## 1 Introduction  
### Context  
In 2017, the United Nations established 17 sustainable development goals to achieve a more sustainable and peaceful world by 2030. In the specific case of public transport, target 11.2 was to provide access to safe, affordable, accessible, and sustainable transport systems for all. However, the starting point for this common objective is not the same in all regions, since urban public transport (UPT) has very different characteristics and level of use depending on many factors, among which socioeconomic ones stand out. For example, according to comparative studies carried out with data from the International Association for Public Transport, cities in Western Europe, the United States, and Oceania have UPT systems with better environmental and social performance, whilst developed Asian countries have more efficient services from an economic point of view due to the better level of vehicle occupancy and intermodality. On the other hand, Latin American regions have good public transportation systems from an economic operation perspective, although, as in Africa, transport can be very expensive considering average family incomes [1,2]. However, most studies show the importance of public subsidies for the poorest strata of the population [3]. Among other consequences, the COVID-19 pandemic has jeopardized these objectives of more sustainable urban transport, since most of the collective means of transport have not recovered the number of users prior to the pandemic in many countries. Thus, a global decrease in public transport demand between 16 and 39% remains despite the end of the main restrictions [4]. For example, in Norway, the percentage of recovered users was 83% at the end of 2022, whereas in Australia it was around 60% [5,6]. The main causes might lie in the sustained increase in telecommuting, the persistent perception of contagion risk, the modal change towards other means of transport, and the lack of adaptation of public transport to the new social reality. On the other hand, the decline in UPT demand in developing countries was much smaller, especially among the poorest segments of the population [7]. In this context, public managers in charge of the operation and management of UPT are promoting all kinds of measures to attract both the users who abandoned UPT during the pandemic, and those who, not having been users at any time, may be tempted to use it. However, given the large number of socioeconomic, urban pattern, governance, or quality service variables that influence the attractiveness of UPT, it is not easy to determine which measures might be most effective at this time. Within the broad spectrum of variables involved, this study tried to analyze the correlation between both qualitative and quantitative representative variables of the service operation (frequency, average vehicle occupancy, the length of the lines, urban or suburban route, circularity, nodality, and intermodality), and the average of users recovered by UPT compared to the year prior to the COVID-19 pandemic. This study was carried out in Almeria, a city of 200,000 inhabitants located in the south of Spain, since its intrinsically complex territory is covered by a municipal bus service of 16 lines which provides a very broad range of values for all the variables analyzed. Although it is difficult to draw conclusions from the analysis of a single city's transport network, the results obtained are expected to be of great interest to public administrations promoting sustainable urban mobility, since this study only focused on variables intrinsic to public transport, where the undertaking of short-term actions is feasible. This study is structured as follows. Firstly, a review of the existing literature is carried out, from general aspects such as the impact of the COVID-19 pandemic on UPT to those studies that have analyzed the role of specific variables of the service in this topic. Next, the data collected to perform the study are presented and the correlation obtained between the variables analyzed.