Although these tank cars look identical, they are not, and therein lies a lot of operational potential. Looking up the placards, I could see that as a minimum, we have diesel fuel, ethanol, and carbon disulfide. The cars need to be blocked in the yard and spotted at specific locations within the Exxon Mobil complex.
I’ve written frequently about the concept of car spots and the fact that industries that are car spot dependent effectively “stretch” a layout. Food industries are the classic example. Hoppers get spotted in one location, vegetable oil tanks at another, boxcars at still another location. Even a small industry can take a while to switch, and therein lies the fun.
Taking that concept further, the cerebral chess game notches up when you have an industry where all of the cars “look” the same but are not. Corn syrup, for example. That row of seemingly identical tank cars each contains a different grade of product. In order to prevent contamination, each one needs to be spotted at a different unloading pipe. As an operator, you really need to pay attention since you don’t have differing car types to help you tell the cars apart.
On my recent trip to LA to rail fan the Harbor Subdivision, I noticed an unusual amount of activity related to blocking the tank cars in the yard. All were associated with the nearby Exxon Mobil plant. That seemed odd. I “thought” all petroleum tanks were the same. I’ve since learned they are not, which explains the constant sorting and blocking.
Bing Birdseye view of the Exxon Mobil facility served by BNSF’s Harbor Subdivision. From a modeling standpoint, you could probably omit much or all of the complex piping and still maintain the operational play value.
Blog reader, Paul D. works in, and models the oil industry. He was exceedingly kind to take the time to educate us as to what’s going on. Paul writes:
Hey Lance-
I was reading your blog about the Harbor Sub ops and thought I might be able to provide some insight into the XOM operations. I’ve worked in the oil industry for about 12 years now, specifically in oil refining and chemicals manufacturing; I also have a colleague that worked at similar sized lubes blending facility that I mined for information.
At least part of this facility is a lubricants blending plant that likely has some degree of rail service. It’s a little hard to tell but the presence of the larger tanks nearby and the way the piping is routed leads me to believe that this spur may also supply something to the gasoline terminal that’s technically across the street. The number of cars and the amount of switching activity you described seems a bit excessive for the lubes plant only, but could make sense as part of a supply to a gasoline terminal (unless my mental model of the throughput of this lubes plant is way off).
One way to piece this out is if you have any pictures of the DOT hazmat placards on the tank cars bound for XOM – if you see large car blocks of any 1203 (gasoline), 1202 (diesel), or 1987 (ethanol) then they are supplying that terminal through this facility. I’ll drop you some details of rail operations for both so you can pick and choose what you think gives you the most value here and what matches your observations from actually being there – I’ve gone back and forth on whether or not this rail spur serves the fuels terminal, but you should hopefully be able to deduce that from your pictures. Either way, one or both options will give you plenty to work with.
Fuels Terminal:
Most fuels terminals are supplied by pipeline; if they’re getting rail service it’s either because there’s no pipeline and/or they’re getting specialty grades (the refinery I work at in the US makes and ships Canadian grade gasoline via rail, for example) or additives (e.g., ethanol) via rail OR possibly they’re shipping in other biofuels/biodiesel for blending/distribution – again, UN numbers on the DOT placards on the tank cars are you friend here. Regardless of what they’re taking in, it’s likely to be car spot dependent – different gasoline grades may use the same import spot but the cars would all have to be blocked together; if they’re pulling in any combination of ethanol/gasoline/diesel, each of those blocks would have a unique car spot. Guessing most of this would be pre-blocked at the yard, consistent with your observations so some yard sorting possible here if shipments of ethanol, for example, came in via different trains.
Lubricants Plant:
In general, these plants will take in lubricant base stocks (likely from the XOM refinery in Baytown, TX or perhaps purchased from a third party) as well as any additives. It is likely that a decent chunk of the rail traffic into this lubes plant is loaded tank cars with base stocks and then empties out. Most base stocks manufacturers will have a large number of base stocks available; indeed a look at the XOM website indicates many different grades available, ExxonMobil Basestocks & Base Oils. Unloading for different base stocks is likely car spot specific. The overhead shot from google maps at least looks like there are multiple hoses on the ground near the tracks and there are also a LOT of unique tanks, which further suggests a wide variety of feeds/products at this facility; this is not that different from corn syrup in most regards.
Most product is sent out either via bulk truck (note that this location appears to also have a truck rack next to E 37th street) or is packaged and shipped out via trailer. But here’s where it gets a little fun – my buddy told me that some customers were large enough to take rail cars of finished product if they had their own tanks of sufficient size. Another fun wrinkle is that occasionally they would ship interplant to another XOM facility if that facility was having issues and were at risk of shorting a customer. So you could also have some unique product car spots for larger shipments to other facilities as well or one-off variations in the ops.
Overall, a plausible operating scheme for this facility could be:
-Regular/frequent (daily):
-To the lubes plant: Loaded base stocks in, multiple grades (car spot specific); empties out. Multiple cars at a time.
-To the fuels terminal (if rail served from this location): loaded tanks in, gasoline/ethanol/biodiesel depending on what DOT placards you see. One or more blocks of cars for each product type, each block would go to an appropriate unloading spot.
-Intermittent rail service (few times a month?): empty railcars in, loaded finished products out to larger customers (would probably be regular and of the same blends) – probably a car or two at a time, and also car spot dependent as you wouldn’t want to cross contaminate finished product.
-Infrequent/one-off: interplant shipments, could be either intermediates or finished products. Probably one or two cars at a time.
Since everything is car spot dependent, you can still play the same game of ‘car is currently unloading, needs to be pulled out and respotted at the same spot so they can finish,’ and the number/type of car spots you select can be fully dependent on how much space you dedicate to this facility.
Other realistic loads you could add if you felt like a bit of unconfirmed modelers license:
-Solvents or other reagents (things like alcohols, glycols, caustic, acids, other additives) – could be plausible if the plant was equipped to further modify the base stocks or possibly making their own additives on site. Would give you an excuse to break up the parade of 23K & 25K tanks with some 20K or 16K gal cars.
-Equipment via flatcar (mixing vessels, tanks, piping, etc.).
…and in a subsequent email Paul added:
Ethanol and diesel make sense to me – I’d bet those 1202’s are actually biodiesel. They have to rail both to terminals since there’s no pipelines for either of those products and CA has some pretty strict renewable fuels mandates. Looks like the longer cuts for the fuels terminal may go to the rear of the spur, so possible they have to move cars for the lubes plant out of the way to pull/spot for the fuels. Seems like an interesting arrangement to me – if I had to guess, that lubes plant has been there for awhile and at some point in the last 10 – 20 years when the renewable fuels mandates really kicked in, the terminal made an arrangement to use the spur for unloading biofuels. Should make for interesting operations!
Thanks Paul!