Passenger Trains > Talgo speeds

Looks like BNSF will allow Amtrak cascades trains operating with horizon/amfleet equipment to observe posted Talgo speeds and operate with PTC in Tilt train mode.

Anyone have any more info or details on this?

Posted from iPhone

swingnose Wrote:
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> Looks like BNSF will allow Amtrak cascades trains
> operating with horizon/amfleet equipment to
> observe posted Talgo speeds and operate with PTC
> in Tilt train mode.
>
> Anyone have any more info or details on this?
>

I don't, however:

Cliffs Notes preliminary - Cant deficiency: Also called unbalanced superelevation (unbalance). The calculated speed is determined using the amount of superelevation (outside rail higher than inside rail) in inches. Equilibrium Speed is zero cant deficiency. The superelevation exactly offsets centrifugal force. Even freight train speeds are calculated with two inches of cant deficiency. Conventional passenger train speeds are calculated using three inches of cant deficieicy. That means that the speed is calculated on three inches more superelevation than is physically there.  If there is two inches of superelevation in the curve, the passenger speed would be higher as if there was five inches.

More than three inches of cant deficiency must be authorized by FRA specifically for each type of equipment. The testing involves static testing, tilting the track to the point that the high side wheels begin to unload (just below overturning). There is also active testing to see how the equipment reacts when operating at higher cant deficiency. Tilting is for passenger comfort, but tilting train speeds are also based on safely negotiating the curve (which is influenced by center of gravity). The safe maximum Talgo speed for the famous DuPont train wreck curve (for the Talgo train only, not the engines) is 44 mph. The speed limit is 30.

I have heard that Amfleet and Horizon cars have been authorized for five inches of can't deficiency. That would probably be the upper limit of cant deficiency for these cars. Talgo speed is five inches cant deficiency. The train is capable of more than that, but it has never been allowed. The problem that prohibited more in the initial testing was the F59, the F40 cab car, and the condition of some of the BN track. FRA allowed allowed six inches, but BN only allowed five inches to give them some track condition leeway. If tilting trains are not used, running time will never get better than it is now.

TAW

Thank you for this clear and informative post.

Hi All I see that Cascades # 500 past the Chehalis railcam at 09:50 today had Talgo cars including the Towmater. Cheers Greengrocer

swingnose Wrote:
-------------------------------------------------------
> Looks like BNSF will allow Amtrak cascades trains
> operating with horizon/amfleet equipment to
> observe posted Talgo speeds and operate with PTC
> in Tilt train mode.
>
> Anyone have any more info or details on this?
>
> Posted from iPhone

It was in our GTB's the recently..

TAW Wrote:
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> I have heard that Amfleet and Horizon cars have
> been authorized for five inches of cant
> deficiency. That would probably be the upper limit

That's correct. Amtrak allows operation at 5" cant deficiency for trains consisting of Capitoliner Cab Cars, Amfleet and Horizon cars and for P32, P40, and P42 diesel engines.

TAW Wrote:
The testing involves static testing,
> tilting the track to the point that the high side
> wheels begin to unload (just below overturning).

I think you mean tilting the carbody.

RRTom Wrote:
-------------------------------------------------------
> TAW Wrote:
> The testing involves static testing,
> > tilting the track to the point that the high
> side
> > wheels begin to unload (just below
> overturning).
>
> I think you mean tilting the carbody.

49 CFR 213.57(c) All vehicles are considered qualified for operating on track with a cant deficiency, Eu, not exceeding 3 inches. Table 1 of appendix A to this part is a table of speeds computed in accordance with the formula in paragraph (b) of this section, when Eu equals 3 inches, for various elevations and degrees of curvature.(d) Each vehicle type must be approved by FRA to operate on track with a qualified cant deficiency, Eu, greater than 3 inches. Each vehicle type must demonstrate, in a ready-for-service load condition, compliance with the requirements of either paragraph (d)(1) or (2) of this section.(1) When positioned on a track with a uniform superelevation equal to the proposed cant deficiency:(i) No wheel of the vehicle type unloads to a value less than 60 percent of its static value on perfectly level track; and(ii) For passenger cars, the roll angle between the floor of the equipment and the horizontal does not exceed 8.6 degrees; or(2) When operating through a constant radius curve at a constant speed corresponding to the proposed cant deficiency, and a test plan is submitted to and approved by FRA in accordance with § 213.345(e) and (f):(i) The steady-state (average) load on any wheel, throughout the body of the curve, is not less than 60 percent of its static value on perfectly level track; and(ii) For passenger cars, the steady-state (average) lateral acceleration measured on the floor of the carbody does not exceed 0.15g.

TAW

TAW, thanks for the CFR reference.  It says put the car on tilted track, not tilt the track under the car which is what I thought you were saying.
I don't know the date of this reg, but I was told by Amtrak's testing manager around 1998 that a passenger car was put on track with zero crosslevel and a force applied to the top of the carbody to simulate underbalance, and that the unloading of the wheels was measured and correlated.