CSX Cumberland Division

[Bob]

The Railroad Bridges. Of the two railroad bridges at Harpers Ferry, the 1931 span is by far the simplest to model which is fortunate as it is closest to the aisle and so is more visible than the 1894 span.  While I can’t find a detailed description of this deck girder bridge, I do know that most of its sections are 100-feet long.  Using the distance measuring tool on Google maps, I measure the total length of the bridge at 1360 feet, with a 60 foot section extending over Sandy Hook road (see photo), followed by a succession of 100-foot spans.  Thus, I believe that there are 13 bridge piers – 11 are in the river while 2 are on land on the Maryland-side.  The 1894 bridge, by contrast, will be much more difficult to model as it has (in the Maryland to the West Virginia direction) four deck spans of 85.5’, one deck span of 100’, one of 34.6’, and three Pratt truss spans of 140’ in length.  Not only this, but the western end has a turnout on the bridge that diverts the mainline to the Shenandoah Branch; the original mainline alignment is now out of service, with the tracks overgrown and extending to the parking lot of the HF train station.  The bridge is sufficiently wide for two tracks, but carries only one with the Appalachian trail occupying the southern-half of the bridge.  The trick for this bridge will be the Pratt trusses – TrainCat, now sadly no more, produced a near perfect match in brass (163 feet in length); nothing presently available even comes close.  So, this bridge will wait until someone produces a double-track width Pratt Truss close in style to the 1894 bridge, or I bite the bullet and see if it can be 3D printed.

My model 1931 bridge is 7’6” feet in length, or 1,200 feet which is 88% to scale – not bad!  But, how to put a bridge of this length together? Lance came up with what I thought was a truly brilliant design: he laid MicroEngineering code 55 bridge flex track directly on top of aluminum channel measuring ½” by ½” that was then cut to the correct length.  Each of the two tracks rests on its own channel, with the two channels being linked to each other by joiners at approximately 18” intervals.  The first figure has 3 photos showing the two bridges in their entirety, a close lookup down on the 1931 bridge showing one of the joiners, and a rather blurry photo from below showing the two aluminum channels with the 1894 bridge in the background (with the rock runner on it).  The ties overhang the channel by about 1/8” on each side.  As a result, if I slide the rail joiners off either end, I can lift the entire bridge out can carry it to the workbench.  Lance’s idea was that I could simply glue deck girders to the aluminum channel, thus hiding the channel that provides structural integrity. [ Guests cannot view attachments ]

The deck girders. 100 foot deck girders are not available in N-scale, but MicroEngineering produces a decently detailed 80-foot girder.  Thus, I was faced with three choices:

1.   Use the commercially available 80-foot girders, with would result in 15, 80-foot long sections that would necessitate 13 piers and two abutments. One pier is next to Sandy Hook road, one is next to the C&O canal towpath, and the remaining 11 would be in the river.
2.   Since the girders will not be weight bearing, I could use a razor saw and splice an additional 20-foot section to the end of each 80-foot girder, giving me the real-life 100-foot length.  This would result in 12, 100-foot sections, necessitating 10 piers and 2 abutments.
3.   Have a 100-foot plate girder 3-D printed.  Ngineer makes a very nice 60-foot plate deck girder, so extending this to 100-feet should be possible.

I decided to go with option #1 as this fortuitously resulted in the correct number of bridge piers: 2 on land, 11 in the river.  I wish I could say that I had the foresight to plan this ahead of time, but have to admit that this was really a case of good fortune: the eyes should be drawn to the piers, and I find that having the prototypical number is quite satisfying.

The plate deck girders from MicroEngineering have evenly spaced vertical ribs; those on the 1931 bridge are more closely spaced, and are in some places variably spaced.  I decided that this distinction was not worth worrying about.  However, the ends of the 1931 bridge girders are at a slight angle as shown in the photo, I suppose to give the space needed for the angled bridge shoes (see Figure).  As it turns out, the MicroEngineering 80-foot girders have vertical ribs just a scale 3’ from each end.  Using a razor saw, I cut the girders at an angle, thus replicating the prototype and giving enough space for the bridge shoes (see Figure).  As for the bridge shows, Erik from Ngineering kindly designed shoes that more closely mimic those used on the actual 1931 bridge (see Figure).
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Bridge piers. We don’t have a large number of commercially available bridge piers in N scale, and I could find none that come close to those used on the 1931 bridge which are poured concrete with obvious horizontal lines (see Figure).  On a recent trip to Harpers Ferry, I was able to get a good look at the pier that is next to the C&O canal towpath, and armed with a tape measure I now have rather accurate dimensions, though I wonder what the hikers and bikers on the towpath who passed me during the measurements thought I was doing!  The piers are poured concrete, and the horizontal lines that are so visible from afar are actually 1-inch deep grooves that are spaced at exactly 2-foot intervals, making it possible to easily determine the height of the bridge.  The piers seem to have a very slight taper.  A ‘cap’ is present on the top of each pier that looks to be about 1.5 feet thick and that overhangs the pier by about 6 inches in all directions.  The piers are 9-feet thick, and the ends are curved, with the curves beginning 4-feet from the sides.  I contacted Erik  from Ngineer – Erik is a civil engineer in the Netherlands who produces a wealth of 3D-printed N scale structures and details on his Shapeway site that have to be seen to be believed.  I emailed him on a Sunday morning, and by the end of the day we had exchanged multiple messages and photos, and he had produced a pier design and posted it on his Shapeways site (Figure).  The only factor left to determine was how high to make the piers.  I settled on having the piers be 14 rings high, or 28 feet not counting the cap.  I figured that I will need some depth to model the river bed, with the result being that the bridge should have a final height above the water that is similar to what I observed on my recent visit (13.5 rings were visible at the time), which meant that the top to the piers are 28.5 feet above the river.

I ordered 4 of the piers to try things out – I am still mulling over the ideal height.  But, in the meantime, I temporarily attached two plate girders to the bridge, placing them on bridge shoes on one of Erik’s piers – I am quite happy with the result (see Figure).  Also, plans that I have show that the piers are 32° from the perpendicular relative to the tracks so as to face the direction of the river.  Therefore, I will cant Eric’s piers at this angle so as to replicate the prototype.

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It will be a while before I post again – I need to settle on the final bridge height, order more piers (Erik can make modifications in seconds, so it seems!), and then paint and weather everything.  As I am a novice at this, it will take a while, but the net result should be a good representation of the 1931 bridge.  The next steps will be the bridge walkways, and then it will be on to Maryland Heights, the HF tunnel portal, and the C&O canal.

[Bob]

Rats!  I messed the images up .  Here are the other two figures. [ Guests cannot view attachments ]

[Bob]

I am new to this and am clearly confused on how to post multiple images. [ Guests cannot view attachments ]

[Bob]

Here is the last photo. [ Guests cannot view attachments ]

[mu26aeh]

Most excellent !

I noticed your MT ortner hoppers in the photo.  If you're looking for variety in your rock runner, Bone Valley Models has 2 other types of hoppers found in typical rock runner consists.  I have one of each and they are very nicely done.  Some finish sanding is required by will look great when I get a chance to paint/letter them.

https://www.shapeways.com/product/45SPRMBSD/modern-aggregate-hopper-csx-n-1-160?optionId=64771399

https://www.shapeways.com/product/K2ZRWZ72Z/h9-aggregate-hopper-csx-n-1-160?optionId=64766980

[Bob]

Thanks so much!  I just have the 16 CSX Ortner hoppers, and could use some variety.  I'll get a few of these - I had no idea these existed!

Bob

[mu26aeh]

Thanks so much!  I just have the 16 CSX Ortner hoppers, and could use some variety.  I'll get a few of these - I had no idea these existed!

Bob

I have about the same number on my train.  The Hanover Sub hosts a rock runner between Hanover and Baltimore Q762/763 (now W-series train).  I was looking for other cars and found his shop.  He had these listed but not for sale.  I contacted him about them and he had mentioned having to rework some of the dimensions because the print was being rejected.  A couple days later, he emailed saying they were ready to go.  Now I just need to allocate some funds to order more of them.

[Bob]

I should have made the connection!  I have been following your Hannover Sub blog for at least the last two years, and have been really motivated by your scenery, from your rock cuts and trees to the roads and buildings in Spring Grove - really nicely done.  I also have noticed some of your photos show your rock runner, with at least a few different paint schemes.  I shall do my best to emulate you!

[Erik aka Ngineer]

Looking great Bob, I can't wait to see the painted and weathered bridge supports! You provided a great "sunday challenge" and starting with good measurements made a great difference.

[wm3798]

That's going to be a magnificent scene.  I can already see it's got "good bones".  I love the track plan, too.  You're making good use of the Winchester Branch to add some interest without it bogging down your prime objective.

You will face a bit of a challenge with the turnout on the bridge.  My suggestion would be, if you're planning to use it, to mount a tortoise machine below the scenery under the bridge, and extend a fine wire up to the throw bar.  It will be barely visible once you surround it with the scrub trees that are omnipresent along the right of way. 

As I recall, that siding is hardly ever used, occasionally a cut of MOW equipment will be stored there...  You could probably just spike it open to the main and call it Christmas.  Perhaps you could even isolate it electrically and make it your DCC programming track...



As for those Pratt trusses, the Walther's 2-track truss bridge (in the background here) is reasonably suited to the task, although I can't recall the length.  You could modify them to the length you need, and use them as a stand in until something better comes along.


Lee

[Bob]

Hi Lee,

That Walthers bridge looks pretty good in your photo - I did buy a couple of them, and they will be the default choice until something better comes along.  The turnout on the bridge is not wired - as you suggest, I'll just put some MOW stuff (I have only ever seen a hi-rail truck there) there and leave it.  I wasn't clever enough to think of using it as the programming track - that would have been elegant!

Bob

[Bob]

Some progress is being made on 'shaping' Maryland Heights - I am using a Dremel reciprocating saw that I saw on Gary Hinshaw's site - it works very nicely, and leaves Styrofoam chips rather than dust. [ Guests cannot view attachments ] [ Guests cannot view attachments ]

The rest of the bridge piers have arrived for the 1931 bridge - these were designed by Eric of Ngineer.  Now I will need to start painting and weathering these and the bridge plates. [ Guests cannot view attachments ]

[Erik aka Ngineer]

exciting progress! Keep those pictures coming!

[GaryHinshaw]

Harper’s Ferry was my favourite place to visit when we lived in Maryland. You’re capturing the flavour of it perfectly!

[Bob]

Thanks Erick!  I will soon start painting and weathering the bridge components - this is going to take a while, but Lance Mindheim is giving me pointers. 

And Gary, glad you visited HF, and thanks so much for your detailed blog on your Tehachapi BC layout - it is both inspirational and helpful - that Dremel tool you recommend is really great!