PORTSMOUTH — The New Hampshire Department of Transportation announced that work associated with the replacement of the Islington Street Bridge over the Route 1 Bypass is complete, four months ahead of the contract completion date.

The new bridge opened to vehicle and pedestrian traffic in the late afternoon on Tuesday, May 12. Variable message boards and detour signing deployed during the closure will be removed. Resurfacing work on the Route 1 Bypass below the bridge will take place within the next two weeks.

The reopening of the Islington Street Bridge follows the replacement of the Middle Street Bridge over the bypass, leaving the Maplewood Avenue Bridge as being the last of the closed overpasses.

The Sagamore Creek Bridge was also replaced during this time period and it reopened in December.

E.D. Swett, Inc., of Concord is the prime contractor for the $4.3 million Islington Street Bridge replacement project, which also included the replacement of the Middle Road Bridge over the Route 1 Bypass. The Middle Street replacement was finished in 2014, about seven months ahead of schedule.

Replacement of the Islington Street Bridge is part of an overall project to upgrade the bypass overpasses as well as the Route 1 and Route 1 Bypass interchange. Public Works Director Peter Rice said the Maplewood Avenue Bridge will reopen in October. That bridge was closed in July 2014.

Completion of the Maplewood Avenue Bridge will draw to a close an unprecedented era of bridge infrastructure projects in the city, allowing for a normalizing of traffic patterns in Portsmouth. However, the Sarah Mildred Long Bridge is scheduled to close for up to 10 months beginning in early 2017 as part of that replacement project.