The Pennsylvania Trolley Museum in Washington, Pa., has been a destination for trolley fans for decades. But now, the museum is embarking on construction of an imaginative expansion project for which over $14 million has been raised. Ground broke Thursday for the building of a new 21,000-square-foot Welcome and Education Center. Based on what museum officials are saying about the new center, the plans call for an even more immersive experience for trolley buffs. But there also are practical reasons for the expansion. “We have a small visitor’s center, but it’s only about 2,000 square feet, so it’s pretty small,” said Scott Becker, Pennsylvania Trolley Museum executive director. “Of course we have the trolley barns. But we’ve run out of room, especially when we have special events.”