They certainly can, but to build two you first build one. And if that one is not profitable, why would adding another one make it so? You could say that building 2 parallel tracks is not significantly more expensive than building one, and when you have the 2 you need less slack in the system, so you can have closer to 100% utilization rate. Yes, you could gain some economies of scale, but the fundamental problem remains: if you cross the canal, you just float on water; if you decide to use this alternative, you need to unload the ship, load 20 trains, run the trains for 300 km, unload them and load them on another ship. To be competitive with the canal, you need to do this for about $200k. The $200k should cover the operating costs (fuel, labor, equipment depreciation), the maintenance costs, the insurance costs, the capital costs and hopefully should include some profit.
