Though that the train was travelling at 80mph in a 30mph zone is ample reason to posit that the train's speed was the cause of the accident, that being so is not a foregone conclusion. There are plenty of waterways, air routes, road and rail sections whereat "posted" speed limits are a function not of what the road, rail, water or air can sustain but rather because of environmental and/or situational factors having nothing to do with the medium by which vehicles are transported. For instance, on roads, congestion and the potential presence of careless-enough road-crossers is often enough a reason for a relatively low speed limit. Another reason for comparatively low speed limits in places is that freight trains may safe to travel on that track corridor at 30mph and passenger trains safe at 80mph, but the speed limit is yet set at 30mph. Yet another reason for "posted" speed limits being comparatively low can have to do with what's far ahead along the transitway or what one has just passed. We routinely observe that sort of thing when entering and exiting cities and towns and in many cases the the lower speed limit has nothing to do with whether the road/rail can handle vehicles travelling at faster speeds than are stipulated. Accordingly, absent some obstruction on the track or weakness in the trestle (bridge?), it's entirely possible that the track is more than capable of handling a passenger train (as compared to a freight train) travelling at 80mph. Does that mean the train's speed isn't the cause of the accident? No. It means that concluding that speed was the cause constitutes jumping to conclusions. For the train's speed of travel to have been the cause, the train would have had to have been travelling faster than the track -- both its structure and layout -- could sustain without trains routinely jumping the track. I doubt that anyone thinks infrastructure upgrades, refurbishments and new installations are not overdue. Too, I cannot imagine many people oppose seeing their tax dollars used to that end. I suspect there is, however, a whole lot of disagreement about the prioritization of the upgrades, refurbishments and new installations. To be sure, for example, the airline industry wants to see nothing resembling major upgrades in rail infrastructure. Indeed, the airline industry would, I suspect, become all but apoplectic were we to implement a national maglev rail infrastructure for it would,in all likelihood effect the end of regional commercial passenger airline travel.  (See also: Japan's maglev train goes 374 mph, sets world record - CNN Video) Note: Were regional airline flights supplanted by regional train travel, I, for one wouldn't miss traveling by regional passenger jet. No planes are less comfortable and less safe to be on and passengers get no greater airport or other conveniences/advantages for travelling on the damn things. There're a bunch of reasons people take the Acela between between Boston and NYC and D.C. and NYC. Maglev speed trains between those cities would result in nobody flying between them on commercial passenger planes. I doubt many folks would even take charter flights for those trips.