PITTSBURGH — A $523 million light-rail tunnel under the Allegheny River in Pittsburgh is set to open as scheduled March 25.

The Port Authority of Allegheny County’s 1.2-mile light rail extension stops near PNC Park, Heinz Field and the Rivers Casino. The light-rail system serves downtown and primarily the city’s South Hills suburbs.

A report Monday said a test train took less than two minutes to make the trip from downtown to the station nearest PNC Park.

The Steelers, the casino, Alco Parking — which runs several lots near the stadiums — and the Pittsburgh Stadium Authority are paying for passengers to use the extension for free for three years.