Colorado Unit Coal Trains 2000-Present
Copyright 2010

Unit Coal Train Frequently Asked Questions
Question: What is a unit coal train?
Answer: The definition I am using is any coal train where the entire train is consigned to one utility and one destination. Unit coal trains originate at a coal mine and travel to their assigned power plant destination without interchanging railcars anywhere along the way.

Question: Why don't you include railroad-owned railcars in your table?
Answer: Because they're harder to trace to a certain utility and in general their car fleets are more complicated. This is especially true of the UP, who still routinely runs trains of 1970s-era steel hoppers from predecessor railroads like CNW, DRGW, and MP. Tracking all the railroad-owned cars would almost require a whole separate web site - and I just don't have the time for that. If some other ambitious soul out there wants to take on that task, go right ahead!

Question: How long are unit coal trains?
Answer: This depends on the route and is generally limited by grades and siding lengths. On the Colorado Joint Line and BNSF's Brush Subdivision, coal trains can be up to 130 cars in length. For the UP lines in Colorado, typical train lengths are between 100 and 110 cars on the Moffat Route and 115 to120 cars on other routes.

Question: How many spare cars will an owner need?
Answer: It is prudent practice to keep 5 to 10 spare railcars on hand per trainset to account for bad-order cars and inevitable casualties. So if you're a utility and you plan on running 125-car trains, you'll probably order 135-car trainsets so that you have 10 spares available per trainset. This might sound shocking, but 10 spares will likely be consumed within 10 years due to wreck casualties. A large part of this high casualty rate is the fact that aluminum-bodied railcars don't hold up very well in wrecks and are usually totaled on site. So, one or two derailments of a single trainset will easily wipe out several cars per incident - in some severe cases possibly even 12 to 15 cars at once! So if you're a utility, what do you do when all your spare railcars are used up and your unit trains are short? The usual course of action is to lease replacement cars. This is why you see random lease cars mixed into utility trains. The other option is to purchase more new railcars, but in small lots that tends to be expensive. So most owners prefer to lease extra cars until they need 50 (or more!) cars, at which time it becomes cost effective to purchase a batch of new cars.

Question: What is the capacity of a unit coal train?
Answer: This depends on the capacity of the railcars used and the length of the train. In the 1970s, 100-car unit trains carrying 100 tons per car carried 10,000 tons per train. Nowadays, 120-car trains are normal with each car carrying roughly 120 tons. Thus the capacity of a modern unit coal train is around 15,000 tons per train.

Question: How much coal does a power plant consume?
Answer: This depends on the size of the boilers, efficiency of the plant, and how often the plant operates at its maximum burn rate. A small coal-fired power plant might only consume 900 tons per day, whereas a very large facility with multiple boilers could consume up to 14,000 tons per day. Compare that to the capacity of a typical unit train and you can see why some power plants only need one coal train delivery per week while other large plants need a coal train delivery daily.

Question: What are you using as the definition of a "Utility?"
Answer:  I am broadly classifying all commercial power generation companies as "utilities". This includes regulated utilities, non-regulated utilities, electric cooperatives, wholesale generators, and independent power producers. The exceptions are industrial coal users, such as industrial cogeneration plants or those using the coal purely for steam generation (to support a chemical process) rather than electricity generation.

Question: What is a "Coal Supplier?"
Answer: These organizations act as coal brokers for utilities. They negotiate coal supply contracts with the utilities, then they negotiate with mines to fulfill these contracts. This is more common with smaller utilties such as electric cooperatives. Large multi-state utilities will generally negotiate their own coal supply contracts directly with the mining companies.

Question: Do power plants have to always purchase coal from the same mine(s)?
Answer: Not necessarily - but typically they do have to purchase a certain grade of coal which may limit the number of mines capable of providing their required grade. Contrary to popular belief, all coal is not created equal. Each power plant is designed to burn a certain type of coal with a certain BTU content, a certain ash content, a certain sulphur content, and so on. Boilers, burners, ash handling equipment, and emissions equipment are all designed for specific coal properties. Changing the coal properties usually requires modification of the power plant, so utilities don't like to change coal grades unless there is a substantial incentive.

Question: What is a "Test Burn?"
Answer: A test burn is when a power plant tries a different grade of coal, oftentimes from a different geologic region. Sometimes power plants will modify their boilers and pollution control equipment to accomodate varying grades of coal and they will use test burns to see how the new coal type affects performance and emissions. Most test burns start with a blend of the test coal combined with the existing coal in order to check the effects of the new test coal. If the results are satisfactory, the plant may switch to burn 100% of the test coal. Test burns may be for short periods of time (i.e. just a few trainloads) or for the duration of several months. In Colorado it is not uncommon to see occasional "test burn" trains originating in Utah or Colorado heading to eastern utilities seeking to try western coal (which is more favorable for emissions).

Question: How far away is Colorado coal shipped?
Answer: Check out the destinations in the table of coal trains originating in Colorado.

Email Me

Last Updated: 03/20/10

Back to the Colorado Unit Coal Trains Home Page

Click here to go to the Coal Car Data Table