Which force is the pushing or squeezing force that creates inward movement toward the center and helps keep arched bridges standing?

• A. Compression
• B. Gravity
• C. Load
• D. Tension

Answer: (A)

Compression is the pushing or squeezing force that pushes neighboring pieces toward the center. In an arched bridge, every load causes the stones to press against each other along the curve, creating a horizontal thrust toward the arch’s center. This inward compression keeps the arch from spreading outward and allows it to carry weight effectively. Stone and masonry handle compression well, which is why arches are designed to rely on this type of force. Gravity is the downward force from weight, and load is the total external forces acting on the bridge, not the specific inward push that holds the arch together. Tension is the pulling force that would tend to stretch materials, not the inward push that stabilizes the arch.