Good progress on the block between West 26th and 27th Street along Tenth Avenue forced me to finally think about the elevated section of my layout. With some of the sections of the track leading through already built structure, I also had set a few parameters. Height above surface would be about 42 mm and the two tracks would be about 34 mm apart. Openings would be big enough for larger box cars like a 50′ PRR X58, but not for hi-cube boxcars.
While the street-level track is all hand-laid with code 40 rail, I intended using code 55 manufacturer-built tracks. That would include ready to use turnouts from Atlas. I plan to mostly use code 55 Micro Engineering flex track and even some Atlas sectional track where appropriate. I set the maximum depth of my shelf layout to about 28″ which would give me a minimum radius of 12.5″ for the reverse loop. This was all good but I finally had to come up with a proper design.
Comprehending the New York Central Westside Railroad south of 32nd Street as some tracks over a sequence of bridges would not do justice to its unique design. Look at what the railroad has built over Tenth Avenue between West 17th and 14th Street, for instance. We see a dual track mainline, a siding and freight spurs all built on a massive elevated platform. There is a similar construction above West 30th Street where a branch of the freight line traverses Tenth Avenue. The real estate used for the bridge in both cases considerably exceeds the space needed for the tracks. The obtuse angle at which the tracks cross Tenth Avenue explain some of the excessive size. In addition, the High Line has a very uniform appearance and its constructions appeal visually.
450 West 14th Street
The few but very pervasive design elements are:
- The deck of the elevated platform rests on longitudinal plate girders and system of crosswise braces.
- The bridge sections do not have abutments. Instead, columns support the deck at regular intervals.
- Some of the buildings with which the High Line integrate function as abutments. Examples are the former Nabisco building between West 15th and 16th Street or 450 West 14th Street (photo).
- The supporting structure appears to be very modular.
- Two basic types of parapets exist. The predominant type along Tenth Avenue uses riveted vertical steel plates and a massive railing on top of the plate girders. This very sophisticated type of construction looks heavy and overwhelming but still esthetically pleasing.
- A second less sophisticated type uses simple concrete elements combined with more traditional tubular steel railings as parapets.
This simple set of rules provided enough guidance for me for designing and building the first section of the High Line.
To start, I designed a modular grid of girders with integrated supporting columns. I used 1/16″ MDF snd design them so they would interlock. A two layer deck of the same material glued on top gives the MDF deck more strength. I also provided tabs for a third layer to close the underside of the girder grid. This construction provides a very strong core. I created two variants of this basic design. One for the straight dual track bridges and a second one for the curved single track sections. I designed the transitions such that individual sections can connect easily. The ones for the straight track allowed flexibility in vertical movement to adjust for different elevations. The second one for curved tracks allowed for a variable angle of the curvature.
To create prototypically correct models, I added plate girders from Micro Engineering on the outside of the substructure. I chose 80″ girders for the more massive straight bridges and the smaller 40′ version for the curved sections. I just glued them on to the MDF girders using CA super glue. For the sophisticated railing I had to be a bit more creative. Again, scratch designing and building was the only viable approach with no manufactured product available.
At first, the sophisticated, decorative design of the bridge parapet and the railing on top presents a challenge. 3-D designing and printing would be an obvious option. I figured out that I also could emulate the complex work of riveted plates that make the parapet by decomposing it into layers and overlaying them. I’d lose the rivets but that’s a not a big loss in N scale since they’d be hardly visible anyway. Cutting them in three layers of 0.015″ lazerboard and adding a handrail on top gave me a very prototypically looking and robust enough component. I’d wait gluing it to the bridge until I had laid the track, ballasted it and painted everything, though.
Meanwhile, I made good progress as the entire structure took shape and began looking like a stranded aircraft carrier (left photo above). It now provided the stable platform I needed to lay track. The section includes both turnouts for the reverse loop, plus a third one for a siding or stub track into a building. I used some Atlas sectional Code 55 track to get the correct curve geometry but otherwise I complemented the trackwork with Micro Engineering Code 55 flex track.
Before gluing down the track I had to make a decision on how to ballast the track. While some photos clearly show that the tracks were laid on ballast, other photos suggest that some sections were laid on the bare concrete. Most likely ballast was always used on the dual track mainline but not on the stub tracks into buildings. To get a slightly elevated track level I laid the track on 1/16″ cork mat which I cut carefully to size, glued it down and then sanded the edges.
For the ballast I used a mix of Kaibab Limestone and light gray base powder from AZ Rock to tone down the color. I also added a little bit of Woodland Scenics light gray fine gravel to give it a little bit grainier texture. My first attempt to ballast the edges of the cork bed looked poor as the ballast ran all over the place when I (carefully) wetted it with Isopropyl alcohol and thinned Mod Podge. To get a more regular gradient of the ballast I placed the bridge columns on a piece of 1×2 on one side. The alcohol and glue mix would now wet the ballast evenly and it would stay in place.
The result made me finally happy with a pretty consistent gradient and a much more straight ballast boundary on the concrete. I was still unhappy with the color of my ballast mix, though. To correct it, I airbrushed it lightly with a light gray until I had the desired uniformity and tone. I also applied a bit of Burnt Siena over the tracks plus some dark grey in the center of the tracks.
To finish the bridge I still had to produce the railing, paint and glue it. I needed more than 2 ft of that for the less than one foot long bridge. Even though the railing has a modular structure, I could easily adjust it to the shape of the bridge so that I didn’t have to cut a piece in half in the middle of two posts. Most of the High Line has been repainted then it was converted into a park some ten years ago. On many photos, the paint looks very dark, often too dark to make out details. I decided to use a light gray mixed with matte aluminum metal color from Vallejo to give it a metallic touch. The lighter gray would make it easier
I also had to build the switch machines under the bridge for the three turnouts. I’ll cover this is a separate blog. For now, my first bridge of the High Line is complete and it looks pretty good. To me it looks sufficiently prototypical and aesthetically appealing, just like the real one from the New York Central Railroad.