Train collision in Bavaria

[kvp]

It seems the signaller managed to do what i described as highly unlikely but not with a clear green but a call signal instead. They are not checked by the route control circuits as they are only meant for shunting movements into occupied tracks, usually station switchers attaching/detaching a few cars using the mainline as a lead track, with all entry and exit signals set to stop. They can be used to let a train into an occupied block (this has happened in hungary too in the past) in case of a signal system error, but if continous signalling is in use, the trains will see each other and stop regardless of signaller action. With the pzb90 system, once the train cleared the exit signal (possibly by pressing the pzb cancel button after the emitter), it was only possible to stop it through the train radio system (if there was any) as the next pzb90 stop emitter is at the entry or block signal on the opposite end of the block. Usually these signals should not be allowed to be operated without locking the whole line to stop and locking should not be allowed while any open line blocks have an active occupancy unless a mechanically sealed block detection override switch is activated, but it looks like these safeties were either not used or were broken by the signaller. (not present is more likely, but i can't say much about likelyness) Sadly if both trains were keeping their assigned speed restrictions (100 and 40 km/h), that's still a relative collision speed of 140 km/h.

[spacecadet]

I really question why NTSB takes so long.  Are they really working all day for those 365 days (minus weekends and holidays)?  Just what will they discover in those 11 months beyond the first?  To the extent that whatever is learned could help prevent future problems, you'd think they would want to reach a conclusion much more quickly.

The NTSB releases recommendations as they have the info they need to do so. After aircraft accidents, for example, you will often see several airworthiness directives come out of the FAA very soon after an accident, which are based on preliminary conclusions from the NTSB.

 

The NTSB actually describes its process here: http://www.ntsb.gov/investigations/process/pages/default.aspx

 

A lot of an investigation involves interdependencies. For example, a metallurgical examination can't even start until all the relevant parts are collected, identified and cataloged. That alone can take weeks or even months.

 

Often, though, an investigation will be complete within a matter of months, but writing the actual report is an arduous process. Every word is pored over to ensure accuracy and a lack of bias. And these reports are hundreds of pages long, and they're hundreds of pages of highly detailed technical material from various disciplines that no single person can really know enough about to report on himself. So just writing that report involves a lot of back and forth between various people, meetings to make sure everyone understands what's being put in a particular section, then of course the actual writing, more meetings and back and forth, further editing, etc.

 

Think about how long it takes to write an average novel. Now imagine how long it takes to write a novel where one chapter is about the metallurgical properties of fluted steel as it pertains to current FRA regulations. Now imagine you're not really a metallurgist. That's why they hired you to write the report instead of analyzing the metal.

 

Those are some of the reasons why it takes so long. And that's not getting into things like public hearings, which some investigations also have. Those take a while to prepare for and then digest too. But one thing about them is they allow you to see the massive amounts of evidence the NTSB often has to sift through. Often it's not that they don't have enough evidence, but that they have so much that it just takes a long time to look at everything. And they may not have that *one* piece of evidence that they need in that haystack.

 

Lastly, sometimes I think people have the impression that the NTSB has like 200 people investigating an accident... usually it's more like six. Even for big accidents.

Edited February 18, 2016 by spacecadet

[cteno4]

very well said! thanks

 

jeff