(AREA) -- Despite this winter's very cold and snowy weather, work on the 140-mile Thumb Loop high-voltage transmission project is on schedule as it enters its next-to-last year of construction. ITC Transmission says work has started on the final line segment, which is about 56 miles from the Rapson substation near Bad Axe, south through Sanilac County to the Greenwood substation in St. Clair County. Crews are drilling and pouring foundations in Huron County and poles are being hauled to their locations along the line right-of-way. This section includes the new Banner substation near Sandusky. Line work in Sanilac County will get underway in the next few weeks. The entire Thumb Loop project is expected to be complete and in service on schedule in 2015. The line will tie Thumb wind farms into the state's electrical grid. The Thumb Loop runs from Tuscola County through Huron and Sanilac counties and ends in St. Clair County. The St. Clair County substation Fitz in Wales Township should be finished this summer.