Far as I know the DPW 'trolley barn' on Hackesack St. near the Erie underpass was for the Newark to Hackensack trolley line. The HR&P ran East/West on what is now Paterson Plank Rd and crossed the N/S line at Hackensack Ave. Maybe they both used one car barn?
If you take the inset pic on the "Lines of the Paterson, Passaic, & Rutherford Electric R'y and the Jersey City, Hoboken & Rutherford Electric R'y, and the Paterson Central Electric Ry., Charles A. Johnson, president, James A. Morrisse, vice president." map from the American Memory series, and flip it horizontally, it would sure fit the location of the carbarn vis a vis the Erie. I wonder when the Hackensack underpass was built?
Bring back the Slumbercoaches!!