From Paratransit to Emerging Transportation and Micro-Mobility: A Conceptual Discussion on Alternative Transportation from a Systematic Literature Review

Abstract

This study outlines a conceptual discussion within the transport planning field through an extensive systematic literature review that draws upon diverse case studies on alternative transportation. The article focuses on context-dependent multidimensional understandings of alternative transport services in the Global South and the Global North, which other systematic literature review studies lack. Thus, this research aims to pose conceptual differentiations between paratransit, informal transportation, emerging transportation, and micro-mobility to pinpoint specific characteristics and varied understandings of such phenomena for further academic research within transport planning. Tendencies of research approaches and case studies’ policy and regulation based on geographical zones are also addressed. The outcomes enrich the field of study at a theoretical and practical level toward its application in policy and regulation for green transitions of alternative transport services.

1. Introduction

The term alternative transportation (AT) refers to transport means that usually are an alternative to the automobile and other conventional vehicles, and whose uses respond to people’s needs in a specific socio-historical, economic, and political context see [1,2]. A criticism of the AT concept is that it potentially reinforces the notion that automobiles are the norm in terms of transportation means and that any other means are alternatives to them. In some research, the concept of AT is used to mean sustainable or active transportation [1,3,4], or it can even be understood as human-scale mobility [5]. Hence, this paper will continue referring to and using the concept of AT, enriching it by considering its sustainability, active mobility, and human-scale characteristics.

This study acknowledges and differentiates different research approaches, conceptual understandings, and contextual case studies for policy and regulation of AT in the Global North and the Global South. In this paper, the Global South and Global North are conceived as geographical zones that go beyond descriptive nation economic-based terms (such as developing and developed countries), where cultural and socio-historical power relationships and inequalities between territories are key for their understanding see [6]. This approach supports the zone-based contextual multidimensional focus of this study. The goal of using such a terminology is to clarify that the current scientific literature on the field of study consistently and systematically remarks how research approaches and policy and regulation are different between zones of the Global South and the Global North. Therefore, this research partly aims to avoid generalizations among the cases of study where their contextual multidimensional aspects are essential elements to consider, although the analyzed academic literature does not actively consider it.

The academic systematic literature review (PRISMA) [7,8] in this article aims to provide a detailed description of study cases on alternative transport services (ATSs) of the world, showing differences and similarities between them in theory and practice. The review is divided into different sections: (1) barriers and opportunities of mobility potentials, (2) access to transport planning and workers’ stigmatization, (3) the internal organization of transport services, and (4) micro-mobility services’ externalities for regulation and policy. In a second step, the conceptual discussion in this study aims to offer conceptual differentiations that attest understandings of different contextual processes of ATSs toward their possible planning, formalization, and sustainability. Additionally, the discussion assembles mediations between technical and (social) behavioral understandings of the phenomena that relate to geographical contexts [9].

As mentioned, in this article, the places where the case studies on AT are taken from are considered as multidimensional [10,11] within transport planning. Here, place denotes a specific context with specific historical characteristics that shape processes, interactions, and the behavior of society [9,12]. Case studies on AT phenomena are geographically far away from one another in a time–space context. For instance, the use of cargo bikes (ladcykler) in Copenhagen could be considered as a paratransit phenomenon, which is vastly different from similar cases in developing countries, due to its socio-historical process of creation, implementation, and development. Theory and methods applied to the cases of Copenhagen’s cargo bikes and, for example, Mexico City’s motorcycle cab service, therefore, must be focused and managed in diverse ways while at the same time considering the scientifically developed studies performed so far. For instance, the case of the kombi-taxis in Johannesburg [13] and the case of the hand-pulled rickshaw in Kolkata [14] are different from each other. In the first case, the city had processes of gentrification related to social class position and people’s skin color, which resulted in the need to create personal and communal transportation for center–suburb commutes. In the second case, the transportation has a long history, since it passed from being used by under-served people to being also used by the middle class, and lately, it has been contributing to the social and cultural assimilation of the city.

The realm of literature on AT also includes studies in which innovation and business are the focus of analysis. Studies on shared mobility systems and mobility as a service (MaaS) highlight collaborative business models [15,16,17,18,19,20], innovation frameworks [16,17,18,19,20,21], sustainability [16,17,18,19], and policy and regulation [15,17,18,19,21]. Moreover, different research studies have also addressed frameworks that support technological and service innovations [21] and promote sustainable practices for micro-mobility services [15,21,22]. Relevant studies of this kind highlights the importance of contextual considerations in transport planning [15,16,17,18,19,20,21,22]. However, in this regard, most of the literature addresses different cases that are only in the Global North.

This research attests that studies on AT tend to be divided into informal and formal within current academic research, depending on the context of the geographical zone. Furthermore, a considerable amount of the academic literature on micro-mobility draws on cases in the Global North and on e-scooter services, whereas numerous academic studies on informal transportation and emerging transportation draw on cases in the Global South and on motorcycle cab services.

Current studies involving systematic literature reviews on ATs (either on informal transportation or micro-mobility) do not address these global phenomena from a multidimensional perspective, which would allow them to acknowledge the conceptual differentiations and tendencies of research approaches based on the geographies of the case studies involved see [1,23,24,25,26,27,28]. Therefore, as a contribution to the transport planning field and research aim, the conceptual differentiations offered in this study aim to help researchers avoid generalizing understandings within AT phenomena in the Global South and the Global North. Moreover, this entails acknowledging the multidimensional contextual place as a methodological consideration in research. Finally, this article’s findings can inspire the creation of further research and policy and regulation for sustainable AT across the world.

2. Systematic Literature Review (PRISMA) on Alternative Transportation

In this section, I address the diverse academic literature on ATSs (paratransit, informal transportation, emerging transportation, and micro-mobility) that I have gathered to understand their different research approaches.

This study’s systematic literature review is based on the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) [29], see Table S1. Although coming from medical science, PRISMA is a thorough academic literature review method that can also be implemented in social sciences and humanities research.

The time period for reviewed academic literature in this study was from the early 2000s to 2025, using Scopus, Google Scholar, and the Royal Danish Library as the main database sources (see Table S1), together with the official webpages of governments and organizations which were used to extract relevant reports. The review process started during my PhD research in 2016 and continued until after its conclusion, with the review for this publication finishing in 2025. Boolean logic clusters, made by hand using keywords related to the field of study, were the main implemented method of information search implemented by the author.

Exclusion of literature was conducted by screening, scanning, and skimming the literature titles, abstracts, and conclusions to remove texts that were unrelated to this study’s scope and aim (see Figure 1). For example, quantitative research on paratransit services’ logistics and probabilistic models was excluded due to incompatibility with the field of study in connection with this study’s aim see [30,31,32,33]. However, the included literature (88 studies) was thoroughly and entirely read (see Figure 1).

The literature review inclusion criteria included topics that stemmed from the revised passenger AT literature as its common denominators, focusing on context-dependent multidimensional understandings. Moreover, the literature on ATs that actively addressed a case study analysis in the Global South or the Global North and implemented a social science or humanities scientific method was chosen for inclusion in the review (see Figure 1). As a result, the chosen literature was grouped into the topics of (1) barriers and opportunities for mobility potential, (2) access to transport planning and worker stigmatization, (3) the internal organization of services, and (4) micro-mobility services’ externalities for regulation and policy, which correspond to the subsequent sections of this literature review.

2.1. Opportunities and Barriers for Improving Alternative Transportation Cases Around the Globe

According to the academic literature, opportunities and barriers for improving worldwide ATSs in the Global South have been presented in diverse ways. Most of those ATSs involve motorcycle cabs (see Table 1). Regarding the barriers, in some cases (such as in Bo-Town, Sierra Leone; Dar es Salaam, Tanzania; Auchi, Nigeria; Southwest Nigeria; Lomé, Togo; Barranquilla, Colombia; Recife, Brazil; Caracas, Venezuela; Zimbabwe; Vietnam; Togo; and other cases in Benin), ATSs lack safety measures for its users and drivers (for example, Vietnam’s motorcycle cab service is involved in 60 percent of the total road accidents and 80 percent of drivers violate the roads laws [34]). Therefore, ATSs are contributing to an increasing number of road accidents in cities, mainly because of drivers’ violations of road regulations. In addition, there is constant competition for passengers between drivers to make more money. This happens due to drivers not having a salary and usually not owning the vehicles with which they work, which increases the risk of accidents and premature vehicle wear. Drivers tend to speed and not care about vehicle maintenance, since they are more concerned with making money by increasing their daily number of trips see [34,35,36,37,38,39,40,41,42,43].

In other cities (such as Auchi, Nigeria; Barranquilla, Colombia; Recife, Brazil; Caracas, Venezuela; and in cities in Vietnam and Sri Lanka), ATSs have variable travel fares and are even sometimes overpriced, meaning that the users and the drivers negotiate. However, prices are usually not based on travel distances. In some cases, such as in South America, the price of the service is higher than formal public transport means. Therefore, non-regulation of informal transportation fares could favor direct or indirect abuse of the users by drivers see [34,35,38,44]. In the cases in Lomé, Togo; Auchi, Nigeria; and Vietnam, ATS workers do not have an established work schedule or coordinate routes, and most of them work an average of 10–12 h every day for 6–7 days per week. Therefore, being an AT driver is considered a street job and drivers are exposed to challenging environment conditions. This causes problems for the drivers’ health, mostly spine and hip pain, usually due to bumpy roads, and headaches due to exposure to the sun see [34,35,37,45].

In other cities (such as in Auchi, Nigeria; Togo; Benin; Dar es Salaam, Tanzania; Bo-Town, Sierra Leone; and cities in Southwest Nigeria and Sri Lanka), most AT drivers do not own the vehicle they use for working. People that own their vehicles are usually only vehicle renters or service organization leaders; in the city of Auchi, drivers tend to quit their jobs if other opportunities come, since only 69.7 percent of the drivers own their vehicle and those who do not own their vehicle tend to earn an exceptionally low income [35]. There are several consequences related to this characteristic: There is a clear misbalance in income earning between the owners of the vehicles and their drivers. That is because drivers usually must pay non-negotiable dues to their organizations and/or a fixed daily payment to vehicle owners through non-formal contracts based on trust (ethnicity-based interactions). In Sri Lanka’s case, the high price of fuel adds to that issue [44]. Hence, this feature favors a systematic process of inequality between service workers, vehicle owners, and organization leaders. In some cases, such as in Bo-Town, a driver’s income is not enough to sustain a family after paying bills. In most cases, the service is very profitable for renters and organization leaders but not for drivers. Therefore, some drivers do not join service organizations because they do not consider them helpful or beneficial at all. On the other hand, owners of the vehicles also cannot check the amount of money that the drivers make, which can lead to possible abuse of job agreements see [36,37,41,42,43,44,45,46].

In relation to the opportunities offered by informal transportation, in some cities (such as in Auchi, Nigeria; Bo-Town, Sierra Leone; Southwest Nigeria; Lomé, Togo; and in cities in Vietnam and Sri Lanka), ATSs have created many local employment opportunities; in the majority of cases, these have ended up being the main or the only opportunity available to the workers. Usually, those employment opportunities are directed to the less educated social groups in cities. Therefore, the service lets drivers earn ‘quick money’ in their daily life to meet basic needs. Employment provided by the service is usually taken by young males (19–38 years old), who are commonly school-quitters who find the work as a driver attractive, since it is time-flexible and usually provides an income above the minimum national wage level. In some cases, such as in Lomé, AT driver jobs are the most profitable informal job opportunity. In addition, the job could be used as a supplement to self-employment income. Furthermore, in some cases, such as in Southwest Nigeria, personal education level can help people earn a higher income within the informal transportation sector, which becomes as an incentive for working in it. This specific feature is stressed because the service is self-regulated by its organizations who hire and establish fares from their drivers. The rules of the organizations are basically related to vehicle registration and workers’ driving licenses. Therefore, in some cases, such as in Lomé, the service has low fares so that it can be purchased with small capital amounts. In some cities, such as Bo-Town, the service can be responsible for local violence proliferation, since it offers lots of employment opportunities see [34,35,37,38,41,42,44,47].

According to numerous studies, usually, it is recommended that informal transportation regulations should be limited only to safety, licensing, and indemnity standard aspects within a competitive market [48]. Yet the literature suggests that there is an imminent worldwide trend towards informal transportation increasing, meaning that extra specific standardized aspects should exist (see Table 2). Examples of these could be requirements for storage space in vehicles, creating exclusive road lanes, monitoring technologies, overseeing service app management, creating drivers’ unions, and making helmet use mandatory, among others see [36,37,38,44,49,50,51]. In the same way, it is important to prevent public policies related to informal transportation services that only provide grants and loans to service workers without taking administrative features into account. For example, the government issues permissions to work without completely regulating the administrative and organizational processes of the services. This is important because these policies tend to generate internal tensions between leaders and workers, creating more conflicts than they solve [43].

Nevertheless, regardless of the benefits and negative externalities caused by informal transportation phenomena worldwide, the governments of some cities have created and implemented public policies directed to their ATSs based mainly on previous regulations. Some policies have been successful in either increasing benefits or diminishing negative externalities, and others have not. This is because it is not effective to provide legality and treatment to these kinds of phenomena without the government giving concomitant permanent attention to them (see Table 2). Togo, for example, was one of the first countries to regulate the motorcycle cab service in 1996 by recognizing it as a necessary transport means. In Vietnam and Tanzania, the service was also formalized, with this first taking place in 2005. In other cases, regulation of the service is related to its organizations, such as in the case of Auchi, where motorcycle cabs are regulated by the Commercial Bike Riders Association.

In Rio de Janeiro, informal transportation means have entailed such a great social benefit that they have had to be regulated. Restrictions on the service have led to negative social and economic externalities on these systems see [34,35,37,43,50,52]. Fostering vehicle ownership for drivers as a governmental policy has helped to diminish inequalities between drivers, renters, and organization leaders. For example, in Vietnam, a business model has been executed based on individual implementation. In Lomé, Togo, some policies have been introduced that are meant to make it easy to buy service vehicles by providing financial help. Moreover, in Dar es Salaam, Tanzania, micro-credit grants have been directed to motorcycle cab service drivers see [34,37,43]. Other specific regulations of the service have included driver licensing and mandatory use of helmets (Lomé, Togo). In addition, drivers must pay several taxes and fees for implementing the service, and governmental inspectors also try to control their praxis (Kigali, Ruanda’s case) [37,53]. However, in some cases, such as in Dar es Salaam, Tanzania, the formalization of the motorcycle cab service has not alleviated its issues, since there has been constant lack of response from governments regarding issues directly or indirectly related to the service [43,49].

2.2. Alternative Transport Services Cases in the World That Relate to Mobility Potentials

According to the academic literature, there are aspects of ATS cases around the world that relate to mobility potentials, i.e., people’s potential to move based on their access to transport service choices [54]. Informal transportation is mostly used in urban centers. Usually, the centers of these cities are disorganized, meaning that their roads are in bad condition, and they have inefficient transport infrastructure, which leaves their transport systems unable to completely meet their mobile demand. Most commutes involve long-distance travel made by low-income social groups from the city peripheries to the center, mainly for working and studying. This is in response to historical territorial expansion (for example, in cities in Vietnam (xe om service); Auchi, Nigeria; Rio de Janeiro, Brazil; Jakarta, Indonesia; Manila, Philippines (bajajs, helicaks, bemos, and becaks services); Bo-Town, Sierra Leone; and in cities in Zimbabwe). In Vietnam, there is one motorcycle cab per 6.8 inhabitants. In addition, 5–11 percent of the total population trips use motorcycle cabs and this ATS is used mostly by students and workers but not in their daily activities [34]. There are cases, such as in Vietnam, in which most land use conditions of cities only allow AT vehicles to enter certain secondary roads. In addition, the mixed land use and high density of some cities’ centers have intensified internal short-distance travel undertaken by AT vehicles every day see [34,35,40,41,48,52,55].

Other cities (such as Jakarta, Indonesia (‘go-jek’); Manila, Philippines; Barranquilla, Colombia; Recife, Brazil; Caracas, Venezuela; and cities in Sri Lanka) have seen urban traffic congestion and lack of road hierarchy, such as collapses on bus services. Usually, motorcycles are more affordable than cars or buses, making them easier to buy. As a result, those characteristics have involved increasing on-demand mobility, which also makes it even more difficult to satisfy the commuting demand [38,44,48]. In some cases (such as in Auchi, Nigeria; Barranquilla, Colombia; Recife, Brazil; Caracas, Venezuela; and in cities in Vietnam, Zimbabwe, and Southwest Nigeria), the motorcycle cab service provides low-class groups with low-cost spatial mobility and connectivity to mass transport. For example, in the cases of Togo and Benin, the motorcycle cab service is cheaper than the regular taxi one [36]. Consequently, it also provides accessibility to city centers or peripheral neighborhoods. In most cases, the service covers main roads, road intersections, and local market areas. This means that some services, such as in Auchi, AT vehicles have stops along corridors (transit points) between localities. Consequently, the service tends to increase the street-level experience of travel see [34,35,38,40,42,56].

In other cities (such as in Jakarta, Indonesia; Manila, Philippines; Barranquilla, Colombia; Recife, Brazil; Caracas, Venezuela; Lomé, Togo; and in cities in Vietnam), informal transportation services are implemented that use small vehicles. These entail a balance between travel speed (higher speed than cars in some cases), a reduction in travel time, less time spent on loading and unloading vehicles, diminishing speed, and less frequently interrupted travel. Therefore, the service is mostly used for shopping or leisure (social trips), with an average distance of 5–10 km see [34,37,38,48]. In other cases (such as in Barranquilla, Colombia; Recife, Brazil; Caracas, Venezuela; and in cities in Vietnam, Togo, and Benin), ATSs can provide a door-to-door service. This is particularly useful and comfortable regarding mobility and it creates a preference for the service over other means of transport see [34,36,37,38,49]. Moreover, the use of technology has benefits for ATSs around the world. For example, in Sri Lanka’s case, cellphones are used for implementing the service, making drivers more independent. Furthermore, service fares are based on travel distance, but these tend to increase if it is late at night, raining, or if there are mid-journey stops on a trip. Hence, in Sri Lanka’s example, an average of 67 percent of the users are satisfied with the service [44].

As such, from the literature review of informal transportation, conclusions (recommendations) regarding ATSs that relate to possible policy making directed towards mobility potential can be drawn. These conclusions are the authors’ understandings after having analyzed the causes and consequences of the case studies. One of the main conclusions about worldwide informal transportation research is that it is not viable to dissolve these organizations because they are acknowledged as a complementary service. They provide interconnected transport means from city peripheries to centers and vice versa and also provide a high number of jobs (see Table 2). This way, the main challenge for formalizing informal transportation systems is preventing their social non-recognition as complementary transport systems in legal frameworks and including them in public policy implementation. Such policies should be designed with social participation and involve permanent monitoring of the service (provided only on secondary streets). Additionally, the policies should include revitalization of transport infrastructure, proper urban facilities and urban design, changes for sustainable vehicles, and fostering economic formal opportunities through competitiveness by individual and collective credit granting (to prevent monopolies) see [35,41,44,49,52,53,57,58], see Table 2.

2.3. Governance in Alternative Transport Services Cases: Access to Transport Planning and Workers’ Stigmatization

Within AT planning, governance involves stakeholders’ active participation in the processes of policy making and regulation creation alongside and transgressing governmental action [58,59]. In relation to the governance aspect, the literature review shows that ATS cases relate to the lack of access to transport planning and stigmatization of the social groups that work in those services. For example, some cases are characterized by a lack of formal job offers. This aspect was mainly favored by systematic economic policies that destroyed job creation, favored black markets, and diminished the force of workers. Some cases are more related to post-war periods, such as Bo-Town, in which it was mostly young ex-combatants who became involved in a self-integration process that made some of them become drivers of ATSs, owing to their lack of access to high social classes. Other cases, such as Rio de Janeiro, have also seen an increase in informal transportation due to urban congestion and rising public transit fares. Consequently, in those cases, there has been a correlation between being poor and working in the informal sector see [35,36,41,42,43,52,53,59] (this is the case in cities such as Bo-Town, Sierra Leone; Dar es Salaam, Tanzania; Rio de Janeiro, Brazil; and in cities in Togo, Benin (zemidjans service), Southwest Nigeria (okada service), and Uganda. In Lomé, Togo, 93 percent of motorcycle cabs used in the service come from China [37].

In other cities (such as in Dar es Salaam, Tanzania; Auchi, Nigeria; Kampala, Uganda (“boda-boda” service); Barranquilla, Colombia; Recife, Brazil; Caracas, Venezuela; Bo-Town, Sierra Leone; and in cities in Sri Lanka), there social stigmatization toward ATS drivers. This bad reputation is a response to various aspects of the service. For example, in the case of Kampala, drivers are disorganized and have certain political power, which has made them unrivaled within the social imagination of the city. Other examples are the cases of South America, where increasing pollution related to motorcycle use has stigmatized motorcycle cab drivers. Finally, there are other cases, such as in Dar es Salaam, where the government and society criminalize drivers by associating them with robberies occurring in relation to the type of vehicle they use see [35,43,44,53,60]. In Lomé, Togo, drivers of the service are associated with aggressive actions due to cultural aspects, such as the fact that most of them have been involved in past violence as army ex-combatants. Their violent actions are mostly confrontations with the police. Moreover, in Kampala, Uganda, drivers are in constant conflict with the local and central governments owing to the service-banning intentions of the latter [37,53].

Nevertheless, in some cases, the service leaders have managed to counteract the historical social exclusion internally by organizing the service. In some cities, organizations of the services provide their workers with an internal social care system, even though some are running outside legality. For example, in Dar es Salaam, the service leaders created NGOs to attend to their workers’ social care needs, and in Lomé, service employees receive basic facilities and social and professional assistance from their organizations [37,43]. Thereby, according to the authors of these studies, public policies directed to the service should be designed in conjunction with the public sector, academia, transport operators, and users (stakeholder clusters) [58], see Table 2. In addition, its market should be invested in by both public and private sectors.

Thereby, the aspects that pose a challenge to obtaining public transport policy features that should be considered are road congestion, use of public space, road safety, environmental conditions, the relation and balance between costs and use, economic security for workers, permanent governmental intervention, understanding of local cultural aspects, and lack of stakeholder skills [61]. Therefore, reaching a consensus between stakeholders could be difficult, so their different points of view with respect to the service will need to be taken into consideration to possibly create sympathy between one another [58]. This could help to foster customer care, organized transport systems, sustainability, and business ethics directed to the service see [36,38,40,51,59,62], see Table 2.

2.4. Micro-Mobility Service’s Externalities for Regulation and Policy

A considerable amount of the scientific literature on micro-mobility is based on quantitative research that measures travel efficiency, use patterns, user behavior and perception, market potential, and/or technological improvement see [24]. The same way, numerous studies draw on cases in the Global North and on e-scooter services, leaving aside cases in the Global South and (e-)cargo bike and e-bike services (see Table 1). According to some studies and reports, the main benefits of formal micro-mobility services are fast-tracking movements, transit accessibility, door-to-door service, responsibility-free ownership, private car reduction, ride-hail use, public transport avoidance [63], less occupied road space, and lower carbon footprint [64]. On the other hand, micro-mobility services tend to involve an irregular shared economy, as some have emerged without any previous governmental planning [61], with this boom starting in 2017 [65]. For example, in Denmark, this has entailed social problems, such as injuries caused by e-scooter-related accidents (it is seven times more likely to have an accident on an e-scooter than on a bicycle) [66]. Furthermore, some services that make use of (e-)cargo bikes and e-bikes have entailed exploitation and hard working conditions for couriers via outsourcing, and many delivery workers have gone on strike due to pay cuts see [67,68,69,70,71].

In the case of e-scooter services, they are often not attractive to seniors [72], children, or people with disabilities, and their users tend to be wealthier and more educated than non-users [73], which could suggest service use inequity, in contrast to e-bike services [74]. According to Mitra and Hess [72], the current literature on e-scooter services offers limited understanding of uptake-related environmental factors and the travel behavior of users, non-users, and potential users. However, a study that conducted an extensive literature review on micro-mobility posed that, in general terms, these services help cities achieve sustainable mobile praxes and even facilitate accessibility to products and services [24].

Micro-mobility services can also involve an irregular shared economy, as, for example, some people collect and recharge e-bikes and/or e-scooters without clear work regulations. People who replace their bikes with these vehicles miss out on the exercise they would otherwise undertake when biking or walking see [65,72]. Furthermore, the lifespan of the vehicles is 1–5 months when they do not receive proper care and maintenance, which makes the service a garbage generator in the mid-term and a CO₂ source in the long term [65], as was the case after China’s shared micro-mobility boom in 2015 [75,76].

In connection to user demand, in some cities (such as in Toronto, Canada; San Francisco, US; and Texas, US), docked sharing services tend to attract more users than dockless services, the same way as with electric services in comparison to non-electric ones [77]. Furthermore, the main challenges of dockless micro-mobility are parking demand and infrastructure improvements [78], although suburban areas have the potential to increase e-scooter service demand by paying attention to user behavior [72]

In some cities (such as in cities in Taiwan and Austin, Texas, US, and Minneapolis, Minnesota, US), e-scooter demand relates to environmental awareness and values, and they are largely used inside university campus areas [64,72,73]. Differently, in Germany, comfort is the main factor for e-scooter use and these vehicles are generally seen as entertainment rather than as an important transportation means [65]. Nevertheless, Bai and Jiao [73] attest that the urban environment determines micro-mobility service use and that proximity, accessibility, and even diversity of land use positively correlate with higher use. Travel efficiency and street safety are also added to these factors [65,72]. These factors indicate that service use is context-dependent, which is an important element to consider when planning and creating policies, regulations, and business models (see Table 1).

In connection with policy and regulation, some cities (such as Mexico City, Mexico; Chicago, US; and Portland, US) have used these micro-mobility services as the bases for technical pilot projects see [79,80,81]. Some local governments have coordinated with the national government, using its own and other countries’ experience, as well as with companies that provide the service. However, in spite of the fact that some companies and scholars have considered feasible sustainable and accessible options to improve the service see [82], the direction and approach of its further regulation and policy are uncertain and unclear in many cities [72]. From a technical perspective, Zakhem and Smith-Colin [78] suggest decision-making includes vendors’ homogeneous datasets in cities to ensure contextual accurate analysis results for territorial and environmental best practices. Additionally, Kopplin et al. [65] alert governments about the environmental footprint of e-scooters, challenging the commercial narrative that they are a sustainable transport means (see Table 2).

Mexico City, for instance, has dealt with e-scooter service challenges. In 2019, due to a lethal traffic accident where a taxi ran over an e-scooter user and the fact that some inhabitants in the center of the city complained about e-scooters blocking the sidewalks, the government of the city initiated the implementation of regulations to the service. E-scooters were allowed to park only in specific zones marked by signs on the sidewalks, each e-scooter company could offer only 856 vehicles, and e-scooters could travel with a maximum speed of 25 km/h. The government started charging the companies MXN 7200–14,000 (EUR 321–624) per vehicle as an agreed remuneration with the companies for parking on the sidewalks after a public auction [81]. Each company offered a yearly amount to pay per vehicle, and afterwards, the government set it up based on that. Companies are allowed to offer only 1750 vehicles (3500 in total) and e-scooters should not block the sidewalks. The government evaluates the service every three months. Hence, the logic behind the policy implemented in Mexico City is that e-scooter service companies should compensate the city as they make profit by using the public space.

The literature review helped gather information about ATS cases around the world that could provide the basis for understanding and diagnosing the phenomena with the aim of improving services and inspiring future research. The review demonstrates disparities between how research in the Global North and the Global South has been carried out, taking into consideration the geographical context of zones wherein the AT phenomenon has taken place.

Table 1. Research approaches on ATs between the Global South and Global North.

Research Approaches	Global South	Global North
Main methodological focuses	Governance, barriers, and opportunities for mobility potential, transport accessibility, workers’ stigmatization, and internal organization of transport services	Travel efficiency, use patterns, user behavior and perception, market potential, technological improvement, and regulation and policy
Main type of transport service	Motorcycle cab service	E-scooter service
Main status of the transport service	Informal	Formal

Table 1. Research approaches on ATs between the Global South and Global North.

Research Approaches	Global South	Global North
Main methodological focuses	Governance, barriers, and opportunities for mobility potential, transport accessibility, workers’ stigmatization, and internal organization of transport services	Travel efficiency, use patterns, user behavior and perception, market potential, technological improvement, and regulation and policy
Main type of transport service	Motorcycle cab service	E-scooter service
Main status of the transport service	Informal	Formal

Table 2. Contextual understanding of case studies of service policy and regulation on ATs between the Global South and Global North.

Service Policy and Regulation	Global South	Global North
Informal and Emerging Transportation	Policies and regulation should be designed with social participation and involve permanent monitoring of the service.	--
	Policies should include revitalization of transport infrastructure, proper urban facilities and urban design, changes for sustainable vehicles, and fostering economic formal opportunities through competitiveness through individual and collective credit granting.	--
Micro-mobility	It applies to some contexts of cities.	Policies and regulation should consider local and national governmental coordination, working according to cities’ experience, as well as with the companies that provide the service.
	It applies to some contexts of cities.	Decision-making should include vendors’ homogeneous datasets in cities that provide contextual accurate analysis results for territorial and environmental best practices.
	It applies to some contexts of cities.	Governments should consider and challenge the environmental footprint of micro-mobility vehicles, changing the narrative of these to assure transport sustainability. Finally, policies and regulation should take account of the fact that companies compensate the city relative to their public space use.

Table 2. Contextual understanding of case studies of service policy and regulation on ATs between the Global South and Global North.

Service Policy and Regulation	Global South	Global North
Informal and Emerging Transportation	Policies and regulation should be designed with social participation and involve permanent monitoring of the service.	--
	Policies should include revitalization of transport infrastructure, proper urban facilities and urban design, changes for sustainable vehicles, and fostering economic formal opportunities through competitiveness through individual and collective credit granting.	--
Micro-mobility	It applies to some contexts of cities.	Policies and regulation should consider local and national governmental coordination, working according to cities’ experience, as well as with the companies that provide the service.
	It applies to some contexts of cities.	Decision-making should include vendors’ homogeneous datasets in cities that provide contextual accurate analysis results for territorial and environmental best practices.
	It applies to some contexts of cities.	Governments should consider and challenge the environmental footprint of micro-mobility vehicles, changing the narrative of these to assure transport sustainability. Finally, policies and regulation should take account of the fact that companies compensate the city relative to their public space use.

3. Conceptual Discussion on Alternative Transport Services

As mentioned, the conceptual discussion in this study includes the terms paratransit, informal transportation, emerging transportation, and micro-mobility. I explain the differences within AT phenomenon based on contextual matters and processes between study cases. The comparative evaluation between those four types of transportation modes was chosen to create differentiations that attest understandings of the varied contextual processes of transport services within cities of the Global South and the Global North toward their possible individual planning, formalization, and sustainability. The same way, the discussion creates mediations between technical and (social) behavioral (contextual) understandings of the phenomena to consider research approaches and case studies’ policy and regulation differentiations.

3.1. From Paratransit to Informal Transportation

The paratransit transport types are those modes that people usually create in response to a certain lack of mobility potential to close mobility loopholes in the cities left by the transportation systems historically built by their governments see [48,57,83], see Table 3. I divide paratransit transport into two types: the personal and the (in)formal services. The first ones are those which people create, manufacture, or adjust according to their own mobile needs and desires. One example of these is Copenhagen’s cargo bikes called Christiania bikes (ladcykler). People started to use this transport means as a way of transporting persons (mainly partners, children, and friends) and to carry things that were difficult or impossible to move using a regular bike. For instance, Freudendal-Pedersen [84] mentions that ladcykler ‘serve specific needs that are most often served by cars’ [84]. The second paratransit type is the services that take place when a person or (self-)organized groups of people offer a transport service and make a profit. They do so with transport means that they have created, manufactured, or adjusted according to certain people’s mobile needs and desires, and their governments can regulate them. One example, continuing with Copenhagen, is its electric bicycle cab service (taxacykler) that its workers offer mainly to tourists in the city center. As the examples show, both types of paratransit could take place in the same city and context, and form part of its transportation and mobility systems as well. Therefore, paratransit services are transport modes that are considered the backbone of transportation systems as they meet the inner city’s mobility needs, for example, by providing door-to-door stops and fulfilling the first and last journey sections [48]. As a result, paratransit is estimated to make up half of total transport offerings worldwide (in Buenos Aires, 54 percent, in Calcutta, 41 percent, and in Sao Paolo, 23 percent [57,85]) and it is used satisfactorily most of the time (Al-Hasan et al. [35] consider the term ‘satisfaction’ related to transportation as the gratification achieved in the fulfillment of a need if expectations are met), mainly by students, the self-employed, and company employees with the dominant mode being motorcycle cabs [35] (Guillen et al. [62] explain that usually women and elderly people tend not to use informal transportation modes because of their lack of service quality). These transportation modes mainly provide seating capacity, speed variation, the capacity to carry objects, and geographical coverage, which together have become a basic right for people in a city. However, as mentioned, most paratransit cases have entailed lack of governmental acceptance and recognition, which is an important barrier for their regulation or prohibition. Therefore, the service usually involves irregularities that affect people directly and indirectly, as reflected mainly in road accidents, criminal activities, income inequalities within the sector, mismatching of supply and demand, over-tariff pricing, and non-tax payment see [35,40,44,45,48,51,57,60,62,85,86]. Under this logic, self-organized paratransit services as a business outside the legal terms of a city are what I call informal transportation.

Informal transportation provides on-demand mobility for those depending on transit, meaning that it also closes the mobility gap left by formal transport and non-satisfactory economic systems see [9,26,58], see Table 3. Usually, the main reasons for the creation of this type of service are the lack of fiscal and institutional capacity and an inability to meet journey demands by current formal transport in mainly under-served peripheral urban zones. In turn, those aspects involve a lack of services and products (and generally high criminal rates) see [44,51,57,87]. Additionally, informal transportation is categorized as motorized and non-motorized services, and there are three types depending on the volume of passengers they can carry: individual (1–4 passengers), shared (5–10 passengers), and collective (11–20 passengers) [44]. Furthermore, informal transportation users could end up being dependent on these services on a personal, household, and community level based on the quality of the service. As the main consequence, in time, informal transportation use turns into a habit, which is difficult to alter [62].

Governments do not usually address informal transportation services as they do not consider them to be a relevant phenomenon. Moreover, self-organized and self-regularized informal transportation services usually have a strong structure based on the loyalty and responsibility of the people involved in their organization see [37,44,51,53,57,58,61,88,89,90,91,92]. Hence, informal transportation is also characterized as stressing the role of social networks within its organization. It tends to involve diminishing costs and labor flexibility by creating client relations, started through social networking, between members of the organization and its leader based on protectionism and patrimonial logic [93]. Consequently, the leaders of these organizations tend to fight for the drivers, usually against their local governments, and, at the same time, provide administrative rules to their organizations see [9,36,41,44,58]. This way, within an informal transportation organization, there are mainly three types of workers related to vehicle use who provide the service as a production means. The first ones are called ‘work-and-pay’ employees (drivers whose work is intense and whose machines wear fast), the second ones are the ‘renters’ (they earn a low income, but enough to survive), and the third ones are the ‘earners’ or the ‘self-employed’ (they have high income, almost double that of the renters) [37,50].

Furthermore, informal activities are a response to social exclusion as a way, on the one hand, to drive the local economy and, on the other hand, to satisfy people’s needs for mobility. The creation of informal work favors local economies because, for example, the networks which organize the informal transportation service tend to distribute their income among the workers. Thereby, informal work generates jobs by fragmenting existing work, which subdivides the income [43]. The organizations therefore tend to coordinate not only the creation of alternative means of transportation but also the creation of economic flows inside the local zone among the inhabitants. People tend to be hired for informal work (as a main or complementary job) which, in turn, means they become part of the informal network of flexibility and negotiation. The social groups with less access to the city thus tend to create ways to travel differently from other groups that have more accessibility privileges provided by their government see [61,88,91,94].

3.2. Emerging Transportation and Micro-Mobility

From this research point of view, emerging transportation (for example, kombi-taxis in the extended city of Johannesburg that follow regular routes on the main roads because most jobs are in the suburbs of the city [13]) involves social groups that create their own means of transportation due to their spatial and socio-economic conditions, which relate to the social exclusion resulting from a historical urban segregation process (see Table 3). Hence, it is important to understand the emerging transportation phenomenon that people created and developed in informal ways of self-organization and self-regulation under a socio-historical background of territorial expansion. According to Sheller [95], mobility capabilities are the demands of social movements for rights of access to the city and transportation justice. In emerging transportation terms, service organizations have found, worked, and fought for their rights to work and move for decades and have usually tried to seek out governmental acknowledgement and attention for their service regularization. The actions of organizations tend to create additional potentials of mobility and economic activities that result in the contextual conditions of transportation and mobility systems. Moreover, mobility depends upon spatial fixities (arrangements) that relate to social and economic transformations. In this sense, the transformation of paratransit modes of transportation into emerging transportation networks mirrors the contextual economic, social, cultural, and even political characteristics of their cities. Those stages previously favored social arrangements to develop social conditions towards a more balanced accessibility between the different social groups expressed as social classes (divided into different zones of the city). This entire process is what, for example, peripheral zones in Mexico City have undergone for the past 25 years or so, and, as a result, currently, its motorcycle cab service workers are struggling to make the service a sustainable and formal one [58,61].

Emerging transportation is a phenomenon placed in the outskirts of a city due to an urban fragmentation process, and it responds to three kinds of people’s needs: job demand, spatial mobility [96], and connectivity to mass transport. The first need refers to the thousands of employment opportunities that the service entails, providing its workers with a relative sufficient income. In Tláhuac, Mexico City, Mexico, the monthly amount per worker is MXN 5520 (EUR 252.50) if they are owners of the vehicle, and MXN 1920 (EUR 87.82) if they are not the owners, which represents 33.3 percent of the total income created [61]. In Mexico City, the minimum monthly wage in 2014 was MXN 1884 (EUR 89.62) (CONASAMI, 2014). Therefore, the incomes of non-vehicle owner drivers were slightly under the minimum monthly wage in Mexico City by −2.28 percent. On the other hand, drivers who owned the vehicle had a monthly income greater than the average by +125.11 percent, which was a considerable difference in relation to the non-owners [61]. The second need involves (enchained) journeys to shop, visit family or friends, attend school, etc., which people perform inside the local zone (neighborhood). The third need entails maximization of mobility potentials that favors the possibility to connect people to fast mass transport, which involves appropriation of possibilities of movement, and it provides people with access to the rest of the city [97].

On the other hand, the term AT could refer to cases that have not necessarily undergone these emerging transportation processes—like Copenhagen’s ‘Christiania bikes’ (ladcykler), which respond to people’s needs in a different socio-historical, economic, and political context. Therefore, shared micro-mobility services are also ATSs. Micro-mobility involves the use of low-speed and electric transportation modes [77], and it ‘[…] relates to trips of shorter distance for personal transport by using light, small-sized vehicles or devices, particularly powered two-wheelers’ [64], see Table 3. Historically, the first to define micro-mobility as a term was Horace Dediu in 2017, who defined it as the ability of personal maximum freedom of mobility through minimalistic (the least impactful and heavy) means of transportation [98]. However, most of the scientific literature does not explicitly use and/or acknowledges his definition of the term, which stems from and was inspired by the computing field.

Micro-mobility services can substitute short trips (‘the last mile’: 1–6 km or more) conducted in conventional vehicles [72], although it can also replace walking [65]. Additionally, regardless of the latest development of the market and logistics systems of their service, (e-)cargo bikes respond to three kinds of needs: home delivery and transportation of goods, diminishing of pollution emissions, and job demand see [63,99,100,101]. Micro-mobility services tend to appear in both the Global North and the Global South as a formal transportation system, although their regulation tends to be concomitant to their implementation. Additionally, transnational companies from the Global North usually form the private sector of the service.

Non-electric micro-mobility is another category, which can be referred to as common cycling or other means of individual transportation, such as skates, mono-wheels, etc. see [25]. In the case of cycling, there is a considerable amount of research about it, especially in Global North cities, wherein it has become a lifestyle and a great part of politics and urban planning, such as in the case of Copenhagen and Amsterdam [27]. In the Global South, there are cases where cycling has also been a lifestyle under different circumstances more related to social stratification and poverty in under-served towns and neighborhoods [61,102]. An unresolved discussion in academic literature is whether cycling comes when implementing its infrastructure or cycling involves, as part of a culture, the infrastructure see [23,28]. I argue that contextual and multidimensional aspects of cities can shape such an understanding in cities. Finally, the academic literature does not refer to cycling as micro-mobility due to the term being well known and taken for granted in the field of transport planning and because cycling already existed before the term micro-mobility.

As mentioned, most studies on micro-mobility address e-scooters; however, micro-mobility services are not always e-scooter ones. In terms of this article’s argument, the e-scooter is not considered an emerging form of transportation. However, according to Zakhem and Smith-Colin [78], e-scooter services are an emerging transportation service—although the authors do not provide a theoretical explanation and justification for this statement. Moreover, Fitt and Curl [74] also consider e-scooter services as an emerging transportation service due to their temporality and spatial aspects. In this case, acknowledgement and the study of contextual social practices could be useful to develop research techniques aimed toward providing an equitable service. These aspects, however, do not align with the conceptualization of emerging transportation provided in this research and, therefore, e-scooter services are merely conceived as micro-mobility services within AT, together with e-bike and (e-)cargo bike services.

Table 3. Conceptual differentiation of ATs between the Global South and Global North.

Conceptual Differentiations	Global South	Global North
Paratransit	Modes that people usually create in response to a certain lack of mobility to close mobility loopholes in transportation systems; these are divided into the personal and the (in)formal services.	It applies to some contexts of cities.
Informal transportation	Provides on-demand mobility, closing the mobility gap left by formal transport services and the non-satisfactory economic systems.	It applies to some contexts of cities.
Emerging transportation	Paratransit characteristics that additionally involve a self-created transport service, mainly in response to historical social exclusion in a city.	--
Micro-mobility	It applies to some contexts of cities.	Shared electric micro-mobility refers to formal electrified services mostly created and administrated by transnational companies from the Global North that fulfill short, personalized trips at a city level. Some services that make use of (e-)cargo bikes and e-bikes fulfill home delivery and transportation of goods, diminish pollution emissions, and provide jobs.

Table 3. Conceptual differentiation of ATs between the Global South and Global North.

Conceptual Differentiations	Global South	Global North
Paratransit	Modes that people usually create in response to a certain lack of mobility to close mobility loopholes in transportation systems; these are divided into the personal and the (in)formal services.	It applies to some contexts of cities.
Informal transportation	Provides on-demand mobility, closing the mobility gap left by formal transport services and the non-satisfactory economic systems.	It applies to some contexts of cities.
Emerging transportation	Paratransit characteristics that additionally involve a self-created transport service, mainly in response to historical social exclusion in a city.	--
Micro-mobility	It applies to some contexts of cities.	Shared electric micro-mobility refers to formal electrified services mostly created and administrated by transnational companies from the Global North that fulfill short, personalized trips at a city level. Some services that make use of (e-)cargo bikes and e-bikes fulfill home delivery and transportation of goods, diminish pollution emissions, and provide jobs.

4. Conclusions

This study contributes to the transport planning field by acknowledging and differentiating research approaches, conceptual understandings, and contextual case studies for policy and regulation on AT in the Global North and the Global South. Hence, the findings of this research are summarized as follows:

4.1. Research Approaches

• A considerable amount of the academic literature on micro-mobility tends to be based on topics related to travel efficiency, use patterns, user behavior and perception, market potential, technological improvement, and/or regulation and policy. On the other hand, numerous studies addressing informal transportation and emerging transportation primarily focus on the governance, barriers, and opportunities of mobility potential, transport accessibility, workers’ stigmatization, and/or internal organization of transport services.
• A considerable amount of academic literature on micro-mobility draws on cases in the Global North and on e-scooter services, wherein there seems to be an unclear juxtaposition between micro-mobility and e-scooter conception, even though electric micro-mobility is remarkably diverse around the world. Therefore, micro-mobility case studies in the Global South and about (e-)cargo bike and e-bike services are limited. In this case, governmental and/or NGO reports offer information about this phenomenon. On the other hand, numerous academic studies on informal transportation and emerging transportation draw on motorcycle cab services in the Global South.

4.2. Conceptual Differentiations

• Services of micro-mobility, informal transportation, and emerging transportation are ATSs (considered due to their sustainability, active mobility, and human-scale characteristics) because they are an alternative to conventional transportation means, especially for fulfilling short trips in cities.
• This research defines the emerging transportation concept by differentiating it from paratransit, which refers to the modes of transport that people usually create in response to a certain lack of mobility to close mobility loopholes in transportation systems, and these are divided into the personal and the (in)formal services. The emerging transportation also has those characteristics, but it additionally involves a self-created transport service, mainly in response to historical social exclusion in a city.
• Informal transportation provides on-demand mobility, also closing the mobility gap left by formal transport services and non-satisfactory economic systems.
• The emerging transportation characteristic of micro-mobility that current academic literature offers does not align with the conceptualization of emerging transportation provided in this research because the former does not offer a clear conceptual theory. Therefore, on the one hand, shared electric micro-mobility refers to formal electrified services mostly created and administrated by transnational companies from the Global North that fulfill short, personalized trips at a city level. Some services that make use of (e-)cargo bikes and e-bikes fulfill home delivery and transportation of goods, diminish pollution emissions, and provide jobs. On the other hand, non-electric micro-mobility mostly refers to cycling (bike) although not in a direct way. In other words, there is currently vast research on cycling both in the Global North and South, but this is not actively acknowledged as micro-mobility, since cycling is currently a clear and trendy term in the field of transport planning.
• Micro-mobility, informal transportation, and emerging transportation help people fulfill mobile potentials in terms of accessibility to services and products in cities.
• These mentioned conceptual differentiations help researchers avoid generalization of understandings within AT phenomena in the Global South and the Global North, focusing on the multidimensional contextual place.

4.3. Contextual Case Study Understandings for Service Policy and Regulation

• ATSs are context-dependent. This is an essential element to consider when planning and creating business models, policy, and regulation.
• Policies and regulation for informal and emerging transportation should be designed with social participation and involve permanent monitoring of the service. Additionally, the policies should include revitalization of transport infrastructure, proper urban facilities and urban design, changes for sustainable vehicles, and fostering economic formal opportunities through competitiveness by individual and collective credit granting.
• Policies and regulation for micro-mobility services should consider local and national governmental coordination, working according to cities’ experience, as well as with the companies that provide the service. From a technical perspective, decision-making should include vendors’ homogeneous datasets in cities that provide contextual accurate analysis results for territorial and environmental best practices. Additionally, governments should consider and challenge the environmental footprint of micro-mobility vehicles, changing the narrative of these to assure transport sustainability. Finally, policies and regulation should take account of that companies compensate the city relative to their public space use.

Figure 1. PRISMA 2020 flow diagram for new systematic reviews which included searches of databases and registers only.

Figure 1. PRISMA 2020 flow diagram for new systematic reviews which included searches of databases and registers only.

4.4. Research Limitations

Lack of access to academic literature written in different languages other than English and Spanish limited the understanding of AT in contexts of other cities not addressed in this study. Therefore, this article does not necessary comply with all existent academic literature on passenger AT. Furthermore, restraining the choice of literature based on case study analysis in the Global South and Global North and method implementation could have meant important literature on the field of study were left out, which is another limitation of this paper’s findings.

4.5. Further Research on the Field of Study

On the one hand, this research’s findings can be used to inspire research, policy, and regulation for phenomena in zones of the Global North and the Global South, aiming toward AT green transitions and social equality. On the other hand, contextual multidimensional aspects of case studies can be considered for further research on the field of study to avoid generalizations on AT, which involve providing relative reflections on the research methodologies that are applied. Moreover, the conceptualizations resulting from this study can be applied in further research as a theoretical consideration to enrich the field of study and provide a more clear and concise understanding of the studied phenomenon.