## 4 Discussion  
Urban mobility is a key element for the economic and social development of cities, linked to the means of transport used (motorized or not) and to a set of externalities, including traffic congestion, correlated with the use of private vehicles and urban transport systems. In this context, urban transport is essential to ensure the social and economic well-being of cities, and the model that articulates order and fluidity and guarantees the comfort, saved time, economy and mobility of its inhabitants is, therefore, of very relevant importance. Prior to the COVID-19 pandemic, Latin American cities were among the most congested in the world. According to the INRIX(r) ranking published in 2019 [44], cities such as Bogota, Rio de Janeiro, Mexico City and Sao Paulo were ranked 1, 2, 3 and 5, respectively, as the most congested in a universe of 945 cities worldwide; in these cities, a driver loses more than 145 h a year sitting in his or her vehicle and the average speed is less than 21 km/h. However, in the publication of this ranking for the year 2020 [36], there is evidence of a decline in the rankings and hours lost, with driving hours decreasing by 31%, 69% and 66% in the cities of Bogota, Mexico City and Sao Paulo, respectively, as a result of the COVID-19 pandemic. Similarly, in [45] and for the year 2020, traffic congestion drops were reported, comparatively, with respect to 2019, in the cities of Bogota, Mexico City, Rio de Janeiro, Santiago, Sao Paulo, Brasilia and Buenos Aires with 19%, 16%, 14%, 13%, 15%, 15% and 11%, respectively. As an example, government restrictions in Colombia reduced demand on transport systems [46] and eventually changed the modes of transport used by the population, in efforts to try to maintain social distance. Many people decided not to use public transport and replaced it with private or non-motorized vehicles, such as walking or cycling [13]. Additionally, the total number of taxi trips in the areas studied in China declined sharply during the pandemic. This decline was most significant for taxi use during night-time hours, with no variation in average trip distances. The challenges of urban mobility in Latin American cities prior to the COVID-19 pan-demic were as follows [47]:  
* Public transport is the most used mode of transport (buses and micro-buses, with 102 million trips per day, followed by metros and trains, with 19 million trips per day), accounting for 42% of trips in metropolitan areas. However, public transport is of poor quality and travel time and cost for users are high;
* Road safety affects the most vulnerable (pedestrians) who account for more than half of all traffic fatalities (10,000 deaths per year);  
Figure 9: Percentage reduction (%) in traffic congestion (red) and urban transport use (blue), compared to the number of daily COVID-19 infections (gray). Rio de Janeiro, Brazil. * The level of pollutant emissions due to transport is very high in cities (260,000 tonnes of CO\({}_{2}\) and 3600 tonnes of other pollutants, such as CO and NOx), damaging public health;
* Traffic management is very limited, which prevents the optimization of the existing road infrastructure. Effective priority for buses, pedestrians and cyclists is very low. The figures previously introduced (Figures 2-9) show that the mobility restriction measures in the first months of contagion achieved a significant reduction in traffic congestion, being the lowest in the city of Lima with 87%. In turn, urban transport falls close to 90% for this same city. Table 3 shows a summary of the variables analyzed for all the cities considered. It can be recognized that as the number of daily infections has decreased there has been a recovery in the use of urban transport and private vehicles. Since urban transport is managed by the government, it is observed that its recovery happens slower than that of private vehicles, which is identified as the recovery of congestion. TCI has a higher correlation with infections than the use of urban transport.