Micromobility and public transport integration : the current state of knowledge 2

Giulia Oeschgera, Páraic Carrolla*, Brian Caulfieldb 3 a School of Civil Engineering, University College Dublin, Dublin, Ireland 4 b Department of Civil, Structural & Environmental Engineering, Trinity College Dublin, Dublin, Ireland 5 6 * Corresponding author. Email address: paraic.carroll@ucd.ie (Páraic Carroll) 7 8 Abstract 9 Cities globally are grappling with the negative externalities of car travel and are therefore striving to move 10 towards a more sustainable urban transportation system. The introduction and popularity of new personal 11 transport modes, such as e-scooters or electric bicycles, could potentially accelerate this transition as they 12 become more commonplace and are accepted into regulatory frameworks. The integration of these new 13 modes and vehicles into public transport systems, for example, could enhance accessibility and lead to 14 potential modal shifts away from private car use. In order to assess the potential for change that 15 micromobility holds, it is key to study these new modes in the context of access and egress trips to and from 16 public transport. 17 This paper presents an extensive systematic literature review of studies that focus specifically on the 18 integration of micromobility and public transport systems and is, to the knowledge of the authors, the first 19 review focusing on this specific aspect of micromobility. This paper offers an understanding of how this 20 topic has been studied to date, which factors and aspects have been considered and analysed, which 21 causalities have been identified in the research, in addition to identifying gaps in the literature and providing 22 guidance for future research on this topic. Furthermore, this paper provides a comprehensive collection and 23 critical discussion of suggestions and recommendations included in the literature which are analysed in this 24 study, aimed at improving and further promoting the effective integration of micromobility and public 25 transport services. 26


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Micromobility is an exponentially growing new trend in urban mobility. Well-known, human-powered The main potential of micromobility in the urban context lies in solving the first-and last-mile problem by 1 improving access to public transport, and thus increasing access to services and opportunities, and similarly 2 contributing to changes in mobility patterns and behaviours, aimed at less car-centred urban mobility systems 3 (Holm Møller et al., 2019). The aim of this paper is therefore to provide an extensive overview of the 4 literature published in relation to micromobility and public transport integration, while also presenting the 5 state of knowledge in this field, identifying gaps in the literature and synthesising the findings, fundamentally 6 to investigate what type of studies have been conducted on the issue and how it has been examined to date. 7 The review is accompanied by recommendations and guidance for planners and practitioners in order to 8 improve and promote micromobility and public transport integration. The articles included in this systematic 9 literature review are predominantly centred on bicycles and bicycle sharing systems. This is due to the 10 novelty of other types of micro-vehicles and the lack of data on the integration of other micro-vehicles and 11 public transport. However, the findings from this systematic literature review will provide insights into 12 relevant aspects and valuable guidance for the analysis of all kinds of micro-vehicles when studied in 13 combination with public transport, in an integrated transport system. To the knowledge of the authors, no 14 review of this kind has been published as of August 2020. The systematic literature review presented in this 15 paper therefore constitutes an invaluable contribution to the current debate about micromobility and provides 16 insights and guidance on micromobility in the context of first-and last-mile access to public transport. 17 This paper is structured as follows: in section 2, the integration of micromobility and public transport will 18 be defined and introduced, to provide an overview of the topic studied; in section 3 the methodology 19 employed will be outlined, the results of which will be presented and discussed in section 4; while section 5 20 will conclude the article and provide an outlook for further research. 21 22 The integration of micromobility and public transport, if treated as a 'hybrid, distinct transport mode' (Kager 23 et al., 2016) and regarded as a single trip chain, can be considered a sustainable transport mode in which the 24 advantages of both modes can complement each other. Micromobility can offer flexibility and efficient door-parking in public spaces and on sidewalks, however, many cities have started to address this problem by 23 defining specific zones where dockless micro-vehicles can be parked. Table 1, the infrastructure and services needed for different types of integration differ. For the 1 examples (1) to (4), the main difference consists in the use of either shared or private micro-vehicles. If the 2 micro-vehicle is private, storage is usually required at both ends of the trip i.e. first or last mile trip, whereas 3 with shared micro-vehicles, the availability of such vehicles and the availability of free docks or designated 4 areas to park free-floating micro-vehicles is the most pertinent requirement.  22 The aim of this study is to determine the state of knowledge on the topic of micromobility and public 23 transport integration, not only to identify evidence of certain effects, but also to identify any gaps in the 24 literature that need to be addressed.

As shown in
A systematic literature review in four steps 1 The method used to conduct this systematic literature review was developed and adapted based on guidelines 2 presented by Thomas & Harden (2008) and the Transportation Research Board of the National Academies 3 (2015), which consist of the following four steps: 4 i. Designing the research process 5 ii. Conducting the research 6 iii. Analysing and extracting information 7 iv. Reviewing the findings 8 In the first step, the research goal and strategy were defined, including a clear and methodically documented 9 definition of search terms as shown in Table 2 and combinations of those terms in search strings, 10 identification of databases to be used, filters and inclusion and exclusion criteria on which to base the search 11 and selection processes.
12 Table 2 List of the search terms used to find relevant articles.  14 The research question that is at the core of this study is: How has the integration of micromobility and public 15 transport been studied and analysed to date? This question encompasses several other questions such as: 16 which aspects of the integration have been studied, which effects have been discovered, what 17 recommendations have been made in order to further promote the integration of the two modes? The aim of 18 this literature review is fundamentally to investigate what type of studies have been conducted on the issue and how it has been examined, while also providing an overview of the results and recommendations 1 presented in the literature as of August 2020. 2 It is important to note at this point that, in order to identify the most relevant articles, only those articles that 3 had the integration of micromobility and public transport at the core of their research question were selected. 4 This meant that articles that, for instance, analysed the multimodal behaviour of commuters including private 5 motorised vehicles or articles that focused on micromobility without considering its integration with public 6 transport were excluded. This decision was made as it was seen as more appropriate to select articles that 7 directly address the integration of micromobility and public transport to understand how the research is 8 framed in such studies and to determine the aspects of this particular topic that are studied. It is also worth 9 noting that, as micromobility is a relatively new concept, most studies identified through the literature search 10 focused on bicycle and public transport integration. As stated in the introduction, bicycles are considered 11 micro-vehicles based on the definition of micromobility adopted for this study, and it is safe to say that the 12 way in which cycling and public transport integration has been studied in recent years can provide relevant 13 insights, methods and starting points for research that will be conducted on the integration of other micro- 14 vehicles with public transport. In order to ensure the quality and relevance of the articles and studies 15 presented, only research articles from peer-reviewed journals were chosen. identified, and in particular on Google Scholar the vast amount of unrelated results presented challenges to 3 identify relevant articles. In addition to that, Google searches to identify grey literature on this specific topic 4 were conducted, using the keywords listed in Table 2, but no results were found that specifically consider 5 micromobility and public transport integration. The search process for each database was meticulously 6 documented in a research log, where information on search strings, number of results obtained, papers 7 selected or discarded with reasons and papers already previously selected were recorded. Each search process 8 was assigned a unique tag. Articles were selected based on their pertinence to the research question, by 9 reading the title and abstract. Articles that only marginally discussed the topic were not included. The 10 selected articles were then downloaded and imported to Mendeley, where a full text review was conducted.

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Each article was assigned a unique tag and a short summary of the main points was drafted. A further sifting 12 selection process was carried out at this stage, since not all papers that had originally appeared suitable were 13 actually considered relevant after a closer look. The reasons for exclusion at this stage were documented for 14 each paper. After this thorough and systematic selection process, a total of 48 articles were chosen to be 15 analysed in this systematic literature review. 16 In the third step, relevant information was extracted and documented for each article, such as the type of 17 integration studied i.e. types of micro-vehicles, type of public transport service; the city or country the study 18 focuses on (if any), the methodology used, etc. The articles were divided into two groups, (i) articles that 19 focused on shared micro-vehicles, and (ii) articles that focused on private micro-vehicles. This distinction 20 was made as it allows adding an ulterior layer to the analysis and discussion, given that most new 21 micromobility services are based on a sharing system, in order to understand similarities and differences 22 between these two types of concepts. In a first step of the analysis (section 2.1), all the relevant aspects of 23 the integration of micromobility and public transport that were considered in the literature were listed for each article, while in a second step (section 2.2), the suggestions and recommendations made in each of the 1 48 articles were collected and discussed. 2 3 The 48 articles selected for this systematic literature review were first divided into two groups: studies 4 pertaining to shared micro-vehicles and studies that focused on private micro-vehicles in combination with 5 public transport. In a first step, the types of integration studies and the case study areas (city/region) were 6 documented for each study. After that, to further specify the types of integration studied, the way in which 7 the integration process has been identified in each study has been documented, as well as the methodologies 8 used in each article. 9 To facilitate the analysis of the 48 articles selected, a grid was then created that includes all the aspects of 10 the 'micromobility and public transport integration' system that are considered most relevant for this 11 overview. These aspects are grouped into the following 4 categories: 12 Data sources 13 In this category a distinction was made between five different data sources in order to classify the articles 14 based on the data sources used. The data sources are: 15 (i) big data from public transport or micromobility providers; (ii) stated preference surveys; (iii) mobility 16 surveys / travel journals; (iv) local authorities, transport modelling tools, statistics, census; (v) interviews 17 or workshops with stakeholders and experts in the field of micromobility and sustainable mobility. 18 Depending on the data source, and therefore on the data used, the analysis and the results will be either more 19 qualitative or more quantitative in nature. Both insights are relevant in order to obtain a clear picture of the 20 system and can highlight the different dimensions of urban mobility and, in particular, the different aspects 21 of the integration of micromobility and public transport. In this analysis it was considered relevant to 22 understand what type of data sources were used when studying different aspects of micromobility and public 23 transport integration, which is why this category was included in the grid. All the aspects in this category significantly influence the functioning of the 'micromobility and public 10 transport integration' system, which is why it is relevant to determine which of these have been included in 11 the research so far, what impacts have been determined and what recommendations have been made in order 12 to improve and consolidate the system.

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This category lists the main user characteristics that have an influence on the 'micromobility and public 15 transport integration' system and that, if studied, can provide deeper insights into its functioning and on 16 measures or changes needed in order to promote it. Therefore, it is relevant to gain an overview of how these 17 characteristics have been studied and included in previous research and in combination with which aspects   It was considered relevant, within this study, to investigate which and how the impacts of the integration of 8 micromobility and public transport are studied and quantified. This is especially relevant to understand the 9 discourse used, the aspects that are considered relevant or the arguments that are proposed on this topic. 10 Focusing on relevant impacts and centring the discourse on those aspects that highlight the true potential and 11 beneficial effects of micromobility and public transport integration, allows presenting stronger arguments in 12 decision-making processes to improve the system. Only "what gets measured gets managed" and it is 13 therefore key to understand and measure all relevant impacts in order to further improve the system and 14 generate true change within the urban transportation sector. 15 Once these categories were defined and the grid was created, the selected articles were screened for each 16 one of those aspects. The according cell in the grid was marked if the paper included a certain aspect in the 17 analysis -it must be noted at this point that if one of the aspects was only briefly mentioned at some point 18 in the article, without it having any influence on the outcome or findings, it was not marked in the grid. The 19 rationale for the grid was to provide an overview of: (i) the different aspects of the micromobility and public 20 transport integration system that have been examined in recent years; (ii) the gaps present in the literature 21 that need to be addressed; (iii) which aspects have been studied in combination, and (iv) to comprehend how this system could be analysed in the future, including all classes of micro-vehicles in combination with 23 public transport. 1 In a second step of the analysis, in order to generate an overview of the main recommendations and 2 suggestions to improve the integration of micromobility and public transport made by the authors of the 48 3 articles selected, all the recommendations were collected and grouped into 6 categories. Two tables were 4 then created -one for shared and one for private micro-vehicles -to provide an overview of the types of All the specific suggestions made in each category are then presented and discussed more in detail. The 9 purpose of this step was mainly to present an overview for planners, practitioners and all other stakeholders 10 involved, of the insights already gained by research on this subject and to reflect and build on the 11 recommendations, in order to provide guidance on how to improve the planning process and implementation 12 of infrastructure, facilities and services that encourage modal shifts and changes in travel behaviour. 13 In the fourth step, the findings obtained from the analysis conducted in the previous step are discussed and 14 put into perspective, reflecting on the contribution this review makes while also considering its limitations 15 and ways to go forward. 16 17

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In this chapter, the results of the systematic literature review are presented and discussed. In the first section, 19 the 48 selected articles are reviewed based on the integration types, data sources, methodologies used and 20 aspects of the integration of micromobility and public transport studied. In the second section then, a review 21 and discussion of the suggesstions and recommendations made in the 48 articles are presented. In the last 22 section of this chapter, the main findings obtained from this systematic literature review are presented, as 23 well as the limitations and suggestions for further research. 1 The 48 articles that have been selected for this systematic literature review have been divided into two 2 groups: in the first group, the 24 articles listed in Table 3 focus on shared micro-vehicle services, mainly 3 bicycle sharing systems with multiple docking stations; in the second group, the 24 articles that focus on 4 private micro-vehicles, mainly private bicycles, listed in Table 4. In a first step, the type of integration studied 5 and the city or country the study is based in where identified. After, how the integration is measured and 6 identified has been documented, as well as the methodologies used in the 48 selected articles. These two 7 preliminary steps provide an overview of the variety of studies analysed and of the type of integration 8 studied, while also addressing the different types of methodologies used to identify and study intermodal trip 9 chains. 10 Types of integration studied and case study areas 11 Several of the articles in the first group compare the use of private and shared bicycles in their analysis,  Some of the articles in the second group suggest that the implementation of a micro-vehicle sharing system 2 could be beneficial to improve the integration of micromobility and public transport and also to promote and  When reviewing the types of integration studied and the sample areas and comparing the two tables, one 6 main difference becomes evident: in the first group (Table 3), several studies focus on Chinese cities, where 7 sharing systems are quite advanced and well integrated into the urban transportation network. Another reason 8 may be due to data availability in those cities, where the technology and the ticketing system have been  system integrated with public transport and therefore does not study an existing case but rather defines the 5 requirements for electric micro-vehicles, specifically designed for the integration with public transport. 6 When compared with Table 4, Table 3 appears much more homogeneous. Table 4 Rietveld, 2000), due to the popularity of bicycles and the availability of state of the art cycling 3 infrastructure. 4 In most articles in both groups, the focus lies on rail-based public transport -metro, train, tram/light rail 5 transit (LRT) -and while in some cases the studies include buses, especially in North and South America, 6 where rail-based public transport is not as developed and buses or bus rapid transit (BRT) systems are much 7 more common, high-speed and high-capacity public transport services are predominantly at the centre of  How the integration has been studied 14 Another relevant aspect that has been analysed in this systematic literature review is how the integration 15 between micromobility and public transport has been studied and identified. Studying integrated trip chains 16 is not trivial and identifying and selecting data on intermodal travel behaviour requires specific 17 methodologies. As can be seen in Table 5 and Table 6, there are several ways in which the integration can 18 be studied. The most common and arguably the easiest method is to use a survey and get the information 19 about the integration practice or preferences from the respondents. For shared micro-vehicles, as can be seen 20 in Table 5, big data from bicycle sharing companies can be used -namely GPS data of start and end locations, 21 trip duration and information about the users. To identify those trips that serve as access or egress for public 22 transport, however, further steps are necessary. Usually the trips are selected creating a buffer around public 23 transport stations, and those micromobility sharing trips that start or end within that buffer are considered 24 access or egress trips. This method is most commonly used in studies pertaining to dockless bicycle sharing   . In these studies, bicycle sharing trips that start or end within 300m of a metro 7 station are selected and subsequently matched with metro trips by the same users that have started or ended 8 within 10 min. This means that the transfer process at the metro station has to take 10 minutes or less for the 9 trip to be considered in the analysis. Spatial data analysis is sometimes also used to model and determine the 10 potential for micromobility and public transport integration, based on factors such as the public transport 11 network characteristics, available infrastructure, built environment. This kind of analysis can be used to 12 compare different scenarios and predict the potential for micromobility and public transport integration in a 13 given area, under specific circumstances. In some of the studies, as can be seen in Table 6, a combination of different methods was used to determine the levels of integration between micromobility and public 1 transport: information obtained from surveys was combined with spatial data analyses of the public transport  Table 6 conducted a conceptual 5 analysis, meaning that they did not specifically identify integrated trips. In these studies, the concept of the 6 integration of micromobility and public transport was studied as such, taking the integration of the two modes 7 as a given. . 8 Table 6 How the integration has been studied in articles about shared micro-vehicles and public transport As well as the data collection types and methodologies used to determine the integration of micromobility 11 and public transport, the methodologies used to answer the research question in each of the 48 selected 12 articles were reviewed and are presented in Table 7. A variety of different methodologies were used in the 48 articles reviewed in this study. A significant number of articles, as shown in Table 7, are based on findings 1 from regression analyses and several studies use GIS-based spatial analyses to determine different aspects 2 and spatial characteristics of the integration of micromoiblity and public transport. Many studies presented 3 in Table 7 centre the enquiry on accessibility analyses, to determine how the integration of micromobility 4 and public transport influences access to public transport and to services and opportunities. In particular, as 5 shown in Table 7, a number of studies use inequality indices and equity analyses to determine the social facets that characterise the integration of micromobility and public transport, it is necessary to study and 16 approach the topic from a range of angles and viewpoints. Aspects of micromobility and public transport integration studied 2 The grid presented in Table 8, which includes all 48 articles selected for this study divided into the two 3 groups of either shared or private micro-vehicles, provides an overview of the different aspects and 4 characteristics of the micromobility and public transport integration system studied. 5 Data sources 6 In the data sources category, it can be seen that most studies rely on stated preference and mobility surveys 7 and data from transport modelling tools or from local authorities for the analysis. Big data volumes from type of qualitative data requires a significant amount of time and resources and these data are very case 10 specific, since it is usually limited to a particular vehicle or small area. Nevertheless, in order to gain a full 11 perspective of the system, it is important to acquire knowledge and information at all scales and levels, 12 including the very personal and detailed information that can be gathered during workshops or in workgroups 13 of experts. As discussed further in section 3.2, it is crucial to include all stakeholders early on in the planning 14 process, in order to take into account all the different aspects that are relevant to different actors in the system, 15 namely the local authorities, public transport and micromobility providers, and especially the users. 16 System characteristics 17 When it comes to the system's characteristics, the built environment, micromobility infrastructure and the 18 facilities for micromobility at public transport stations play a major role in most studies. Since these are all 19 factors that significantly influence people's propensity of using micromobility as an access mode to public

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Another important factor is accessibility. When analysing the integration of micromobility and public 18 transport it is crucial to understand how accessible public transport stations are, how well sharing services, 19 micromobility infrastructure and facilities can be accessed and how well these provide access to services and 20 opportunities within a given time. This is particularly relevant when analysing mobility patterns and user 21 behaviour, to understand the inequalities in level of access. By addressing these elements, a more equal 22 service that fosters social inclusion can be provided, which can help marginalised groups to become more Four of the articles in Table 8  & Tamenei, 2020). As can be seen in Table 8, the costs for users that integrate micromobility and public 4 transport have been included in 12 of the 48 studies, given that costs, particularly of sharing services and 5 parking facilities, can be a determining factor of modal choice and as such can often act as a barrier. As will 6 be discussed in section 3.2, incentives and discounts are often suggested as a strategy to attract new users 7 and to include marginalised population groups. 8 The presence or introduction of policies in favour of micromobility and public transport integration has been 9 considered more often in studies concerning private micro-vehicles, and is often related to policies and 10 regulations that allow micromobility users to carry their micro-vehicles on board of the public transport 11 service or bike-and-ride policies that facilitate the integration of the two modes. In the studies concerning 12 shared micro-vehicles -the policies and regulations considered pertain to the improvement of cycling 13 infrastructure and the implementation of safe and protected cycling lanes (see Table 8).
14 In this category, the grid ( Table 8) also displays that some aspects of the system that are relevant for the use 15 of shared micro-vehicles are not relevant for the use of private micro-vehicles. For instance, the location or 16 distance to sharing stations and therefore the access to micro-vehicles, vehicle requirements and the costs of design of electric micro-vehicles for a sharing system for access and egress trips to and from public transport. 23 24

Users
Regarding user characteristics, demographic and socio-economic attributes are included in most studies since 1 this information can be obtained from surveys and from census data or statistics provided by local authorities. 2 This type of data is often also included in big data from public transport or micromobility providers, as is  Table 8, also consider the mobility patterns of users, to try to uncover the interdependencies of modal 6 choice and the spatial extent and reach of each mode within the intermodal trip chain. When trying to 7 understand the behaviour of users that integrate micromobility and public transport it is relevant to 8 understand how and when they choose to integrate these two modes and for what types of trips. 9 Approximately 25% of all the studies considered also include preferences and reasons for modal choice in  The reasons and factors that influence modal choice are key as they can often pose a barrier for new users to 16 try a vehicle or mode that they perceive to be unsafe or that they associate with a certain type of user 17 behaviour. In Zhao & Li (2017), for example, it is mentioned that cycling is associated with low-income 18 groups in Beijing, and many users avoid cycling because of its negative image and links to societal status. In the final category, the impacts of the integration of micromobility and public transport are listed. By 23 examining Table 8 it is evident that the impacts do not feature in the analysis in most articles. Most articles 24 mentioned some of the benefits or effects of micromobility and public transport integration in the introduction, literature review or conclusion, but the impacts do not form part of the analysis, and the impacts 1 were not calculated or quantified in any way. As can be seen in the columns on the right of the grid in Table   2 8, the impact that has been quantified the most (in 9 out of 48 articles), is the modal shift that can be expected 3 from the improvement of the micromobility and public transport integration system. 4 Seven of the selected studies in Table 8  integration of a bicycle sharing system with the metro network, and considered cost and economic impacts 15 of the integration, while also calculating CO2-emission reduction following modal shifts from private cars 16 as an environmental impact/benefit. 17 18 The grid in Table 8 clearly shows that there are gaps in the literature that need to be investigated and 19 combined with previous findings in order to fully understand the system and implement changes that can 20 lead to more sustainable mobility systems. Particularly in relation to the impacts, it is apt to further analyse 21 the impacts that the integration of micromobility and public transport has on a social, economic and    1 The suggestions and recommendations made by the authors of the 48 selected articles have been grouped 2 into six different categories, dependent on the issues they address. As outlined in Table 9, in both groups, 3 for both shared and private micro-vehicles, the majority of suggestions made are in relation to infrastructure. 4 For shared micro-vehicles, suggestions regarding vehicles, technology and data, and about policies, 5 regulations and incentives have been made in several articles, while for private vehicles aspects regarding 6 planning are mentioned frequently. The specific suggestions brought forward in the articles will be presented 7 and discussed in detail in the following.  Most studies stress the importance of a safe, comfortable and continuous network of dedicated and protected found as the maximum distance that users are willing to walk to access public transport after returning the 12 shared micro-vehicle. 13 14 Another recommendation that many studies offered is to implement traffic calming measures and regulations stations, particularly at the destination locations, can exclude certain population groups and limit equal 10 access to the service, which is a factor that should be considered when the spatial distribution of sharing 11 stations is planned. Some papers suggest that, in countries with high degrees of inequality in terms of access 12 to public transport, in addition to micromobility infrastructure, further investment in transit in low-income   however, mention that local authorities should be wary of making reference to findings from other cities 12 when it comes to the influence of built environment characteristics and shared micromobility use. Empirical 13 data collection of local knowledge and preferences is suggested as the best option.

Review of suggestions and recommendations
14 Rietveld (2000) suggests that non-residential, high density land-use types should be prioritised in the 15 surroundings or railway stations, such as offices, education, shopping and cultural facilities to promote active 16 travel modes and micromobility as access and egress modes. 17 18 Technology (Vehicles/Apps/Real-time data) 19 Technology plays an important role since it can significantly improve and facilitate the integration of is the main factor that influences propensity to use share micro-vehicles to access public transport stations. 6 For users that want to transport their micro-vehicle on public transport, real time data on available spaces on   In order to promote and further improve the integration of micromobility and public transport, the two modes 21 should be considered as one system and accordingly, should be planned and developed together considering short-term effect in promoting modal shifts away from private cars. 2 3 Pricing and incentives 4 Pricing and incentives such as flexible and integrated ticketing, discounts for specific user groups and 5 incentives for users that integrate frequently are additional instruments that can be used to promote 6 micromobility and public transport integration, to attract new user groups and promote social inclusion and 7 equal access to services and opportunities. The introduction of uniform ticketing systems for micromobility 8 and public transport systems would not only allow for a more user-friendly experience but would also make 9 transfers more efficient, convenient and, moreover, it would provide important insights into mobility patterns 10 and behaviours (Böcker et al., 2020). This in return would provide the basis for improvements and planning 11 guidelines. 12 Various studies emphasise that a flexible pricing system should be introduced to incentivise rides outside of  policies that discourage the use of cars for short trips could be examined, for instance a pricing policy for 3 park-and-ride that is proportional to the inverse of the distance travelled by car, to encourage people that live 4 close to the station to choose micromobility as an access mode (Midenet et al., 2018). Alternatively, to 5 promote micromobility and public transport use for trips to work, employers should be encouraged to reward 6 employees that use micromobility and public transport for trips to and from work, via a program that promoting the integration of micromobility -including private micro-vehicles -and public transport. 20 However, it is worth noting that in certain contexts and under specific circumstances, it can be useful to 21 consider the advantages that a shared micro-vehicle system could have compared to the use of private micro- 22 vehicles. For instance, a shared system has the advantage of requiring less vehicles and therefore less space, 23 since vehicles are shared among different users. Nevertheless, it would be prudent to first and foremost 24 promote modal shifts from private motorised vehicles to micromobility and public transport by improving 25 conditions for both shared and private micro-vehicles. 1 Training & educational campaigns 2 In order to raise awareness and promote the integration of micromobility and public transport, especially as

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(2020) state that it is important to promote micromobility among the younger generation to change the image 12 of micromobility use, given that many young people use it out of lack of alternatives and for financial reasons 13 and tend to abandon the mobility practice once they can afford a different mode of transport. As an additional    21 In the first step of the analysis, the main gaps in the literature were identified: while most studies were 22 conducted to identify the reasons, preferences and mobility patterns of users that combine micromobility and 23 public transport, most articles did not include the impacts that the integration of micromobility and public transport has on society, the economy and the environment. Of the studies observed, few included an 1 examination of an impact in their analysis, quantified by means of modal shifts from private motorised 2 vehicles to micromobility and public transport that can be expected from improvements to the system. A 3 limited number of studies focused on the social impacts that the improved integration of micromobility and 4 public transport have, such as promoting social inclusion, reducing inequalities between and among different 5 population groups and increasing the access to services and opportunities. However, none of the 48 articles 6 selected included and quantified the impacts that an effective and successful integration of micromobility 7 and public transport could have on the environment, on liveability and sustainability and on the economy, 8 and this was found to be the most significant gap. It is vital to include these aspects in future research, to 9 provide evidence of effects, in order to make stronger arguments for the implementation and improvement 10 of such an integrated transport system. While some data may be available on these issues when considered 11 on their own -such as, for example, a life cycle analysis of e-scooters, as presented by Holm Møller et al. and contribute to climate change. It was concluded that such findings need to be investigated further and put 18 in the context of other cities and more specifically, in the context of the integration of micro-vehicles with 19 public transport for longer trips. Another evident gap is the lack of research focusing on new and electric 20 micro-vehicles in the context of integrated transport. Due to the fact that these vehicles are new, and data is 21 only scarcely available, analysing the integration of these vehicles with public transport can be a challenge. 22 However, in order to gain a more complete understanding of the potential of such integrations, these micro- 23 vehicles need to be studied in the context of an integrated transport system, as access and egress modes to 24 and from public transport. with motorised traffic, that should be contained and slowed down through traffic calming measures. As also 10 stated in the ITF report on Safe Micromobility (2020), motorised vehicles are involved in 80% of fatal micro- 11 vehicle accidents, meaning that reducing the potential for conflicts between the two modes can drastically 12 improve safety for micromobility users. Given that the goal is to improve and promote the integration of 13 micromobility and public transport, the infrastructure, facilities and amenities for micro-vehicles at public 14 transport stations and stops should be improved and implemented for this purpose, to provide a safe, 15 comfortable and user-friendly service that can compete with private motorised vehicles. 16 17 Characteristics of the built environment surrounding public transport stations also significantly influences 18 the modal share of micromobility as an access and egress mode and should therefore be considered when 19 planning and implementing measures to promote the integration of micromobility and public transport. The 20 importance of data collection and analysis to further understand the different aspects of the integrated 21 micromobility and public transport system was mentioned, also stressing the positive impacts that real-time 22 data could have on users' experience and satisfaction of the integrated transport system. 23 Relevant suggestions were also made concerning planning and implementation of infrastructure, measures 1 and micromobility sharing services. The importance of cooperation and collaboration among all involved 2 stakeholders, including users and local communities, throughout all the planning phases was mentioned as a 3 relevant ingredient for a successful integration of micromobility and public transport, as well as for 4 identifying vehicle requirements and user preferences. 5 With regards to social inclusion and equity, it is recommended that these aspects are considered from early 6 on, in order to plan and implement a system that guarantees equal access to all population groups, while also 7 improving social inclusion and providing access to services and opportunities to those user groups that tend 8 to be marginalised or excluded. This aspect is relevant when planning new measures or infrastructure, but it 9 can also be improved via incentives and subsidies. It is recommended, that local authorities and service 10 providers attempt to increase ridership among those user groups by facilitating access to the combined use 11 of micromobility and public transport services through incentives and discounts. Additionally, in order to 12 help different user groups to overcome the barriers that hinder them from using the integrated transport 13 system, educational campaigns should be used, and trainings should be provided.  19 and practitioners that wish to improve the integration of micromobility and public transport.  22 Micromobility has significant potential to contribute to a more sustainable and socially inclusive urban 23 transport system when combined with public transport services. However, to harness its potential benefits, 24 more empirical research is required to address the gaps identified in this systematic literature review. More measures and improvements need to be implemented following the findings that are already available and 1 those that are presented in this article. In particular, the authors suggest three main fields of enquiry that need 2 to be addressed by further research on this topic: (i) the impacts of an integrated transport system that 3 combines micromobility and public transport, in particular the impacts on the environment; (ii) the 4 integration of different types of micro-vehicles and public transport such as, for example, shared and private 5 e-scooters and e-bikes and the implications for infrastructure requirements for these different types of 6 vehicles; (iii) the development and use of specific methods for data collection and analysis of micromobility 7 and transport integration, to better understand the practices and mobility patterns of micromobility and public 8 transport users. These three aspects will be discussed in more detail in the following. 9 Environmental, social and economic impacts 10 The main aspects that should be considered in further research pertain to the impacts that an integration of 11 micromobility and public transport would have on the environment, society and the economy. This review 12 has suggested that in particular the impacts on the environment should be examined more closely and in 13 greater detail, specifically in the context of an integrated transport system. The successful integration of 14 micromobility and public transport can promote mode shifts away from private cars in the urban and 15 suburban contexts and can therefore be a valuable instrument to decarbonise transport and reduce the 16 environmental impacts of the transport sector, while also contributing to more liveable and healthier cities. 17 The environmental benefits of integrated transport should therefore be studied and closely monitored, to 18 provide guidance and evidence to support decision-making processes. In addition, clear and quantifiable 19 environmental impacts and benefits of an integrated transport system -such as CO2-emission reductions or 20 air quality improvements due to mode shifts away from private cars -could be used to promote and 21 incentivise integrated transport systems and encourage even more users to integrate micromobility and public 22 transport in their daily mobility. 23 In the same way, quantification of the impacts on society would also be a welcome addition to the knowledge 24 base, in particular social equity and accessibility to services and opportunities across different population groups. The contribution of micromobility and public transport integration in this area could further increase 1 the importance and priority given to measures and infrastructure that promote social inclusion and have 2 overall positive impacts on society. Many cities have set themselves goals to become more equal and 3 inclusive and the contribution of micromobility and public transport integration on this matter has to be 4 studied and documented. For this reason it is relevant to analyse and quantify these impacts and address 5 these issues in the planning and development phase of infrastructure and services to integrate micromobility 6 and public transport. 7 The impacts that the integration of micromobility and public transport has on the economy in a specific urban 8 context could also provide valuable insights and contribute to the current debate in relation to solutions to 9 implement a successful and efficient integrated transport system. In particular when considering the cost-10 effectiveness of an integrated transport system and of different measures that promote and facilitate the 11 integration of the two modes, it is extremely relevant to quantify and discuss the economic impacts. Such 12 considerations must also include the other impacts listed above, such as environmental and health impacts, 13 as well as social impacts, that can all result in substantial economic benefits for cities. 14

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Different types of micro-vehicles 17 Additionally, different micro-vehicles ought to be considered and studied in the context of first-and last- new vehicle types need to be studied and the necessary services and infrastructure required to seamlessly 22 and successfully integrate these vehicles with public transport need to be defined and planned. The 23 integration of electric micro-vehicles with public transport requires additional considerations regarding 24 environmental impacts. While electric micro-vehicles are more energy efficient and use less space than conventional cars and electric vehicles due to their size, there are still aspects that need to be considered, 1 such as the production and end of life phase of such vehicles as well as considerations regarding use of such 2 micro-vehicles in combination with public transport. For shared micro-vehicles in particular, charging and 3 redistribution systems and strategies need to be put in place to minimise environmental impacts and 4 implement a truly sustainable alternative transport system. In order to further reduce the environmental 5 impacts of the combined micromobility and public transport system, also public transport options should be 6 evaluated and promoted based on their energy efficiency and environmental impacts. 7 Data collection and analysis 8 Going forward, new methods of data collection and analysis are needed, in order to more accurately model 9 intermodal trip chains, mobility behaviours and patterns and the spatial reach of integrated transport systems 10 combining micromobility and public transport. Furthermore, introducing integrated ticketing systems and 11 improving transfers at public transport stations -through improved parking facilities and services -would 12 make the user experience more convenient, pleasant and reduce overall travel time, while also providing 13 valuable data. User centred research and design should be used to identify the main aspects that require 14 improvement and to obtain insights into the users' experience and practices. These insights could then be 15 used to inform planning strategies and developments to further promote and incentivise modal shifts away 16 from private cars, to additionally reduce the environmental impacts of urban transport systems and improve 17 liveability in cities. 18 19 The global pandemic caused by COVID-19 has forced cities worldwide to rethink and reimagine their 20 strategies to promote and enable sustainable mobility also in order to ensure that social distancing can be 21 maintained. With this in mind the process of assessing and regulating the use of new micro-vehicles should 22 be accelerated in respect of the evident demand for such micromobility trips. This review has highlighted 23 that the importance of infrastructure provision for micromobility and active modes and why it should be adapted and improved, while more road space should be allocated to sustainable modes and pedestrians, to 1 ensure compliance with the social distancing requirements.

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In this paper, a systematic literature review was conducted, to find out how the integration of micromobility 5 and public transport has been studied to date. Through a systematic approach, 48 articles have been selected 6 and analysed in this study, that specifically focus on the subject of micromoblity and public transport 7 integration. The main goal was to identify the aspects of the topic that have been empirically examined to 8 date, while also discovering the gaps that exist and ought to be addressed in order to fully appreciate the 9 system and further improve it. In a second step, the main recommendations and suggestions from the 48 10 articles were collected and organised into categories, in order to underline the main issues that could be 11 addressed and to provide some guidance for planners and practitioners, seeking to implement measures to 12 improve the integration of micromobility and public transport. The main gaps that could be identified pertain 13 to the impacts that the integration of micromobility and public transport has on various aspects of society, 14 the environment and the economy. These require further investigation, in order to generate a better 15 understanding of the benefits and limitations of the integration of micromobility and public transport. 16 Moreover, studies which conduct data analysis on how micromobility is used as an access and egress mode 17 to public transport is welcomed, as this was a gap identified in the literature. This is particularly true for new, 18 electric micro-vehicles that have not been extensively studied in the context of an integrated system with 19 public transport yet. The paper also provides an overview of recommendations and suggestions included in 20 the 48 articles reviewed. These recommendations address several aspects of the integration of micromobility 21 and public transport and provide guidance to those seeking to implement measures or improve the conditions 22 that facilitate and promote the combined use of micromobility and public transport. 23 This systematic literature review was conducted in accordance with a strict methodology, and search and 1 selection process, aimed at identifying the state of knowledge on this topic of micromobility and public 2 transport integration. However, the authors accept that naturally some articles may have been missed and 3 therefore were not included in this review. Nevertheless, the selected articles provide a solid and extensive