainable mobility concept is concerned with people traveling via means that are economically viable, socially just, and environmentally responsible and has gained popularity in society, research, and policy [17]. A change in sustainable mobility in metropolitan areas, including the prioritization of non-motor-powered forms of transportation, is thus important to improve smart urban development towards reducing air pollutants, CO₂ emissions, and energy consumption from the transportation sector [55].

But sustainable mobility is faced with several issues such as the need to decrease the use of private vehicles in cities without affecting mobility, accessibility, and sustainable means of traveling within and across cities [62,79,105]. Moreover, several factors influence sustainable mobility in metropolitan areas, such as the characteristics of the vehicle used; accessibility, capacity, frequency of service, travel time, safety, reliability, and availability of designated and dedicated stops for public transport users; connectivity; operator behavior; current road conditions; etc. [79]. Thus, researchers such as Fenton [55] have suggested strategies that can be employed to accelerate sustainable mobility, for example, sustainable mobility business models to promote ridesharing or car sharing services, pioneering schemes to promote cycling, and the availability of public transport such as bus rapid transit, trains, trams, etc.. Also, there are a few studies that aim to provide an approach that supports municipalities to develop effective and efficient sustainable mobility planning and design tailored to the economic, social, environmental, and technological requirements of metropolitan area [106].

To this end, the transformation to sustainable transportation in a metropolitan area requires a model shift in mobility planning and design. Therefore, this study proposes an action plan (as seen in Figure 6), which can be employed as a decision support tool that provides an understanding of the metropolitan area with much unexploited potential for change and helps recognize the definite type of intervention to be employed. The technological model (as seen in Figure 7) is reproducible and adjustable to different geographic locations, without high economic demands or technical experience requirements, bringing together concepts and practices to provide a detailed and extended description of sustainable mobility planning and design. Findings from this study provide integrated sets of strategies necessary to formulate a sustainable vision for municipalities’ public transportation system development, which is not well addressed in the metropolitan area research. Furthermore, this study explores applicable strategies that can be adopted to deploy accessible and environmentally friendly mobility in urban spaces devoted to promoting change towards the transition to a multimodal transport system.

5.3. Practical Implications

Transportation greatly influences quality of life and sustainability in cities. Primarily, metropolitan areas are faced with transport-related noise, air pollution, congestion, occupation of public space by traffic, and mortality and morbidity caused by pollution and mobility-related accidents [22]. Overall, sustainable mobility planning and design aim to construct a healthy environment for residents, provide an economically viable and accessible municipality, and safeguard a secure and safe metropolitan environment ensuring that the mobility needs of its citizens and society at large are met, involving inhabitants and other urban mobility factors to promote key stakeholder participation [22]. These efforts also focus on reducing related emissions from urban transportation to contribute to addressing climate change goals [25].

As such, municipalities are proposing policies to prioritize the adoption of public transportation, cycling, and walking and move towards the zero-emission goal for the decarbonization of the transportation sector to mitigate climate change and global warming [68]. The practical implications of this study include the provision of an action plan as a road map for smart mobility development to act as a recommendation for decision-makers who plan to deploy appropriate measures towards sustainable mobility in metropolitan areas. This study indicates technological requirements (see Figure 7), as well as best practices to promote environmentally and socially inclusive sustainable mobility. Evidence from this study presents the current mobility practices employed by municipalities for smart urban development, the internal and external factors that may influence environmentally friendly mobility planning and design within metropolitan areas, and strategies that impact environmentally friendly mobility planning and design for smart urban development.

More importantly, the findings from this article suggest that sustainable mobility planning and design strategies should comprise effective mobility operations, the development of non-motorized public transport, multimodality/intermodality, road transport safety, and the promotion of environmentally friendly, clean, and green-energy vehicles. Another significant finding is the relevance of technology in sustainable mobility planning and design. This is because technology plays a vital role in the sustainable mobility perspective. Using apps, it is easier to share electric vehicles, find shorter routes, and in turn measure travel distances and times. Technology is also crucial to deploy, control, and promote car sharing and carpooling schemes, which improve citizens’ quality of life and well-being [6]. Additionally, the findings from this study consider the key sustainable mobility planning and design factors that enable an effective modal interchange for smart urban development. In particular, the findings from this study will be of great interest to researchers interested in qualitative methods to analyze, assess, and benchmark current transportation models being adopted.

6. Conclusions

This study aims to explore sustainable mobility planning and design strategies and policies for smart urban development in metropolitan areas by presenting an action plan as an approach to assess key strategies needed to promote environmentally friendly mobility planning and design. Qualitative data was collected from the literature employing an SLR, and descriptive data analysis was conducted. Findings from this research provide a description of existing works on sustainable mobility approaches in cities, which are important for the transition towards low- and zero-emission transportation. The findings from this study identify internal and external factors required to manage sustainable multimodal and intermodal mobility based on a city’s transport policies and actions. More importantly, the findings specify the most efficient actions that should be employed either in the short or long term to achieve multimodal and intermodal transport systems specifically through the development of sustainable public transportation. Also, the technological requirements needed to achieve sustainable mobility planning and design are presented in this study. The proposed action plan and technological model can be employed for sustainable mobility performance assessment to promote multimodal and intermodal mobility. Mobility designers, decision-makers, transport technicians, municipality administrators, etc. can benefit from the approaches proposed in this study to evaluate current transportation initiatives for future mobility planning and design case scenarios in metropolitan areas.

Limitations and Future Works

A few limitations are noted in this study. First, an SLR is employed as the methodology in this study, and although this is a scientifically sound method, it lacks theoretical and operational validation in practice, which should be noted when considering practical implications. Additionally, the action plan (roadmap) presented in Figure 4, Figure 5, Figure 6, Figure 7 and Figure 8 remains on a generic level and must be specified for operational use in metropolitan areas. Moreover, only secondary data was employed in this study to investigate sustainable mobility planning and design. The role of transport models was not assessed within this article, as it was not within the scope of the current study. Future studies will collect primary data to further test the usefulness of the developed approaches employing data collected from interviews and focus group workshops. Future works will contribute to providing a matrix that visualizes and quantifies the external and internal factors based on quantitative data collected from citizens, municipal administrations, and other stakeholders in urban environments. Future studies will also consider exploring transport models that are digital or mathematical representations of real-life mobility systems, employed to analyze and predict the movement of people and goods within the city. Lastly, the action plan presented in this study will be empirically and practically applied in a low-level setting in a municipality to evaluate the applicability of the strategies and elements towards planning and operations of public transport.