Passenger Trains > Amtrak Minimal Axle Count Requirement

I hear a lot about the host RR’s requiring Amtrak to have a minimum number of axles to properly activate the signal systems. Let me ask what has changed? In the pre-Amtrak days when passenger service was waning I remember seeing a lot of single locomotive + 2 or 3 car consists.

Posted from iPhone

Same question on this from me too. There were even Budd RDC's, and before that, - "Doodlebugs." It was often reported that the "Doodlebugs" needed a coach or caboose attached to them to activate the signals, but they operated with just one car over time. So what has changed? 

johnambrose Wrote:
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> I hear a lot about the host RR’s requiring
> Amtrak to have a minimum number of axles to
> properly activate the signal systems. Let me ask
> what has changed? In the pre-Amtrak days when
> passenger service was waning I remember seeing a
> lot of single locomotive + 2 or 3 car consists.
>
> Posted from iPhone

Lawyers!!!

When railroads operated their own trains they could take their own risks. The current situation has Amtrak running at the mercy of host railroads who can set minimums and not care about how much it costs to meet the minimum.

Perhaps, it is related to technology change with the protection being timed according to train speeds.

Amtrak does not have any such thing as a minimal axle count for train makeup.

That is purely the host railroad instructions.

But, surely, PTC doesn’t require an axle count- does it?
SR

PTC does not require a minimum axle count, however the technology becomes less precise the shorter a train is.  In fact, light power moves are not required to operate with PTC on some RR's.  Just to clarify, the minimum axle requirements being discussed here are required to properly shunt the grade crossing signal circuits; not the block signal system.

BoilingMan Wrote:
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> But, surely, PTC doesn’t require an axle count-
> does it?

On some RR's, PTC does have a minimum car count before you can operate with the system initialized.

Posted from Android

My understanding is that CN is the only road requiring large axle counts, and only on the former IC.  This stems from an incident - maybe more than one - several years ago when grade crossing signals failed to activate.

Dave

The UP has a minimum axle count requirement for the four daily River Runners between Kansas City and St Louis.   

See the thread at   https://www.trainorders.com/discussion/read.php?4,4810687 



Edited 1 time(s). Last edit at 06/15/19 19:49 by wister6813.

The N.Y.Central had an excitation device on it's Budd RDCs that would allow single cars to shunt grade crossing and signal circuits.

CN has a minimum in Michigan on former GTW lines.  Reason for this is an accident several years ago in Charlotte.  A train failed to activate crossing signals and a woman motorist died.  However, following this, CN's own Santa Train ran for years without the axles required on Amtrak.  Amtrak trains (350 and 355) often feature a deadheading brand new Viewliner baggage car to fill out the train.

raytc1944 Wrote:
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> The N.Y.Central had an excitation device on it's
> Budd RDCs that would allow single cars to shunt
> grade crossing and signal circuits.

I wonder how this worked?

I remember hearing how the Central tried running Budd Cars on the upper Harlem, but because they did not reliably trip the crossing signals the experiment was abandoned.



Edited 1 time(s). Last edit at 12/31/23 08:59 by restricted_speed.

perhaps in humid areas with a lot of rust on the railhead it is  an issue?

It has to do with the loss of shunt across the board, there have been incidents with not getting adequate crossing start time and falling off the dispatcher screen/approach lit signals turning off and such as well.

As far as I know, The US is #1 in advanced MAC (Minimum Axle Count) signal detection.

In Europe, China, and Russia railroads have to rely on so-called "other" technologies and so do not enjoy the advantages of hauling around dead weight. And the extra wear-and-tear provides more work & money for the American worker.

I wonder how Bangladesh handles detection issues.

The problem isn't that a single car can't shunt the track circuit, it's that it might not at an unacceptably high rate.  Look at how quickly tracks can rust after a rain storm.  That is where one might expect to see the occasional grade crossing failure.  CN also may have adjusted its track circuits to prevent spurious occupancy indications.  Combined with light rust and gaps in traffic could lead them to requiring a high axle count for no other reason than to have 2 or 3 cars breaking the rust and then 2 or 3 cars shunting the track circuit.

Back in the 1960's, the Milwaukee Road ran off-peak consists to Fox Lake of an E-8 and a Gallery cab car, and plenty of 2 car lcoals thrughout Wisconsin. It rains and snows a lot there. How'd they do that ? 

joemvcnj Wrote:
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> Back in the 1960's, the Milwaukee Road ran
> off-peak consists to Fox Lake of an E-8 and a
> Gallery cab car, and plenty of 2 car lcoals
> thrughout Wisconsin. It rains and snows a lot
> there. How'd they do that ? 

My guess is that there was no speed sensing. If a shunt occurred, the gates came down. If it was a (slow) freight, you just had to wait at the gate.