transferred to Pan Am Southern, a 50-50 joint venture of Pan Am Railways and Norfolk Southern Railway. Freight trains through the tunnel are operated by Springfield Terminal Railway, the train-operating subsidiary of Pan Am Railways. The route is currently used to transport freight but has seen passenger excursion trains on rare occasions. It was converted to a single track in 1957. Clearances were increased in 1997 and 2007, the former by lowering the track, the latter by grinding 15 inches (38 cm) off the roof, allowing trailer on flat car (TOFC) and tri-level automobile carriers to pass. In March 2012, the Federal Railroad Administration awarded a $2 million grant to the Massachusetts Department of Transportation for preliminary engineering on further increasing clearance in the tunnel to allow double stack container trains to use the tunnel. As of 2019, MassDOT, with FRA support, has surveyed the Patriot Corridor, including the Hoosac Tunnel, and identified 19 improvement projects needed to achieve double-stack clearance. MassDOT is preparing needed environmental reviews. As of 2023, approximately five freight trains per day operate through the tunnel. On February 12, 2020, the tunnel collapsed approximately from the West Portal. Subsequent collapses occurred in the following days. Crews were able to repair the tunnel. Freight traffic was detoured over the New England Central Railroad and Vermont Railway while Intermodal traffic was detoured via CSX during the closure. The tunnel reopened on April 4, 2020, after a two-month closure. CSX acquisition of Pan Am Railways On November 30, 2020, an agreement was announced for CSX Corporation (parent company for CSX Transportation) to acquire Pan Am Systems. With the sale, the intermodal traffic between Mechanicville and Ayer will be re-routed over the B&A to Worcester, MA. From there the traffic will come up the Worcester main and into Ayer Yard. On April 14, 2022, The Surface Transportation Board fully accepted the purchase by CSX Transportation of Pan Am Railways and 50% of Pan Am Southern. The combination of several trackage rights agreements in the approved plan will create a new route allowing Norfolk Southern to move double-stack intermodal trains and automobile trains from Voorheesville, New York to Ayer, Massachusetts (the Southern Route). The Hoosic Tunnel on the Pan Am Southern (the Northern Route), used by NS prior to this agreement, is too low for double-stack trains. Berkshire & Eastern Railroad (B&E), a wholly owned subsidiary of Genesee & Wyoming (G&W),