AEM-7 status

A bridge des not just respond to weight, but to much weight even over bigger base creates a sine wave within bridge structure. and with most bridges on New haven being over 100 year old , there will never be a change.

This might help explain what Dutch Railnut is talking about in laymans language
https://www.sciencedaily.com/releases/2 ... 080801.htm

DutchRailnut wrote: ↑Thu Dec 12, 2019 1:48 pm A bridge des not just respond to weight, but to much weight even over bigger base creates a sine wave within bridge structure. and with most bridges on New haven being over 100 year old , there will never be a change.

In other words. the New Haven didnt build stuff as good as the PRR. LOL

ApproachMedium wrote: ↑Mon Dec 16, 2019 1:59 am
In other words. the New Haven didnt build stuff as good as the PRR. LOL

That may be too simplistic. Consideration has to be made of distance between axels, trucks, distances between units , etc. distance between pans. New haven has a bunch of swing draw bridges which may have different loadings. Note all replacements appear to become lift except maybe one bascule (2050 )

DutchRailnut wrote: ↑Thu Dec 12, 2019 1:48 pm A bridge des not just respond to weight, but to much weight even over bigger base creates a sine wave within bridge structure. and with most bridges on New haven being over 100 year old , there will never be a change.

Vibration modes of bridges are always checked with new bridge designs and unless the designers screw up badly nobody ever hears of them. Bridge vibrations were known for quite a while before New Haven even existed, but I do agree that is it unclear to what extent they were taken into account when those century old bridges were designed. I, in particular, have been well aware why the military does not march on bridges. In general there are two ways to address vibration modes: (1) by adding energy absorbing materials such are rubber and (2) by adding mass. While every bridge is different, it is unusual for a heavier load to excite vibration modes not excited by lighter loads which is why I questioned those statements in first place. Most likely the rule we are discussing was a crude attempt to address some concern many decades ago and has remained on the books since then (and for a good reason, if it ain't broken don't fix it). I do not expect that if anyone wrote a new rule book from scratch this rule to keep this rule as written.

Most bridges on New Haven are over a century old and had at least 3 decades of deferred maintenance, so yes there is a big concern.
Metro North can't afford a bridge failure not even a temporary.

east point wrote: ↑Mon Dec 09, 2019 9:28 pm Have no first or second hand knowledge but have heard that major substation transformer building lead times are in the ball park of 2 years +.

Depends on the exact characteristics needed and the style of transformer, but it isn't particularly quick. Vacuum sealed transformers, for example, have to sit for up to a year between installation and energization, never mind the lead time and installation.

Dutch is right, the bridge problem has just as much to do with age and lack of maintenance as it does with design. New Haven and Penn Central were flat broke and since there was no valuable freight moving across those bridges, they didn't get much money. Don't forget that the same PC system saw quite a few entire classes of equipment retired much earlier than expected (4400 washboards for example) because they let them slide in terms of maintenance. Amtrak and Metro North are getting far more life out of the M2 and Genesis than PC got out of their E's and 4400's.

Even out of the PC context, there are certainly older bridges that are speed/weight restricted. Alaska railroad comes to mind - they crawl across Hurricane Gulch not just for the view, but for the age.

Does anyone know what the sign on the front of the lead work diesel and on the rear of the last AEM-7 said? I saw two pointless arrow Amtrak logos on each side of the current three sheets logo, and some writing below. No video I’ve seen caught the signs legible enough to read.

Amtrak706 wrote: ↑Fri Dec 27, 2019 2:23 pm Does anyone know what the sign on the front of the lead work diesel and on the rear of the last AEM-7 said? I saw two pointless arrow Amtrak logos on each side of the current three sheets logo, and some writing below. No video I’ve seen caught the signs legible enough to read.

Ben

"Farewell and Goodbye, Amtrak's Beloved Workhorse, The AEM7."
"Last Run Wilmington, DE to Davisville, RI."

Very classy touch. Nice job to whoever took the time to do that.

That picture seems to answer the question of who bought them.

A scrapyard that is not ...

superstar wrote: ↑Fri Dec 27, 2019 10:36 pm That picture seems to answer the question of who bought them.

Not really. RPI is in California. The only yard there is with the Seaview RR. Until they start heading west, their final destination is unknown.