The Carlton Bridge is a railroad vertical-lift bridge which carries one rail line over the Kennebec River between Bath and Woolwich, Maine. It was completed in 1927. Until August 1, 2000, it also carried two lanes of U.S. Route 1 (US 1) on its upper deck, after which the highway was transferred to the adjoining Sagadahoc Bridge and the road connection severed. The majority of the road deck remains but may be removed in the future. It is the last downstream fixed crossing of the Kennebec.
With the removal of US 1 from the bridge, its primary traffic is freight trains operated by the Maine Eastern Railroad that are bound for manufacturers in Thomaston, of which several pass over the bridge per week. It has also carried passenger excursion trains to Rockland, though the Maine Department of Transportation's leasing the line to another company will likely mean the end of passenger service after 2015.
The 88-year-old bridge failed an inspection in the fall of 2013, resulting in its closure from February 23 to 25, 2014, for an in-depth inspection and load test. The in-depth inspection found that steel has been rusting away from the bridge and at least one beam needs repair. Despite the deficiencies found, MDOT has stated that the problems do not currently impair the running of trains across the bridge. No restrictions have been placed on the use of the bridge, though MDOT requests that the Maine Eastern Railroad notify it of the days trains pass over the bridge. No decisions have yet been made about how to address the deficiencies, though options include repainting the bridge, removing the remaining road deck, or even its closure.
- "After losing state lease to competitor, railroad company leaving Maine". Bangor Daily News. September 4, 2015.
- "Rail officials say rust will force decision on 88-year-old Bath bridge". Bangor Daily News. March 23, 2015. Retrieved September 8, 2015.