Omaha-based HDR is expanding its team of urban and regional planners by acquiring Calthorpe Associates, based in Berkeley, Calif. The firm will operate as HDR|Calthorpe. Calthorpe has been an international leader in smart growth and is a founding partner in the Congress for the New Urbanism, according to a release. Calthorpe founder and principal Peter Calthorpe will join HDR as a senior vice president. Joseph Scanga will join HDR as a vice president. HDR has an office in Des Moines’ East Village.