When traffic travels beneath a steel overpass or through a steel truss or similar structure, an area of the steel above and often beside the traffic is bathed in water from the roadway. This water is deposited on the steel surfaces. Figure 6.13 shows the effect of roadway splash on coated railings. Splash from automobiles and trucks can travel vertically as high as about 20 ft and horizontally 10 ft or more. Painted steel surfaces within that envelope will be in an environmental Zone 2A, 2B, 2C, or 2D (as previously described) and perhaps in a zone requiring special treatment with zinc spray metalizing when possible, galvanizing any steel that is replaced and any steel that can be removed, galvanized, and returned to service.