The second approach involved the exploration of the relationships between bridge paint condition data that has been screened to remove the effects of agency response and depositional environment. Data from Ohio and New York were obtained.
The county level data for Ohio was for 1992 and no correlations to deposition data from RADAM and NTN could be identified. The New York state data consisted of bridges that had not been repainted in the period 1986 to 1993. The data was correlated with acid deposition environments identified as low, medium and high. Surprisingly, areas with high deposition were associated with bridges in the best condition and showing the slowest deterioration rates and areas with low acid deposition were associated with bridges in the worst condition and showing the highest degradation rates.
While previous studies and experimental work have not necessarily involved the type of paint systems used on bridges or the typical exposure levels, additional experimental work may provide some interesting insights. However this project suggests that the inherent variability in the condition rating process, the number of variables that are not observed and the local variations in depositional environments are likely to exceed the variation attributable to changes in emission levels nationally.