Great question. That can and has been done. The problem is it's enormously expensive as you're dealing with competing optimizations. Railroads can't go "anywhe

Great question. That can and has been done. The problem is it's enormously expensive as you're dealing with competing optimizations. Railroads can't go "anywhere", generally you need very shallow grades and the right structure underneath the tracks. Unfortunately the soil, rock layers, fault lines (think small fractures that water travels along, not san andres), drainage patterns, and many more factors contribute to environmental safety beneath said lines. So your rail would likely not be able to take the most efficient or straight path for rail. This isn't a problem for something like the XL pipeline, which had sealed clay basins planned in worrysome areas. Train wrecks are also catastrophic, so while catch basins work pretty dang well, they can damaged easily in events like that. So you end up having to make compromises somewhere: efficient trains vs environmental safety. Pipelines have similar issues, but they're not dealing with thundering transient loads, and modern pipelines are very safe compared to their 50 year old counterparts, in the same way US nuclear reactors are far safer than RMBK reactors. Tracks that can "haul anything" certain could be built, but at a larger cost than general freight rail.