Are there any sensitivity analysis results available from the NBIAS model?
Yes. NBIAS applies a swell factor to maintenance, repair, and rehabilitation (MR&R) needs to account for the way in which such projects are implemented in practice. When State and local governments repair or rehabilitate deficient components of bridges, they typically try to raise the standards of other components that might not yet be deficient. In other words, MR&R actions cannot be viewed in isolation, and a swell factor is applied for these related improvements. This logic was also applied to the NBIAS results in the 1999 C&P report. For this report, a swell factor of 1.25 was assumed. Assuming an alternate value of 1.12 reduces the Cost to Improve Highways and Bridges by 10.5 percent and reduces the Cost to Maintain Highways and Bridges by 5.7 percent. A 1.0 swell factor reduces the Cost to Improve Highways and Bridges by 20.5 percent and reduces the Cost to Maintain Highways and Bridges by 15.8 percent. NBIAS is currently being improved so that individual bridge analysis can be d
