The advantages of using steel in the construction of bridges over concrete and wood materials are:
Steel has a high strength,
There are types of steel that are resistant to weather, don't even need to be painted.
In terms of strength, steel is cheaper than concrete or wood, because with strength it requires less material volume.
Low installation costs.
Faster construction schedule.
High level of work safety.
Structural elements can be made in a factory, and can be done on a large scale.
Disassembly can be done quickly, without any material wasted.
Requires a narrower workspace.
Can follow architectural forms.
Environmentally friendly, can replace the position of wood as a construction material.