In addition to the above-mentioned studies, several states have independently evaluated weathering steel bridges in their inventory and these include: Louisiana, Idaho, and Texas. Louisiana has cited corrosion problems in some of its weathering steel bridges, particularly along the gulf coast, due to airborne salts (Raman and Naszrazadani 1989). The primary locations where excessive corrosion was found to develop include areas: (1) near piers,
(2) where wildlife (particularly birds) sheltered,
(3) where condensed water collected and pooled, and
(4) at locations with accumulated debris.
In their research, Raman and Naszrazadani cite instances in which the application of a tannic acid solution was found to stabilize the corrosion rate (1989). However, it is not yet known if this would be acceptable as a general practice. In 1995, the Idaho Transportation Department inspected 12 of its 40 unpainted weathering steel bridges (Jobes 1996). A protective oxide coating was observed on all 12 of these bridges and the continued use of weathering steel bridges in appropriate environments was recommended. The Texas Department of Transportation has also recently completed a study focusing on the performance of weathering steel used in bridges in that state (McDad et al. 2000). During this project, 40 weathering steel bridges throughout the state were independently inspected. The bridges were selected to be representative of five different site conditions: coastal, industrial, urban, suburban, and rural. The inspections revealed similar findings for all of the bridges except for those in coastal areas. In particular, the interior surfaces of bridges in coastal areas had larger flakes than the other bridges inspected; the exterior surfaces of the coastal bridges were similar to those of the other bridges evaluated. McDad et al. (2000) concluded that weathering steel bridges were generally a cost effective alternative for use in Texas. The situations in which they did not recommend its use were:
(1) in the presence of corrosive industrial or chemical pollution,
(2) in locations of heavy salt-water spray or salt-laden fog,
(3) uses in conjunction with timber decking, and
(4) in depressed roadway conditions over roadways on which deicing salt is used.