The man was waiting at the crosswalk at the county Department of Social Services building at 797 Broadway on Wednesday when a van came to a stop in the westbound lane, authorities said.
A garbage truck then struck the van from behind before striking a crosswalk sign and utility pole, which fell and struck the pedestrian, city police Sgt. Nick Mannix said.
The injured man was taken to Albany Medical Center for a head laceration, police said.
The incident remained under investigation by city police and the state Department of Transportation, which will impound the vehicle.
The driver of the garbage truck, which is operated by Altamont-based Pollard Disposal Service, has been cooperative, said Mannix, who expects the driver will be ticketed.
The van sustained significant back-end damage.
This developing story will be updated as more information becomes available.