On the other hand, if the new Gateway tunnel is built, it would allow an additional 24 trains per hour to travel under the Hudson River, supplementing the 24 trains per hour that could use the existing North River tubes.
This alternative scenario suggests that if the Gateway tunnel project proceeds, it will allow for an increased number of trains to pass under the Hudson River, in addition to the current 24 trains per hour that can use the existing North River tunnels.