AUGUSTA, Maine — Central Maine Power Co. says it has reached a milestone in its project to build a 440-mile transmission line through the southern half of Maine.

CMP workers this week set the project’s 1,000th utility pole along a corridor in the town of Leeds. In all, the entire project will require about 5,000 new poles.

The poles are part of CMP’s new 345,000-volt transmission line that will stretch from Orrington to Eliot, doubling the capacity of the grid’s backbone.

CMP says the $1.4 billion project is the largest construction job ever undertaken in Maine. Completion is expected in 2015.