Still can't understand why some of those catenary poles are so weirdly high!
But they are not consistent in height.Possibly so they can be used as supports for the 25Kv catenary wires that would be used to electrify the commuter rail tracks next to the Green Line tracks.
thanks for the info, good to hear they're back testing straight away after the shut down.Was a little too far away to snap a good pic, so this is somethign of a tease, but I just caught a test-car passing through the Gilman Square station (slowly, as you'd imagine), coming from the Tufts direction and heading towards E Somerville. Been waiting forever to see that!
Maybe you saw them at different angles?But they are not consistent in height.
But they are not consistent in height.
(Here's to hoping an aB poster with magical inside info can share a happier conclusion than mine)
so in layman's terms.There are something like 800+ OCS poles along both branches of the extension. A portion are mounted on top of foundations with a base plate, but the vast majority are set inside drilled shafts (you can see both in the photos above). The poles mounted on base plates should be pretty consistent. However, considering the variability in soil conditions along the length of the corridor, the drilled shafts extend down to varying depths (including the OCS poles set within them). It would be unreasonable to design and fabricate 800+ individual poles to exact lengths, so designs need to be grouped together based on soil conditions. Additionally, the poles would get fabricated in 5ft increments instead of an exact length for each. So their overall length would be determined by an absolute minimum length that they need to be on the low end - and then what ever is left over (less than 5ft) sticks up above that.
So imagine one pole may require a shaft with 17ft embedment, and 25ft extension - you would use a 45ft pole that has 3ft extra length at the top. Then the next pole has soil conditions requiring 15ft embedment.. a 40ft pole would be used with no extra length on top.
Then as you mentioned, some poles have additional AC distribution above the DC feeders, and that can cause an even larger disparity pole to pole.
so in layman's terms.
They're all different sizes because the ground they're in is different?
Why not put them in then top them off at the same height above ground?
Only the AC poles being higher but them also being uniform with each other?
yea, I guess it would be aesthetic. I presumed it would be a given.Would doing that be for purely aesthetic reasons? Just curious, not trying to be snarky. I agree it'd "look nicer" if everything was more uniform, for sure, but given the massive amount of work and $$$ involved just to get things functional and reliable, I'd rather the T/the state/the Feds/whoever spend what money is available on actual service (and, who knows, someday maybe even grander aspirations like a N/S connector) than blowing cash on sawing off the tops of these things, just so that everything's more "pretty."
There really are some pretty basic quality standards in construction that this violates.
If you had a fence installed around your home, and every post was a different height, you'd likely be pissed. Even if the fence was 'functional", it is still poor quality.