## 1 Introduction
### Literature Review  
Mobility restrictions during the COVID-19 pandemic led to a significant decrease in the number of both long-distance daily trips [8] and those in metropolitan areas [9,10]. This general pattern especially affected the means of collective UPT, such as the bus [11], the metropolitan train [12], or the subway [13], reaching a decrease of around 90% in Italy and France, 85% in Spain, 75% in the United Kingdom, and 70% in Germany [14]. The number of users of urban taxis also had a very significant drop, by 94-96% [15]. Apart from these purely quantitative aspects, the impact of the pandemic on UPT was also qualitative, affecting modal choice [16]. Thus, within the general decline in mobility, a preference for means considered safer in that context, such as traveling on foot, by bicycle, or by private vehicle, could be clearly observed among travelers [17,18]. For example, the decrease in passengers on the subway in New York reached 90% compared to 71% in the bikesharing service, where the average travel time increased from 13 to 19 min, which shows the attraction of new users [19]. Moreover, during the toughest phase of the pandemic, the private vehicle was the preferred option within motorized transportation [20], even competing with traveling on foot as the main way to move around in countries such as Germany or Italy [21]. The process of returning to normality is also highlighting some significant data, showing mobility patterns somewhat different from those prior to the pandemic [22,23]. The most significant could be that UPT has not recovered the number of daily users prior to the pandemic, with a similar behavior in all collective means of transport [24]. Thus, although some of the infrastructure generated during the pandemic, for example, the bike-lane network, could help return to the path marked before the COVID-19 outbreak [25], many of the advances made in terms of sustainable urban mobility in recent decades are currently at risk [26]. As a whole, the share of trips that UPT lost has translated into an increase in those made on foot, by bicycle, as well as by private vehicle [27; 28]. In addition, there are other aspects influencing this change such as the emergence of new alternative means of transport such as electric scooters and bicycles [29]. However, the percentage of UPT users' decline during the toughest phase of the pandemic, as well as that of recovery in the post-pandemic phase, are influenced by numerous variables affecting both the supply and demand of transport. Among those variables, there are those of a socioeconomic nature, the availability of transportation alternatives, urban patterns, and the quality of the public service [30]. Logically, the impact of the pandemic on public transportation was also strongly affected by governance and regulations emanating from public authorities [31]. Thus, from a socioeconomic perspective, studies have shown that the decline in mobility during the harshest phase of the COVID-19 lock-down was greater in areas with higher income levels [32], linked to a greater ease for telecommuting [33] despite the greater availability of private vehicles [34]. In fact, the biggest shift from UPT to private vehicles has been associated with low-income areas [35], except in those with the highest percentages of captive travelers, i.e., those who do not have alternative means of transportation. This was the case in some regions of India, where no decrease in the use of public transportation was observed during the pandemic [36]. For its part, the recovery of travelers after the first wave of COVID-19 was greater in areas mostly inhabited by blue-collar workers [37]. From an urban pattern point of view, changes in users' behavior depend on variables such as density or the size of urban settlements, which undoubtedly affect the viability of the shift from UPT to non-motorized means of transport [21]. Urban zoning and the origin and destination of UPT lines have also been shown to be crucial factors in this field.