merged into Penn Central Transportation in 1968. Penn Central went bankrupt in 1970 and in 1976 its suburban trains were taken over by Conrail, then by NJ Transit in 1983. Penn Central long-distance service (including part of today's Northeast Corridor and Empire Corridor) had been taken over by Amtrak in 1971. Amtrak took control of the North River Tunnels in 1976, and NJ Transit started running trains through the tunnels under contract with Amtrak. Operation Portals The west portals are in North Bergen, at the west edge of the New Jersey Palisades near the east end of Route 3 at U.S. Route 1/9 (). They run beneath North Bergen, Union City, and Weehawken, to the east portals at the east edge of 10th Avenue at 32nd Street in Manhattan. When the top of the Weehawken Shaft was covered is a mystery; the two tracks may have remained open to the sky until catenary was added circa 1932. The two portals on the Manhattan side fanned out into 21 tracks just east of 10th Avenue, serving the platforms at Penn Station. 450 West 33rd Street (now Five Manhattan West), on the east side of 10th Avenue, was built above the east portals in 1969. Except for a curve west of the west end of Pier 72 that totals just under a degree, the two tracks are straight (in plan view). They are apart from west of 11th Avenue to the Bergen Hill portals. The third rail now ends just west of the Bergen Hill portals. Capacity and useful life The North River Tunnels allow a maximum of 24 crossings per hour each way. Since 2003, the tunnels have operated near capacity during peak hours. The number of NJ Transit weekday trains through the North River Tunnels increased from 147 in 1976 to 438 in 2010. Trains ordinarily travel west (to New Jersey) through the north tube and east through the south. During the busiest hour of morning rush, about 24 trains are scheduled through the south tube, and the same number travel through the north tube in the afternoon. The tubes run parallel to each other underneath the river; their centers are separated by . The two tracks fan out to 21 tracks just west of Penn Station. Expansion and restoration proposals Beginning in the 1990s several proposals were developed to build additional tunnels under the Hudson, both to add capacity