Passenger trains did tolerate harsh winter weather into the 50's and 60's, but things have changed in many ways since then. First, there are no longer an abundance of wayside stations to stop at obtain help, many places along these long distance runs are a long way from anything as not only have the stations closed, many of the small rural towns have also dried up. Second, the level of liability is greater now, today, if anything goes wrong, you are assured of at least one lawsuit as a result, no one today can be expected to go with the flow or tolerate adverse conditions without some sort of compensation. Thirdly, like it or not, the P-40 and P-42 engines Amtrak uses these days have never been a reliable winter engine for a variety of reasons. In fact, BNSF requires at least three engines on the Empire Builder during the winter months for no other reason to maintain hotel power for the train should something happen. Host railroads frequently stop Amtrak when the winter going gets tough so that they don't have to deal with an Amtrak train full of people with dead or near dead locomotives.