Could someone point me in the right direction of what type of cars would be used for unit trains of crushed rock in, say the late 1980s - early 1990s?
Locale would be Central Texas and it would be for a freelanced Class 1 bridge line, comparable in size to the DT&I.
Also, thoughts on typical motive power for the rock trains? So far, I’ve planned that the railroad has typically been a 4-axle road (big buyer of GP30s and GP40s in the 1960s, and then GP40-2s over the next decade), except for a few SD40-2s built to Burlington Northern specs for pool power on coal trains destined for power plants along my line. But what would’ve been typical for rock trains in this time period?
The SP had 3 basic types of equipment for their Texas rock trains, gons (52 or 65’ ft mill gons), OJ’s (the PRR style solid bottom gon ore jennies) and hoppers (100 ton twin hoppers). The MP had 52 or 65 ft solid bottom mill gons or 100 ton quad hoppers. The GRR, WRRC and mining companies tended to have Ortner hoppers (those with the straight ends and “porches” on both ends).
Generally GP’s were used The MP tended to use GP38-2’s and B23-7’s, sometimes B30-7’s. The SP used 4 axle power. The really odd balls were during the CNW merger, the UP had a power crunch and leased anything they could find, they ended up using AMTK F40’s on south Texas rock trains. Mostly because they weren’t good for anything else.
I worked on the MP in Texas in the early 1980’s and the dispatch offices that handled Texas at various times over the next couple decades.
I am most familiar with the SP’s operations serving mines at Knippa, and Blewett on the Sunset route west of San Antonio and, Beckmann on what is left of the Kerrville Branch, northwest of San Antonio, 1978-1986. Since then another quarry has opened at Dunlay, between Hondo and LaCoste TX, but that was a UP thing of the 2000s, so disregard it if you are searching these locations on Google Earth.
To better understand SP’s car utilization, you will find SP freight cars are covered by type, class, and number block-your choice, on Lee Gatreaux’ (I hope the spelling is correct) SP freight car website at www.railgoat.railfan.net . Lee’s site can also be accessed from the Southern Pacific Historical & Technical Association’s www.sphts.org. Click on “resources” and then “links” to members websites.
By the 1980s, SP had standardized their aggregate cars on 100 ton capacity units in the gondola and hopper types. This is not to say a 70 ton car didn’t show up occasionally, but it was to be avoided as much as possible due to the likelihood of it winding up overloaded. Envision a guy who has been loading 100 ton cars all day, everyday in 100 degree weather for the past month and the 61st car in that 84 car string is only a 70 tonner. Oops! Thats why SP restricted aggregate service cars to the 100 tonners.
Like most railroads, SP had their own internal classification system for their locomotives and cars. The first letter defined the car type. In the case of the aggregate cars, this would be “G” for gondolas and, “H” for hopper cars. The letter would be followed by a two or three digit number indicating capacity in tons. Another number followed the capacity, indicating the numerical sequence of that group
As NHTX wrote the choice of equipment depended on how it was going to be unloaded.
Hoppers were generally unloaded over a pit, which means a permanent structure. Many of these facilities served ready mix concrete plants and were in locations where there were steady demand for aggregate.
Gons and OJ’s were used where the cars were going to be unloaded with a backhoe, either one that crawled across the tops of the cars or was along side the track. Often they served locations that were dedicated to a specific project. Often that was a highway project that might take dozens of trains, but was only going to last 4 or 5 years, so they didn’t build a permanent unloading pit. When they built the railroad at Spring, TX in the early 1980’s they recieved dozens of rock trains in gons, all of which were unloaded by backhoe.
There were two types of backhoe used. There was a smaller type that was a backhoe.front end loader wheeled tractor with the outriggers and bucket modified to rest on the top chords of the car sides. The other was a tracked backhoe that would just crawl over the loads, unloading behind it.
In both styles it was common to unload down to the last part of the last car. They would leave the car with the backhoe in the unloading facility and then when the new train arrived, they would put the loaded cars on top of the backhoe car and the backhoe would work its way down the line of cars, once again stopping at the last car. This process was used for projects that got a lot of cars frequently. It saved the time and trouble of getting the backhoe on and off of the cars. The rock trains ran on a semi-regular cycle. They often didn’t work on weekends or if it rained (the quarry pits would get too muddy).
Sorta. The SP 33xxx series cars were restricted to 40 mph as were the Herzog rock cars. Any empties other than those listed in the special instructions in any train were restricted to 55 mph. Plus it wasn’t uncommon at various times for the railroads to put a blanket 50 mph speed restriction on everything except passenger, intermodal and auto trains for fuel conservation. Yes the max speed was 70 in places, but the majority of trains weren’t going 70.