Pag 25

Pag 25

1. Background: Building bridges has been one of the most important tasks in connecting cities and countries. The Romans mastered the arch bridge and built hundreds of them all around Europe. The arch shape evenly spreads the weight down to the bases. They were so strong that many structures are still standing today.

2. Truss bridges were the first modern bridges. They use triangles instead of arches to spread out weight. The triangles can be grouped together, which makes them lighter and stronger than arched bridges.