Road bridges are structures built to span physical obstacles like rivers, valleys, or roads, allowing vehicles and pedestrians to cross safely. They are essential for transportation networks, connecting different areas and facilitating the movement of goods and people. These bridges come in various designs, including beam bridges, arch bridges, and suspension bridges, each suited for specific conditions and loads. Materials like steel, concrete, and wood are commonly used in their construction, ensuring durability and strength to withstand traffic and environmental factors.