Why do all those bridges need to be removed and replaced? Are they old? Falling apart? Too narrow? Why?

Most need to be replaced due to poor conditions. The West Interchange Road and Corn Crib Lane overpasses have piers or other factors that will conflict with the proposed US 1 improvement, such as removing the 16-foot-wide separation between the US 1 freeway and the service roads and necessitate their replacement. Additionally, all three of the overpasses do not meet vertical clearance requirements and have been struck by trucks in the past.