Good morning, everyone. Today we're going to discuss the history of urban transportation. In the early 20th century, many cities relied on electric trams, but by the 1950s, automobiles became dominant. However, a key turning point occurred in the 1970s when oil crises and environmental concerns led to renewed interest in public transit. For example, the city of Curitiba in Brazil pioneered a bus rapid transit system in 1974, which reduced travel times by 30% and inspired similar systems worldwide. Now, what was the main reason for the shift back to public transit in the 1970s?