The object of crossing a bridge is primarily for transportation. Bridges serve as essential infrastructure that connects two points separated by a physical obstacle, such as a river, valley, or road. Their primary purpose is to facilitate the movement of people, vehicles, and goods across these barriers, thereby enhancing connectivity and accessibility.

Bridges play a crucial role in the transportation network of any region. According to the American Society of Civil Engineers (ASCE), there are approximately 607,000 bridges in the United States, covering a total length of about 43 million feet. These bridges are vital for economic growth, as they enable the efficient flow of goods and services, reduce travel times, and lower transportation costs. For instance, the I-405 Sepulveda Pass Bridge in Los Angeles, California, is a critical link in the region's transportation system, handling over 300,000 vehicles daily.

Moreover, bridges contribute to social connectivity by providing access to education, healthcare, and employment opportunities. The American Community Survey (ACS) reports that in 2019, 1.7 million people commuted to work across a bridge. This highlights the importance of bridges in supporting daily life and fostering community development.

Additionally, bridges can have significant environmental benefits. By providing an alternative to roadways that would otherwise require extensive grading or tunneling, bridges can minimize habitat disruption and reduce the need for new road construction. This is particularly important in areas with sensitive ecosystems, such as wetlands or mountainous terrain.

In conclusion, the object of crossing a bridge is primarily for transportation, as it connects communities, supports economic growth, and enhances social connectivity. The extensive network of bridges in the United States underscores their critical role in facilitating the movement of people and goods across various barriers.