Aluminum is a non-corrosive metal because it naturally produces a protective oxide that regenerates when scratched, which coats the outside. This oxide layer is highly corrosion-resistant, resulting in maintenance costs, and produces an aesthetic metal face without rust stains. When the material costs of the bridge are competitive, transportation costs, installation costs, maintenance costs, longevity, and recycling costs aluminum ramp aluminum has a much lower total cost of ownership than steel bridges.