MTA Purple Line Bethesda - New Carrollton Light Rail

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Re: MTA Purple Line Bethesda - New Carrollton Light Rail

Post by farecard »

I went through S/S just before midnight Thur. There was a large tracked double crane on a wood pad preparing to lift what appeared to be two tall, skinny, i-beams off a trailer parked just south of Wayne.

<https://photos.app.goo.gl/NkuCiinpWfkVJrWw8>
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Re: MTA Purple Line Bethesda - New Carrollton Light Rail

Post by farecard »

Stopped by the Metro garage last night and chatted with a PL worker. The crane is a Manitowoc 450 ton model. Just getting it there in pieces required ~7 special permitted shipments. It's sitting atop a WSSC watermain that has many people nervous. It has a ballast that extends out automagically as required by the loading

They have bridged the Red Line with 2 of the 4 girders needed. (Seen in my previous post.) They must be installed in the right order to ensure they can be placed correctly. While the Red Line is shut, CSX is single-tracking on their SW track; a CSX employee was there to coordinate the movements. Manitowoc had several cameras on and around the crane over the weekend; maybe they'll release the bits at some point.

They will be taking a break of two weekends before bridging Colesville Rd; I'm not sure if they'll be installing the steel east of Colesville towards Bonifont in the interim but I doubt they'd leave an a$$et like the Manitowoc idle for more than a lunch break.

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Re: MTA Purple Line Bethesda - New Carrollton Light Rail

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Stopped by the Metro garage last night and chatted with a PL worker. The crane is a Manitowoc 450 ton model. Just getting it there in pieces required ~7 special permitted shipments. It's sitting atop a WSSC watermain that has many people nervous. It has a ballast that extends out automagically as required by the loading


Not all of the out riggers will be bearing on the ground above the water main. There be at least 4 out riggers. If it is a tracked crane again not all the weight will bearing on the ground above the water main. In either case mats will placed under bearing points of the crane to distribute weight over a larger area. During the lift the distributed weight to the ground will be something of under 500 lbs per square foot. The concrete under the asphalt has a compression strength of at least 2,500 lbs per square inch.
Last edited by Sand Box John on Mon Feb 17, 2020 10:31 pm, edited 1 time in total.
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Re: MTA Purple Line Bethesda - New Carrollton Light Rail

Post by farecard »

I'll tell WSSC it's nothing to worry about.......

They reportedly lack such confidence; they have the main out of service during the crane use, and a repair crew on standby. The Manitowoc is sitting on a bed of 8"x8" (or bigger....) timbers extending past the treads on both sides.

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Re: MTA Purple Line Bethesda - New Carrollton Light Rail

Post by drwho9437 »

Note sure where you got the break time from. If they managed the last beam then they are done the tracks but WMATA still has the Red line shut on the 29th. It took them a long time to move the crane to Colesville. I would just guess they are going to move the crane again to the area that is fenced, for hanging stuff over Colesville in two weekend's time. Maybe they can just move it directly and it won't take any time? But we shall see. If the no time move is true they would just put everything up but Colesville and then do that last if you are right about the order. So far it has been crane operations every other weekend.

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Re: MTA Purple Line Bethesda - New Carrollton Light Rail

Post by farecard »

Maybe I misunderstood the PL employee but....

I would think they would want to put the beams in order, rather than fitting the Colesville beams in between the ones placed before and after them. ("Off by THAT much, Chief...") For that matter, I doubt they can put the beams along the garage in place except on weekends; with the station open there are too many people around at risk.

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Re: MTA Purple Line Bethesda - New Carrollton Light Rail

Post by drwho9437 »

The certainly can work inside the enclosure area to hang stuff, they wouldn't be lifting anything over anyone. I don't know when they will of course but they could, people do walk on the sidewalks even on the weekends...

As for the beams not meeting, that is the likely purpose of the temporary steel structures. The beams are not tied to the concrete yet, though in the end they have to do everything to some tolerance the holes are already in the supports that it has to mount to, it isn't a little to the left kind of thing, so they can bolt it together in principle in any order they want (presuming the topology of the steel parts allows for it).

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Re: MTA Purple Line Bethesda - New Carrollton Light Rail

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> The certainly can work inside the enclosure area to hang stuff, they wouldn't be lifting anything over anyone. I don't know when they
> will of course but they could, people do walk on the sidewalks even on the weekends...

If/when a megaton beam gets loose, it's not necessarily going to fall straight down and sit there.

When I was there, they had a worker blocking the sidewalk at intervals.

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Re: MTA Purple Line Bethesda - New Carrollton Light Rail

Post by drwho9437 »

They have never closed the sidewalks for any operations. People do walk around there even on the weekend and the buses go in and out too all weekend on the levels they aren't closing off. Only rail operations have been suspended so far. They just built standard things might fall on your head protection for dropped bolts where it crosses pedestrian areas.

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Re: MTA Purple Line Bethesda - New Carrollton Light Rail

Post by drwho9437 »

Does anyone know what sort of track signaling the Purple Line will use?

It seems like the operators have to be able to stop for pedestrians and cars in some places so perhaps it is purely a squishy human to drive the thing and no computer control? Speed controls I would personally hope exist and regular block signaling as well... Seems like they would want to know where their trains are somehow but I have no info on how they will do any signaling on this thing.

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Re: MTA Purple Line Bethesda - New Carrollton Light Rail

Post by Sand Box John »

drwho9437
Does anyone know what sort of track signaling the Purple Line will use?

It seems like the operators have to be able to stop for pedestrians and cars in some places so perhaps it is purely a squishy human to drive the thing and no computer control? Speed controls I would personally hope exist and regular block signaling as well... Seems like they would want to know where their trains are somehow but I have no info on how they will do any signaling on this thing.


The signaling will likely be similar to what WMATA uses with no automatic control. Traffic signals will be integrated in areas of street running.
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Re: MTA Purple Line Bethesda - New Carrollton Light Rail

Post by STrRedWolf »

Sand Box John wrote:
Mon Feb 24, 2020 8:04 am
drwho9437
Does anyone know what sort of track signaling the Purple Line will use?

It seems like the operators have to be able to stop for pedestrians and cars in some places so perhaps it is purely a squishy human to drive the thing and no computer control? Speed controls I would personally hope exist and regular block signaling as well... Seems like they would want to know where their trains are somehow but I have no info on how they will do any signaling on this thing.


The signaling will likely be similar to what WMATA uses with no automatic control. Traffic signals will be integrated in areas of street running.
Light Rail in Baltimore uses ATP (Automated Train Protection) which controls track speed, but otherwise it's all humans at the controls. Hopefully they won't try to stretch out the ATP signalling too much, because when it drops, it slams the brakes.
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Re: MTA Purple Line Bethesda - New Carrollton Light Rail

Post by farecard »

This weekend's S/S - Colesville shutdown had a different crane. The monster was gone; I suspect it was needed only for reaching across the tracks. Instead there was a large telescoping wheeled crane. Its outer cylinder was > 1 ft in diameter & had 5+ sections within. When I went by it was not in use.

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Re: MTA Purple Line Bethesda - New Carrollton Light Rail

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This weekend's S/S - Colesville shutdown had a different crane. The monster was gone; I suspect it was needed only for reaching across the tracks. Instead there was a large telescoping wheeled crane. Its outer cylinder was > 1 ft in diameter & had 5+ sections within. When I went by it was not in use.


Pictures from post at reddit.com/r/SilverSpring

Seems the contractor used multiple hydraulic truck cranes.
John in the sand box of Maryland's eastern shore.

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Re: MTA Purple Line Bethesda - New Carrollton Light Rail

Post by drwho9437 »

Progress in Silver Spring has been well documented, does anyone have any photos or info on PG county stuff or even Bethesda? I know a lot of it is off limits between Silver Spring and Bethesda though.

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