Repainting of bridges over highways or railroads may necessitate use of protective covers, or require traffic lanes to be diverted or work interrupted during passage of trains, while existing paint is removed and new paint applied. These factors all favor use of a bridge material or protection system that does not require maintenance reapplication of a coating. (See Art. 4.13.)
Removal of Existing Paint. Complete removal of the existing paint on a bridge that is to be recoated with a paint system that requires it can be extremely expensive, particularly if the existing paint contains lead. Lead-based paints were used extensively in the past because they provided good protection. Because of the health issue involved, portions of bridges where lead-based paints are being removed are often required to be completely enclosed, and the paint particles contained and properly disposed of, often at great cost. Severe monetary penalties can be imposed if violations occur. (See Art. 1.4.)
Repainting. Maintenance paint should be applied with the same care as paint on new bridges, but it must be applied in a more difficult environment. Painting must be done under acceptable atmospheric and environmental conditions, particularly in regard to temperature, humidity, wind, and absence of dirt. Overspray onto vehicles and other objects must be prevented. Some painting contractors are consciously careless about this, preferring to take their chances and let their insurance company pay claims, rather than taking necessary precautions. This results in bad public relations between travelers and the owner.
Because of the cost associated with complete removal of existing paint, paint systems that do not require complete removal, but only removal of loose paint and minimal preparation of sound paint and exposed steel, are much desired. Some such systems are on the market. While longevity can be projected by accelerated testing, only realtime exposure will truly prove their worth.
Inspection. Thorough inspection during repainting contracts is essential to satisfactory performance. Painting contractors often work during off-hours, and so the owner’s inspectors should be prepared to work those same hours. Inspectors should follow closely behind the painters. On high bridges, the use of inspection devices such as high lifts, Reach-Alls, Snoopers, or cherry pickers, which permit inspectors to reach areas otherwise not readily accessible, will keep the painters on their toes just through awareness of their availability to the inspector.
