The following links are to pictures of the latest work done on the new turntable pit in Altoona.

http://www.railroadcity.com/gallery/index.php?id=73

http://www.railroadcity.com/gallery/index.php?id=74

http://www.railroadcity.com/gallery/index.php?id=75

http://www.railroadcity.com/gallery/index.php?id=76

We have poured nearly 700 yards of concrete to date. Estimated completion of the concrete work is Feb 20.

Thanks

Just curious, where will the K-4 be operated upon return. Bald Eagle branch? How will it get there? or anyother branch for that matter.

Ed K cp. Laurel Run

Grew up as a teenager with 1361 on the New York & Long Branch.

We've discussed this here before, but since I note they are pouring the pit walls and foundation for the ring rail before installing the table itself, I'm still curious how they will get the table installed at exact center? Previously, there were discussions of using taut wires and plumb bobs, etc., but having operated a turntable for 20 years, I know there is little margin for error in getting it centered, lest it scrape the pit wall (or circular steel beam, if so equipped at the top of the pit) on one side or the other. Just being a half inch off center could cause a problem, and even the rails heating up in the sun can cause rubbing.

In old photos I've seen (where they enlarged turntables), they usually dug the pit bigger, installed the new table, then used it as a sort of compass to determine where the concrete forms would be placed for the new pit walls. To bridge the gaps while the old smaller table was still in place, cribbings were laid in the enlarged pit, with track extensions laid over them. I think the method I've described is illustrated in this photo, taken at the Colorado & Southern roundhouse at Trinidad, Colorado in 1923:
http://photoswest.org/cgi-bin/imager?11006035+Z-6035

I'm sure there must ba a high-tech way of centering a table with the walls already in place, I'd just like to know what it is.

First, we were lucky enough to have the blueprints from Bethlehem Steel for the table we purchased. This included blueprints for the pit and foundation and greatly aided our architects in their design work. Second, getting it centered will not be difficult as "dead center" has been drilled on the center pier using both laser and GPS technologies. There is almost 8 inches to play with (4 inches on each side) between the end of the table and the edge of the pit wall. We are also lucky to have a table that was built in two pieces. One half of the table will go into the pit at a time. Also, the material that will be closest to the pit wall at the very end of the table is not the metal bridge itself. It is a wooden crosstie with a radius cut on it lengthwise.

Thanks

It will be run wherever we can make the proper arrangements to do so. I know that sounds pretty non-commital but we are open to running the locomotive wherever a sound physical and fiscal opportunity exists to do so.

Thanks

Impressive work ( and photos) Thanks for sharing and good luck in the future.

Congratulations Scott on your impressive progress. Sure great to witness a new turntable being installed early in the 21st. Century. Let's hope it's the sign of greater things to soon follow! How long a wheelbase engine will it accomodate? Thanks, Ross Rowland

Ran accross this today: http://www.fwry.com/turntable_update/turntable_update.html.
Two turntables being installed in 2006!

The table is a 105' former RF&P table from Potomac Yard built in August of 1922 by Bethlehem Steel in Steelton, PA.

"There is almost 8 inches to play with (4 inches on each side) between the end of the table and the edge of the pit wall."

That is a typical distance between the heavy bridge itself and the pit wall, but the rails must come within an inch or less of those outside the pit, and if the table is not centered in the pit, they will hit on one side or the other. I'd be curious to hear what modern surveying devices found the exact center, and how accurate it works out in actual practice. And were any turntables ever installed that way in the pre-electronic age?

How is the RR Museum of LI's TT project coming along? It's been a few years since I was there myself giving tours of Number 39.

I will have to get you the exact brand name/make of the piece of equipment being used. I think it was made by Nikon. When they were checking the distance from the equipment anchored at the dead center point of the pit to the inside wall of the concrete forms when getting ready to pour the ringwall, I heard the foreman ask one of his crew to turn the screw on the form brace to "give him another sixteenth". That my friend is accuracy.

As far as whether tables were installed that way before the electronic age, I'm not sure that's relevant. We would be crazy to not take advantage of the technology available to us today. We can stand at the center of the concrete pier that will support our center bearing and with this equipment tell you EXACTLY (down to the sixteenth) how far it is to any point along the ring wall.

Thanks

Measurements as fine as 0.006 of a foot are readily repeatable with modern, adjusted surveying equipment and proper procedures. Finer precision can be obtained with specialized equipment that is normally used for laying out airplanes, ships etc., but standard total station would be fine for this purpose.

I had the privilege of calculating the center point for the Hobby Eberle Telescope at the McDonald Observatory in west Texas. The telescope's mirror and framing was constructed in Germany based on our measurements. It fit like a glove, but I was a little nervous for awhile.

I would be more inclined to use a total station over GPS for high precision work.

Andy Nold
Tx Registered Professional Land Surveyor

And... this is far more precise than any of the other parts of the system. The center bearing is going to have some wiggle room in the bolt holes to allow fine adjustment as it is set and grouted in place; the ring rail bolts will have the clearance in the rail clips for tweaking, unless they are going to bed wood blocks in the ledge for the ring rail, which I tend to doubt. Anyway, all the radial table end wheels I've seen are an inch or two wider than the railhead, so positioning +/- an inch is likely close enough. After the rails are attached to the bridge deck, and confirmed centered, Then they can lay the approach rails to the table and gage whatever they want for clearance.

folks,

for thise who are interested in turntables; the Colorado Railroad Museum built themselves a 4 stall round house with turntable a couple of years ago. The actual table came from Kansas I think.

Ithink the interesting thing about is that it is duel gauge. The table and the round house can handle either standard or narrow gauge equipment.

Take a look at the museums web site at www.crrm.org for some pictures of it

Ted Miles!