Heat knocks out light rail

[ORNHOO]

Tri-Met in Portland, OR shuts down MAX light rail trains due to 100 degree plus heat wave.

https://www.oregonlive.com/commuting/2021/06/trimet-suspends-max-wes-lines-until-tuesday-citing-heat-related-mechanical-issues.html

 

[Overmod]

Reading between the lines, this is an electric-power thing more than an equipment operating-temperature thing.  Note that the buses keep running just fine.  Wonder if battery hybrids will do the same?

[blue streak 1]

2 quick thoughts.  #1 Might be worry about rail kinks.  Wes rail probably that as it is not electrified.  #2  CAT might sag too much.  One of our posters will have to tell us if the lines are sagging and also how close to the ground the weights are ?

How are BNSF and UP dealing with the possibility of rail kinks ?

[BaltACD]

blue streak 1

...

How are BNSF and UP dealing with the possibility of rail kinks ?

Heat Orders - Just like they do in known hot weather territory.

[blue streak 1]

Not sure but one item on TV showed a CAT insulator fried.  Maybe CAT sagged too much and they had to turn off power ?

[Overmod]

blue streak 1

Maybe CAT sagged too much and they had to turn off power ?

But isn't it constant-tension?

[ORNHOO]

Overmod

But isn't it constant-tension?

Yes, the constant tension being maintained by counterweights on the suspension cables. Apparently, when Tri-Met engineered this system they did not take into account Global Warming, the suspension cable expands as the temperature increases, the couterweights are on the ground at temperatures above 100 degrees fahrenheit.

[7j43k]

Anyone think of digging a hole?

Apparently not.

Ed

[ORNHOO]

Temperatures are rising in the Portland area again: https://trimet.org/alerts/hotweather.htm

The counterweights are suspended between the webs of the "H" section catenary support poles. If Ed wants to volunteer to dig some holes they would have to be dug through the reinforced concrete footings for the poles. Engineered in the Holocene, operating in the Anthropocene.

[7j43k]

ORNHOO

Temperatures are rising in the Portland area again: https://trimet.org/alerts/hotweather.htm

The counterweights are suspended between the webs of the "H" section catenary support poles. If Ed wants to volunteer to dig some holes they would have to be dug through the reinforced concrete footings for the poles. Engineered in the Holocene, operating in the Anthropocene.

 

 

I'd sure like to see a picture of that.  It SOUNDS like they placed the counterweights in an inaccessible location (between the webs).

 

Ed

[BaltACD]

ORNHOO

Temperatures are rising in the Portland area again: https://trimet.org/alerts/hotweather.htm

The counterweights are suspended between the webs of the "H" section catenary support poles. If Ed wants to volunteer to dig some holes they would have to be dug through the reinforced concrete footings for the poles. Engineered in the Holocene, operating in the Anthropocene.

Shorten the cable attaching the counterwights to the wire they are balancing.

[Overmod]

7j43k

 

The counterweights are suspended between the webs of the "H" section catenary support poles.

I'd sure like to see a picture of that.  It SOUNDS like they placed the counterweights in an inaccessible location (between the webs).

The amount of weight needed can be substantial (SCAT tension is 3000# on the trolley and 4500# on the messenger) and there are forces acting other than vertically on the suspending support.  The problem with SCAT is that it was largely designed to live between the double tracks, in what was already a minimum distance; accommodating the BWAs ('balance weight assemblies') partly within the h-beam channels makes engineering sense.

There are materials other than 'the usual' that could be used to increase the counterweight density (to permit a shorter vertical BWA stack height to facilitate Balt's suspension shortening -- keep in mind it will get cold again as winter comes); a secondary stack might be provided outboard of the pole in line with track to assist load; the mechanical advantage of the original stack suspension might be changed slightly from nominal 3:1) -- that sort of thing, far easier than machining a bunch of frogs and regauging/profiling a full set of mandatorily one-piece-cast wheels... 

...but this is a place where a core drill and some strategic chipping ought to have particular utility. I don't know the sag for an 'extra' 10 degrees as I don't know if SCAT divides the tensioning separately from the electrical sectionalization but the vertical change of the base of the BWAs can't be more than inches.  I am sure a circumferential metal liner, rubber moisture barrier, etc. can be provided to eliminate rain-drainage concerns.