Bridges and tunnels were important in eliminating the long way up and down in valleys and around mountains. Construction crews worked ahead of track-layers to build tunnels and bridges.
During the construction of the Transcontinental Railroad, the railroad company first built bridges with temporary trestles. Later, they were built using permanent and durable iron structures to support the stress of heavy loads. Digging tunnels was laborious and required thousands of workers to complete the task. Bridges and tunnels eliminated obstructions, such as valleys, hills and mountains, to allow connectivity across different regions.They provided clear routes by reducing the instances of winding railroads.