• Mack Trucks, Lehigh Valley, Pa., announced Dennis Slagle will succeed Paul Vickner as the company's president and CEO.

  • John Hadfield, executive director of the Southeastern Public Service Association, Chesapeake, Va., will retire, effective Aug. 1.

  • Weston & Sampson, Peabody, Mass., introduced Michael F. Clark as regional manager of Florida operations.