Turntable Space

[ndbprr]

I know I am in the minority in regard to my opinion of roundhouses and turntables.  I do not want to waste the amount of space an entire engine terminal properly laid out with ash pit, coal tower, water tower, sand house, ready tracks, incoming track or tracks requires.  On a previous12' x 20' around the walls layout the space amounted to almost 25% of the railroad.  Unless one is modeling a division point the need doesn't exist.  I know engine terminals are liked by many people including myself but they are better left for club situations where space is less of a consideration.  The same space could easily hold two or three industries.  Now at my major yard I do have a couple of ready tracks to store yard engines but that will be it on a railroad under construction that will occupy 15' x 40' when finished. Space is too hard to come by to waste it on an engine terminal.

[wedudler]

You can download from Walthers the turntable data, all technical instructions as a .pdf file.

Wolfgang 

[MisterBeasley]

This is an arial photograph of my turntable and roundhouse area:

(Click on the picture for a larger image.)

This is an Atlas turntable, which is 9 inches across in HO, about 66 scale feet.  For your 90-foot turntable, all of your dimensions will be about 1/3 larger.  The overall space shown here is 24 inches across, from the leading edge of the turntable to the back of the roundhouse.  The roundhouse itself is about 16 inches top-to-bottom in the picture.  If you add in the satellite tracks (with the GP-9's on them in the photo) the whole facility is 24 inches top-to-bottom.

So, all other things being equal, if you built a facility with this configuration, using a larger turntable and a correspondingly larger roundhouse, it would be about 32 inches square.

Another issue is the size of the "apron" in front of the roundhouse.  This is dictated by the angular spacing of the tracks.  For the Atlas, the spacing is 15 degrees, but larger roundhouses are 12 or even 10-degree spacings.  (The Atlas roundhouse is matched to the 15-degree indexing of the turntable.)  With a tighter spacing, you have to go further from the turntable before the tracks separate enough for the roundhouse, so you made need a few more inches there.

[fwright]

You need the diameter of the turntable.  Then the length of any engine (round?) house tracks, which as Tom states, should be a little longer than the turntable bridge.  If the roundhouse tracks are the same length as the turntable bridge, how good are you at spotting a maximum-length locomotive inside the roundhouse with no extra track?

Another aspect many forget is the distance between the roundhouse and the turntable.  To me, it looks a little funny not to have at least a locomotive length between the two, yet this is how the Walters roundhouse is set up (to conserve space).  I just have a problem with the locomotive entering the turntable before it is even out of the roundhouse, and vice versa.

If you put the steam servicing (coal, sand, water, ash pit) on the arrival/departure tracks, more  than a locomotive length will be needed there as well.  If the roundhouse tracks are opposite the approach/departure tracks (common prototype practice), you are looking at a total of about 5 turntable diameters for a convincing, though still compressed scene.  This can be reduced to about 3.7 turntable diameters if the space between turntable and roundhouse is minimized.  Putting the roundhouse on the same side of the turntable as the approach/departure tracks knocks the length required down to about 2.5 diameters, but you need more width, and you have deviated quite a bit from common prototype practice.

my thoughts, your choices

Fred W 

[TomDiehl]

We'll have to assume you're talking about HO scale. The 90 foot diameter turntable is slightly over a foot in diameter, and the pit sides would push that to about 13 inches.

As for the roundhouse, it depends on which one you're planning on building. If you're looking at outdoor storage tracks as well, commonly called garden tracks, to make a full circle, figure each track to be about 30% to 50% longer than the turntable track. That would figure out to almost a 4 foot diameter area. A less-than-circle facility would remove a "slice of the pie."

[Butlerhawk]

How much space does it take to properly install a 90' turntable; and how much more to add a 3 space roundhouse? Thanks for your help.