In its present form yes, additionally widening the existing viaduct over Gateway Field would be politically contentious, so would be expanding the Waldo Tunnel and while you could double track Long Dock Tunnel you would succumb to clearance limits which would prohibit certain freight cars from going through, at that point you would have to do some serious engineering/reconstruction work to accommodate those cars while double tracking the tunnel. Its a lot of money for comparatively little benefit. The construction of the Waverly Loop, which was completed this year, bypasses this problem entirely. Double stack container trains can leave Port Jersey go over the Newark Bay Bridge and than turn onto the Passaic & Harsimus Branch to continue north. Here is the slideshow from the NJTPA's Freight Initiatives Meeting which included reps from the Port Authority and Conrail. Its provides details on current projects, future projects and hard numbers for the ExpressRail facilities.