Green Line Extension Lechmere to Medford

Railroading is a pretty old business; been around since the 1800's. So now in the 21st Century we can't even get something as simple as the track gauge correct on a new project? If we can't even build a railroad track correctly we've got a much bigger problem I'd say.

Shades of the Big Dig.............. I'm completely familiar with government incompetence having worked for a county government for twenty-five years, but this is over the top even for government.

West Point:
1. I haven't heard/read what the actual gauge error is. The FRA gives 56" as absolute minimum for Class 1-5 track.
2/3. Rail/wheel interaction is designed around canted tie plates. Poor quality control at the pre-plating site might have missed backwards plates. Backwards plates would increase the gauge slightly, but not out of tolerance. Taller rail would decrease the gauge slightly, but again not out of tolerance.
4. Rail head width could be an issue, but it hasn't been mentioned to date.
5. Incorrect plates could also cause problems, but doesn't match the "slow in segments, ok in others" symptom.
6. I have a copy of the T's Green Line Track Standards, but haven't had time to proofread it looking for this.

I'll guess that most or all speed restrictions are on curves. The axles of most trolley trucks are held parallel, so curves force the wheel flanges against the rails. Below a certain curve radius, the rails need a slightly increased gauge to avoid excessive wear and risk of a flange climbing up the face of the rail. You can reduce the risk by diligent greasing of the rail face, but that's messy at best and also expensive to staff.

more possibilities.
6. What if the tie plates were too small? That is especially the inside gauge side. Could the plates have sunk into the ties on the gauge side?
7. What is along with #6 the ties were of too soft wood allowing that to happen?

Just to clarify . Light rail oversight & specifications are controlled by the FTA not the FRA.

Tie plates have to be enough wider than the rail to have spike holes - at least one inch on each side. Pandrol clip plates extend a minimum of 2 inches beyond the rail base on each side. I suppose you could make them much narrower than the tie, but that would be conspicuous. For trolley axle loads to drive plates into ties, they'd have to be made of something like poplar. Which wouldn't hold spikes either. I'm sticking to a badly designed jig at the pre-plating site.

The book I use for track work at Seashore is the FRA's, because they give it out. I doubt the FTA differs much.

Are ties manufactured with the plates in place, or are they attached on-site? If they're manufactured with the plates already attached, I'd be asking where else these ties were used.

Wooden ties are manufactured without plates in place; concrete ties are manufactured with anchor holes in place, but plates are mostly attached later (either onsite, at the factory, or at an intermediate preparation plant), although plates could be cast into the concrete.

jbvb wrote: ↑Sat Oct 21, 2023 5:49 pm I'm sticking to a badly designed jig at the pre-plating site.

This is what happened when I was working for a contractor doing trackwork on one job, we had a very reputable track material supplier pre-plate the ties who somehow messed up the jig. They had to pay us to have our crews fix it. Very costly.

In the Boston Globe article, GM Eng says that the fix will involve removing the tie plates, filling in the holes with dowels, and reinstalling the tie plates in the correct positions.

An unconfirmed source told me that the rails are 55.5" in gauge, which is half an inch out of tolerance, and an inch narrower than standard gauge.

diburning wrote: ↑Mon Oct 23, 2023 3:11 am In the Boston Globe article, GM Eng says that the fix will involve removing the tie plates, filling in the holes with dowels, and reinstalling the tie plates in the correct positions.

I would have guessed that the cost of a new tie would be less than the labor involved in doing ^ that to existing ties. And I would also assume that replacement ties would have a longer service life than rilled and re-spiked ties.
But what do I know, my only track building experience is with plastic tracks that snap together.

diburning wrote: ↑Mon Oct 23, 2023 3:11 amAn unconfirmed source told me that the rails are 55.5" in gauge, which is half an inch out of tolerance, and an inch narrower than standard gauge.

From the Trains News Wire article linked to previously:

The Green Line, like other MBTA transit lines, is standard gauge, or 4 feet, 8½ inches. WFXT-TV reports the construction contract required a track gauge within a sixteenth of an inch of that standard in either direction, while the threshold for slow orders is anything narrower than 4 feet, 8 1/8 inches. Currently, the entire extension is above the slow-order threshold, but about a half-mile on the Union Square branch and 2.7 miles on the Medford branch is narrower than the 4 feet, 8 7/16 inches permissible under the contract.

There is no way some pegged and re-drilled tie, outdoors in the winter, is going to have full life expectancy. If you move the fastener (what type of fastener are they using these days?) 1/2" it will probably be half in the peg and half outside the peg. Also how much damage has been done to the wheels.

I'm just sitting here thinking... if we're talking about just an inch or potentially less, wouldn't it be easier and cheaper and faster to just get a bunch of special custom made tie plates that hole one side of the rails over an inch and be done with it? Then you don't have to mess with replacing tires or replacing whole track panels or 'pegging' ties etc etc. You would just need some way to easily tell a special plate from a standard plate so future trackwork doesn't mess it up again.

l008com wrote: ↑Wed Oct 25, 2023 2:42 am I'm just sitting here thinking... if we're talking about just an inch or potentially less, wouldn't it be easier and cheaper and faster to just get a bunch of special custom made tie plates that hole one side of the rails over an inch and be done with it? Then you don't have to mess with replacing tires or replacing whole track panels or 'pegging' ties etc etc. You would just need some way to easily tell a special plate from a standard plate so future trackwork doesn't mess it up again.

Maybe in the very short term, but in the long term, it is better to use standard tie plates simply because special plates at special locations will be an extra logistics and maintenance concern later.

You still have to remove and install a tie plate. The cost of epoxy or wooden plugs is less than a steel? tie plate.