Using the Corner

 

Modeling the AT&SF - D&RGW Joint Line through Colorado Springs from Milepost 70 to Milepost 80 circa 1978-1979

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Post 25: Using the Corner

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Although I was pleased when I completed the last bit of mainline benchwork that now connects Kelker-Drennan to the swing gate (see the bottom of Filling in the Gaps), I also couldn't help feeling something was missing here. Frankly, scenically this is the weakest section of the layout. Although the prototype main line does curve through here on its approach to the Santa Fe bridge over Sand Creek, which will be modeled atop the swing gate, on the layout this section is more just a utilitarian connection from A to B, constrained by the available space and track geometry, with the mainline pushed right up against the wall because it has to be. As I said, I will attempt to downplay the main through here by placing a berm and vegetation between it and the Army's line to Fort Carson and live with it.

But that still leaves a fair size empty space to deal with back in the corner at the south end of the Drennan Industrial Park beyond the LPG dealer. I suppose I could have coved the corner here and built up a low bluff with scrub woods to create a scenic transition, but that didn't really feel right for the location, which is more open. In later times a spur track was extended back there to serve Columbine Steel, along with a rather large Strescon precast facility, and the Rock & Rail unit aggregate train operation, but they were all well beyond my modeling era anyway, plus I didn't want to squeeze something into a space that wasn't big enough to fit more than a caricature. Besides, any track extending back into the corner would be a real stretch to reach. No more of that, thanks.

But there was an industry typical of the area that would fit both the place and space quite nicely, even if it was not rail served. As I mentioned in my post on laying out Kelker-Drennan, the industrial park at the south edge of Colorado Springs sits atop a large deposit of alluvial sand and gravel that has been developed by extractive and construction operations. Over time it has been filled up with scrap yards, sand and aggregate pits, concrete batch plants, a precast concrete operation, asphalt plants, and the like.

That last industry would make good use of the empty corner with a business that is typical of the Kelker-Drennan industrial area. In fact, today there are two hot-mix asphalt plants in the neighborhood. Kiewit Western is located diagonally across the mainline from Western Scrap Metal, which is represented on the layout, while Martin Marietta is located just a little bit further south. Both are large current-day operations with modern, high capacity plants and sprawling yards for material piles, yet neither of them justify direct rail service. (Very few asphalt plants do.)

What I envision would be a much smaller operation, however. This quick and dirty low-res Photoshop mock-up will give you some idea of what I was thinking.

I'm not actually positive that there even was an asphalt plant present in my modeling era or not, as there is a gap in my collection of aerial photos and satellite views of the area, but I'm not sure that there wasn't one either. For sure it would not look out of place or time on the layout as asphalt plants are not just widespread, they are downright ubiquitous, since paving asphalt is in demand locally just about everywhere for use as a roadway, parking lot, work area and runway surface, and it all periodically needs to be renewed.

Asphalt plants come in several types and sizes, ranging from small portable drum plants with all components mounted on semi-trailer chassis or skids so that they can easily be relocated from one work site to another as needed, through older batch plants with fixed elevated mixing towers, more modern continuous-production drum plants, right up to really large concerns with multiple mixing plants on the same site, as I learned when I took a deep dive research side trip into asphalt mixing plants.

Oh, oh, there he goes down another distracting rabbit hole when he should be getting on with the real work of putting down track. I won't bore you with my findings on prototype asphalt plants here, but for those who are interested in learning more here are three useful references for further reading with good photos and diagrams:

Asphalt Production, a Power Point slide deck pdf

Hot-Mix Asphalt Plant Operations, an FAA/US Army Corps of Engineers pdf

Energy Efficiency and Cost Saving Opportunities for Asphalt Mixture Production, an Energy Star pdf

You can also check out the websites of some of the asphalt plant manufacturers for high quality photos of their equipment. Some good ones I looked at were Almix, Astec, CWMF, Gencor, and Tarmac International. Most of their products are physically very similar (no doubt they would beg to disagree), with paint scheme and logos being the main visual difference for us modelers.

We'll just look at what I've come up with for a solution on the layout. Those who are only mildly interested can just read on and look at the pictures here.

Below are two typical small, compact counter-flow drum plants with three silos similar to what I'm thinking.

The down on view is neat as it clearly shows a cramped older plant that has been added to over time. Note the original horizontal liquid asphalt storage tank in a concrete containment revetment, and the newer vertical tanks in their own steel revetment. Other views show that it has two original silos with a third added silo of slightly larger diameter. 

And here's a schematic illustration of a typical plant with the major components identified. 

The individual components can be arranged in different layouts to facilitate material flow and space constraints, but a T configuration is common, as seen in the two photos. Add an LPG tank if the plant is fired by gas, or a heavy pipe stand if by LNG.

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Walthers makes a kit for a small asphalt plant with two storage silos. It represents a small and very basic continuous-production, parallel-flow drum hot-mix plant, which have been around since the early 1970s, so it should fit my era.  Figuring it would probably do the trick for what is essentially non-rail scenery, I picked one up. Well, that was the plan anyway.

Now, I give Walthers full credit for developing the "industry suite" concept of model product and marketing, combining a freight car(s), a structure kit(s), and a family of related vehicle, detail and scenery items all geared to modeling an identifiable typical industry. Their Black Gold Asphalt Plant (933-3085) is a case in point. The problem is their structure kits can be hit and miss in terms of execution. Sometimes the need to simplify and compress a large industry into a layout size footprint just stretches plausibility too far—even to the point of caricature. And sometimes the quality just isn't there, with grossly over thick molded parts and details. 

I found that their asphalt plant kit suffers from both problems to some extent. While the bag house and the hot exhaust and dust duct work were perfectly acceptable, I found the steel support structure for the tall storage silos to be grossly rendered, even for background scenery purposes. And the drum mixer-heater was ridiculously under size, tiny even.

Clearly I would not be satisfied building the kit as is, so I looked to see if I could turn this sow's ear into at least a simulated leather purse.

I figure I can use the baghouse and duct work, aggregate feed bins, and conveyors more or less as is, along with the drum support base, trunnion rollers and some other parts. I've already cut some Plastruct 1 1/8 and 1 1/4 inch ABS tubing to fashion a more plausible drum mixer-heater and rings. And I will be modeling a slightly different counter-flow drum with the ducting at the opposite end.

The kit's horizontal insulated warm liquid asphalt storage tank is fine, but I prefer a pair of vertical tanks, which I cut from the same ABS tubing. (The fine-tooth finishing blade on my chop saw worked just fine as long as I didn't bring it down too fast.)

The hot-mix storage silos are another matter. As I said, the kit's steel silo support structure is totally unacceptable, so I purchased the appropriate sizes of Evergreen styrene H and I shapes to scratch build a replacement support structure. The kit's silos themselves are formed of six separate segments that you stack and glue together, which does simulate the insulation jacketing used on some prototype silos, but I want to model a three-silo plant, so rather than buy another kit full of parts that I won't use I cut three identical lengths from a piece of nominal 1 1/4 inch ABS plumbing pipe that I had on hand that turned out to be only .o15" fatter than the stock Walthers parts.

The kit includes an enclosed vertical bucket elevator to charge the silos, but I preferred a more visually interesting enclosed slat conveyor inclined at 45°. The Model Mechanic used to list a 3D printed one on Shapeways, but it should be easy enough to scratch build one from sheet and strip styrene. The kit does not include a truck scale, usually located in the loading lane beneath the silos. It should be easy enough to fabricate one from .060" styrene sheet. Small hopper silos for the collected dust and additives, stairs and catwalks, the gas blower, wiring for the drum motors, and piping for the liquid asphalt will round out the plant.

Most plants are painted utilitarian light grey or tan, but I did find some that were light blue and even black. Perhaps the sharpest looking ones are made by Astec, wearing basic tan with dark chocolate brown lower sections (the better to hide spilled asphalt), with a red-orange separation stripe.

A finer looking support structure, three silos, the sloped conveyor, and a new mixer drum should insure that my model plant will look quite different from the stock Walthers kit.

So how might the plant look in the corner on the layout? Here you go, all mocked up:

In the foreground is the line to Fort Carson. The red & white pickup is crossing the mainline on Las Vegas Street, with the entrance into Summit Asphalt behind it. Maybe put just the front facade of the office right against the wall, or just keep it as is and leave it to the imagination? Does it look cramped and forced to you, or will it look believable, like it fits the location and era, distracting you as the mainline passes out of the scene? 

Let me know what you think.

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