Diesel-electric locomotive crashworthiness

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Diesel-electric locomotive crashworthiness
Posted by VOLKER LANDWEHR on Monday, August 07, 2017 3:48 AM

I have a question about the crashworthiness of Diesel locomotives.

I found that the earliest requirements were PRR passenger cars with a buff load of 200.000 lbs in 1906 followed by RPO cars with 400,000lbs in 1912. It was later doubled to 800,000 lbs.

in 1939 the AAR made the 800,000 lbs a Recommended Practice for passenger cars and a Standard 1949 (S-034: Specifications for the Construction of new Passenger Eqipment Cars).

In 1956 it got mandatory for MU- units.

Locomotives are never mentioned. Rules for locomotives that I know were first published in 1989 with AAR's S-580. Later came the FRA and APTA rules.

Adopted the locomotive manufacturers the above buff loads volontarily? Or were there no crashworthiness measures before 1989?
Regards, Volker

RME
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Posted by RME on Monday, August 07, 2017 4:59 AM

Crashworthiness in locomotives is a radically different thing from buff and draft strength in things like RPO cars, which run in-train and aren't expected to absorb primary collision impact as a locomotive cab is.  If I remember correctly, the 800,000# standard was specifically imposed on RPOs first, as they involved Government personnel -- I don't have my copy of the 1940 version of the AAR standard handy, but I remember it specifically mentioning this.

To an extent, iirc, the buff standard was extended to cab units because early cab-unit design, particularly EMD F units, did not have particularly high effective buff strength in the carbody design and enginemen could be expected to be in the 'machine spaces' at the time of an accident.  Hood units have less of an issue with this.

All the recent work I have seen with locomotive crew safety has involved armoring and reconfiguring the cab and preventing collisions from overrunning the occupied areas of the cab.  There is less concern with buckling the locomotive frame than with keeping the engine and alternator from becoming too friendly with the cab rear bulkhead, and it can be interesting to see the ways in which modern designs handle that.

As a rudimentary entry point to this subject, here is the FRA page on "Locomotive Occupant Safety".  This has a link to the eLibrary which has more detailed results for some of the programs and practices.

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Posted by VOLKER LANDWEHR on Monday, August 07, 2017 9:27 AM

In today's regulations buff loads are one part in Crashworthiness design.

The AAR's 1989 S-580 contained collision posts, anticlimbers, and front hood skin thickness. As I just have an excerpt from the 1989 S-580 I'm not sure if the buff load of 800,000 lbs was already included or came later with the FRA rules.

So the question remains, when was the starting point to include a buff load into the locomotive design.
Regards, Volker

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Posted by erikem on Monday, August 07, 2017 10:34 PM

RME

Crashworthiness in locomotives is a radically different thing from buff and draft strength in things like RPO cars, which run in-train and aren't expected to absorb primary collision impact as a locomotive cab is.  If I remember correctly, the 800,000# standard was specifically imposed on RPOs first, as they involved Government personnel -- I don't have my copy of the 1940 version of the AAR standard handy, but I remember it specifically mentioning this.

White's book on American Railroad Passenger cars said essentially the same thing, i.e. buff and darft standards were imposed by law on RPO cars.

All the recent work I have seen with locomotive crew safety has involved armoring and reconfiguring the cab and preventing collisions from overrunning the occupied areas of the cab.  There is less concern with buckling the locomotive frame than with keeping the engine and alternator from becoming too friendly with the cab rear bulkhead, and it can be interesting to see the ways in which modern designs handle that.

I recall reading that EMD units were specifically design to buckle right behind the cabs to absorb energy. The 1961 Trains article about testing the SP K-M on Semmering garde stated that the AAR had a requirement for buff strength with limits on permanent deflections in the frame.

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Posted by VOLKER LANDWEHR on Tuesday, August 08, 2017 4:23 AM

erikem
I recall reading that EMD units were specifically design to buckle right behind the cabs to absorb energy. The 1961 Trains article about testing the SP K-M on Semmering garde stated that the AAR had a requirement for buff strength with limits on permanent deflections in the frame.

Following your hint, I checked "Southern Pacific & The KM Hydraulics". You are right. On page 37 is a short passage about the underframe stating that the underframe "must be capable of withstanding a compression pressure of 1,000,000 lbs imposed longitudinally on buffer faces without permanent deformation".

Was this a requirement just for a foreign locomotive or a general practice? If the latter how does your information about buckling by design of EMD frames fit into the picture?

Between the buff load requirement for passenger cars and AAR's S-580-1989 seems to be a large gap regarding locomotives. But then there is the requirement for the SP KM's underframe.
Regards, Volker

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Posted by oltmannd on Tuesday, August 08, 2017 8:47 AM

VOLKER LANDWEHR

I have a question about the crashworthiness of Diesel locomotives.

I found that the earliest requirements were PRR passenger cars with a buff load of 200.000 lbs in 1906 followed by RPO cars with 400,000lbs in 1912. It was later doubled to 800,000 lbs.

in 1939 the AAR made the 800,000 lbs a Recommended Practice for passenger cars and a Standard 1949 (S-034: Specifications for the Construction of new Passenger Eqipment Cars).

In 1956 it got mandatory for MU- units.

Locomotives are never mentioned. Rules for locomotives that I know were first published in 1989 with AAR's S-580. Later came the FRA and APTA rules.

Adopted the locomotive manufacturers the above buff loads volontarily? Or were there no crashworthiness measures before 1989?
Regards, Volker

 

Good question.  In all the years I was involved with new locomotive specifications (1989 to 1994) at Conrail, I don't recall any specific design requirment or testing of underframe strenght.  I do recall the improved crashworthiness items that were part of the "wide cab" design - crash posts, cab door design, etc.

-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/

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Posted by jeffhergert on Tuesday, August 08, 2017 10:00 PM

Results from a head-on collision about 1988.  

http://www.iaisrailfans.org/gallery/mishaps/Altoona_05 

http://www.iaisrailfans.org/gallery/mishaps/Altoona_04 

One train forgot a train order (to wait for a specific time or the arrival of the opposing train) and had a "corn field" meet east of Altoona, IA.  It happened on a curve, with one running long hood forward.  One crew, the one that forgot the wait order, jumped and survived.  The other crew, IIRC on the one long hood forward, didn't and were both killed.  It was speculated that because of the long hood forward they may not have seen the other train.

Jeff

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