The state plans to replace a heavily traveled bridge that carries Interstate 295 traffic over Veranda Street just north of downtown Portland. The project is still at least two years away, but officials are already planning for the disruption of traffic in and around Portland, including a multiday closure of the highway so the replacement bridge can be moved into place. State transportation officials will introduce their preliminary designs for the $12.4 million bridge replacement project Tuesday at 6 p.m.