This is
the BBC» 's static news item on his accident, Its content is mostly as in the rolling news item, and it is still dated yesterday; I would point to this paragraph:
Local outlet The Nation reported that the incident occurred while the crane was lifting a large concrete section which dropped on to the train, causing several coaches to derail.
There is also this picture, credited to Reuters, which strongly suggests a major failure of the launch girder system itself. The perspective is confusing -
The Times had a better view, I think from Getty, which I can't find anywhere on-line.
[Image from here is not available to guests] You may remember how such a system works, from the one used on the Colne Valley Viaduct (aka Dominique). The girder must rest on two supports at all times, and it moves forwards along the viaduct either by a support crawling along the now-built viaduct, or using a third support.
What I see in the picture suggests something along these lines: the forward support has collapsed, the girder has fallen onto a pier ahead of where segments are being added, and it has buckled. The moving crane that carries the segments was operating at the time, and could not sustain the shock as the girder landed; part of that crane, and perhaps the segment, fell off. That forward support can't be seen, so most of it may also have fallen onto the train.
Note that this is not unprecedented - another launch girder operating in Thailand, this one building a road viaduct (and painted blue) collapsed in January 2024.
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