Born in Conklingville, New York, Holleran received his early education at public schools in upstate New York, before graduating with a Bachelor of Engineering degree in 1906 from Union College in Schenectady, New York. His first engineering job was with the Owego Bridge Company in Owego, New York, though he was later appointed the assistant engineer of the Board of Water Supply in New York City, where worked on the construction of the Catskill Aqueduct. Holleran remained in this position for eight years until he was appointed assistant engineer with the Bronx Parkway Commission in 1914. From that position, he was promoted to principal assistant engineer and then deputy chief engineer. Holleran, along with landscape architect Gilmore Clarke and engineer Jay Downer, supervised the construction of the Bronx River Parkway, completed in 1925. During this time, Holleran was also appointed to the position of deputy chief engineer of the Westchester County Park Commission, and between 1923 and 1932 worked with Downer, Clarke, and Hermann Merkel on the design and construction of the 30-mile southern section of the Taconic State Parkway, known as the Bronx Parkway Extension.
Holleran wrote numerous articles, including “The Bronx River Parkway Drive,” published in Good Roads (1922), and “Economical Use of Concrete in Bridge Construction,” published in Engineering and Contracting (1923). He was a member of the American Society of Civil Engineers, the American Road Builders Association, the American Society for Testing Materials, and the American Institute of Park Executives. Holleran died at the age of 70.