The Arizona Department of Transportation has completed the first draft of an environmental assessment examining the proposed route of a passenger rail line between Tucson and Phoenix.
The document is an early step in a process that could take years to complete even before construction is to start.
The proposed rail line would run from Tucson International Airport to Phoenix Sky Harbor International Airport, with extensions to Goodyear and Surprise in the Phoenix area.
The ADOT report looks at the potential environmental impact, the need for passenger rail, the effects on transportation, and analyzes cost and other aspects of building the railway.
The study notes the potential costs of construction for the rail line range from $4.5 billion to $7.5 billion.
Annual operations and maintenance costs also vary from $66.8 million to $85.9 million.
The per-mile operating costs varied from $557,668 to $669,240.
ADOT notes the need for transportation alternatives between Tucson and Phoenix continues to increase as the population grows.
The report estimates Interstate 10 travel between Tucson and Phoenix will take 26 percent more time by 2035 and 59 percent more by 2050. That even assumes I-10 is widened to 10 lanes.
ADOT has scheduled three public hearings on the report. The sole Tucson hearing is set for Sept. 16. It will be from 5:30 to 7 p.m. at the Tucson Convention Center Leo Rich Theater, 260 S. Church Ave.
