HARRISBURG — A new Pennsylvania Department of Transportation study released Friday showed that a high-speed passenger rail connection between Harrisburg and Pittsburgh could cost anywhere from $1.5 billion to $38 billion.

The study’s release began a six-week period during which the agency will accept public comments on it. The study began in 2011 with the help of federal money.

While the state receives federal money for mass transit services, there is no money that has been identified yet to fund what is called the Keystone West rail line, a PennDOT spokesman said Friday.

It notes that there currently is only one, inconvenient passenger rail service — Amtrak’s once-a-day Pennsylvanian service takes 5½ hours — and a lack of intermodal connections at the existing stations on the 250-mile project length and no connecting service to State College, an area of high commuter population.

High-speed service could cut travel time by an hour to 4½ hours, it said.

The $1.5 billion project would involve modifying curves using the existing path while maintaining stops in Greensburg, Latrobe, Johnstown, Altoona, Tyrone, Huntingdon and Lewistown, and adding a rail or bus spur to State College. A $10 billion alternative would use the same path, plus more improvements to add speed, while a $13 billion alternative would include the addition of a continuous third track.

Unlike the Keystone East line between Harrisburg and Philadelphia, the Keystone West line is not electrified, requiring diesel power for both freight and passenger trains, the study said.

The route is heavily used for freight rail operating at varying speeds, which limits the ability to schedule additional passenger service. Differences in speeds pose a substantial operating challenge.