## 3 Methodology
### Site of Study  
Braga is located in the north of Portugal and has a population of more than 190,000 inhabitants in an area of 183 km\({}^{2}\), which represents a population density of more than 1000 inhabitants per km\({}^{2}\)[60], distributed in 37 parishes (Figure 2). In Braga, 68% of the resident population is between 15 years old and 64 years old, which is the active population. In addition, 25% of the population is between 20 years old and 39 years old [60], which are the most representative ages for shared e-scooter usage according to the data presented in Table 1. The average monthly income of the population is EUR 1145.8, but for men, it is as high as EUR 1228.6, while for women it only reaches EUR 1033.6 [60].  
From 2001 to 2021 the elderly population in Braga (i.e., 65 years old or more) almost doubled, followed by a decrease of 2.5% in the population between 15 years old and 64 years old [60], which represents a decrease in the younger population and strong increase in the elderly population. However, the presence of higher education centers, such as the University of Minho, and research hubs, such as the International Iberian Nanotechnology Laboratory--INL, can stimulate the presence of younger people in the city while contributing to the diversification of the economy and the development of advanced services, as well as the promotion of newer, shared, and technology-based modes of transport [61].  
Figure 2: The location of the study site.  
In Braga, more than 170,000 commuting trips are generated daily, 84% of them within the municipality, which represents a total of more than 140,000 trips that are made by working individuals (66.7%), followed by trips made by students, which represent 33.3% of the displacements [61]. The most common modes of transport used in these trips are cars (69.7%), followed by walking (15.8%) and bus (10.3%) [62].  
In order to encourage residents to reduce the usage of cars for short-distance trips, the shared e-scooter service started its operation in the city of Braga in the second semester of 2019, with only one company operating about 80 e-scooters distributed around the city center, with expected expansion in the short term by the Municipality. In 2020 and early 2021, the service was shut down because of the COVID-19 mobility restrictions imposed in Portugal. In the first months of 2021, three different companies started offering about 500 shared e-scooters around the city center of Braga, and near the University of Minho campus in the parish of Gualtar (Figure 3).  
Figure 3 represents the actual area covered by e-scooter services in the city of Braga, encompassing only eight out of thirty-seven parishes in Braga. The parishes and their respective population are as follows: (1) Sao Jose de Sao Lazaro e Sao Joao do Souto (14,791 inhabitants); (2) Nogueira, Fraiao e Lamacacas (15,015 inhabitants); (3) Nogueiro e Tenoes (5946 inhabitants); (4) Gualtar (6761 inhabitants); (5) Sao Victor (32,876 inhabitants); (6) Sao Vicente (13,974 inhabitants); (7) Real Dume e Semelhe (13,682 inhabitants); and (8) Maximinos, Se e Cividade (15,087 inhabitants). The resident population in the area served by shared e-scooters corresponds to more than 60% of the total population in Braga.