The General Motors Arlington Assembly Plant, which is undergoing a $1.4 billion expansion to meet the global demand of their full-size, sports utility vehicles, celebrated a major milestone Friday.During Friday’s ceremony, construction teams, plant employees and GMs leadership took turns signing the final steel beam required for the paint shop expansion. The crowd clapped and cheered as the autographed beam was hoisted into place at the top of the massive facility, which is set to open along with other plant expansion projects in 2018.“If you saw the last beam being installed, they make it look easy. But this was a tremendous task. They did it on time, in a safe way and especially high quality,” said Juan Carlos “J.C.” Jimenez, plant manager. “This is a building that is going to stay there for a long time.”GM is one of the biggest employers in Arlington and North Texas and is a key part of the City’s economic foundation. GM Arlington Assembly currently employees more than 4,000 people.