Where is the exit of the railway bridge?

Usually on both sides of the bridge, at the bottom.

According to the Code for Urban Road Traffic Engineering (GB 55011-2021), the drainage outlets of railway bridges should be located every five meters on both sides of the bridge to facilitate timely drainage. Some railway bridges also need sewers at the piers for drainage.

There are many forms of water outlet, and the common ones are one-shaped, eight-shaped and door-shaped. The position, form and velocity of the outlet of the drainage channel should be determined according to the drainage quality, downstream water use, the range of water flow and water level change, dilution and self-purification ability, water flow direction, wave conditions, terrain change and meteorology.