HANNIBAL â It will be over a year before the replacement of the Mo. 79 viaduct in Hannibal will begin. The Missouri Department of Transportation has already begun the process of notifying the community about what the project will entail. âWhen we started this (informational) process about a year ago we actually had some meetings with first responders and different groups because we know with a replacement project like this there will be an impact so we have started working on that,â said Brian Untiedt, central area engineer for MoDOTâs Northeast District, during the July 6 meeting of the Hannibal City Council at city hall.