Transwestern Development Co. is planning to build The Exchange, a 300,000-square-foot office building in the CityLine development in Richardson. The six-story Class A office property is slated to be a joint venture between TDC and BC Station Partners. Construction will commence once a tenant is secured for the building. The Exchange will be located near the southeast corner of the intersection of North Central Expressway and President George Bush Highway. 713-270-7700.