Bridges and tunnels are essential structures that help people and vehicles cross obstacles like rivers, valleys, or mountains. A bridge is typically built above the ground, allowing traffic to pass over water or land. They come in various designs, such as arch, beam, and suspension, each serving different needs and environments. On the other hand, a tunnel is an underground passage that allows travel beneath obstacles. Tunnels are often used for roads, railways, and utilities, providing a safe and efficient way to connect areas without disrupting the surface. Both bridges and tunnels play a crucial role in transportation and infrastructure.