At the far end of civilization, America’s immense and untamed northern frontier only accepts the hardiest of adventurers. The 49th state’s 663,000 square miles of wilderness are intimidating to travelers, an unfathomable expanse of snow-drenched mountains and impenetrable forests. Travelers on foot face ferocious wildlife and challenging trails, drivers are impeded by the limited roads, and cruisers miss the astonishing Alaskan interior. The natural solution, it would seem, is train travel…