Commuters on the Massachusetts Turnpike are in for a real treat. As they muscle their way in to Boston, they will be greeted each day with changing digital images projected from a 30 ft tall screen located at the terminus of a 480 ft long bridge-like structure dubbed “the beam”. The beam is part of the WGBH Public Television’s new Headquarters building in Brighton, Massachusetts designed by New York-based Polshek Partnership Architects.