Question

Why are the girders supporting the bridge not fixed in the walls of the pillars?

Answer 1

1. The girders used to support the bridges will expand on heating and contract on cooling.
2. If the girders are attached to the walls of the pillars, the walls will get damaged because of the expansion and contraction of the girders.
3. The girders are fixed on the rollers leaving a small space in between for expansion or contraction.