The Germans have the best applied data -- the Hannover-Hamburg line of the ICE [link|http://www.o-keating.com/hsr/icecrash.htm|sufferd a derailment] in a middle car of a multi-car train, at 200kph (about 125 mph). Top cruising speed is nearer 280 kph, or 174 mph. The derailment itself wasn't quite so bad as the subsequent collision with an overpass, with fatal consequences for the track crew on the scene as well. The cause is commonly attributed to be a broken wheel (not detailed in the article above). The accident killed 70. This is the line my cousin and his fiance take regularly.


A French TGV derailed at 182 mph (294 kph) from axle failure, resulting in minor injuries.

As the old saw goes, it's not speed that kills, but the sudden deceleration at the end. A derailment in which rolling stock slides to a halt in open country is going to have a significantly different profile than a collision with other rolling stock, fixed structures, or incidents involving bridges, tunnels, or significant slopes (eg: mountainous regions).

Trains are substantially more structurally robust than airplanes. Though accelerating mass costs energy, trains aren't tasked with lifting it to altitude. Likewise, a small explosion on an airplane can result in a loss of pressure containment, which very frequently leads to major structural loss (though not always: loss of windows, and even hull sections, has occured on modern jetliners, without total loss of craft, passengers, or control). An aircraft has to contend with both horizontal decelleration and vertical impact. As the old drunk's saying goes, it's hard to fall off the floor.

The track record (so to speak) of high speed rail is quite good -- the German accident was the first in seven years. The disadvantage is a largely accessible infrastructure (the right of way), should a saboteur chose to lay waste to it. France, Germany, and Japan have a substantial and good history with the technology. England, by contrast, has a problem (and disaster) prone rail system widely seen as a national disgrace.

In the US, high-speed corridors with trains travelling up to 125 MPH exist, largely in the Boston-Washington area. It's proven popular both before and since Sept 11. Other projects are under exploration, largely SF-LA, Dallas-Houston, and possibly extending from Chicago, though these are largely moribund. Distances and population densities in the US make HSR a difficult prospect, though for transits of up to 500 miles, it should prove competitive with air travel.