American railroads have a rich history of demanding from builders (or cobbling together themselves) locomotive designs tailored to their specific individual needs or just going on a limb and trying something new. This list is by no means exhaustive or the most unique and rare locomotives out there, but it is fairly representative of these creations. Unfortunately, since many of these designs were either homebuilt or built by long-defunct companies information can be scarce. Without further ado, let’s get started:
#1 – Ingalls Shipbuilding 4-S
Model of the Ingalls 4-S. Note the raised “turret cab” and the small switching cab at the rear.
In the mid 1940s, with the end of World War II looming on the horizon, Pascagoula, Missisisppi-based Ingalls Shipbuilding started looking for new revenue streams to help stem the loss it would suffer after winding down warship production. The post-war market for diesel engines was expected to be booming (due to government bans on their production during the war) and Ingalls decided to take a chance.
Out of several proposed designs, the 4-S was the only one actually produced. It was based around a marine 1,650 HP diesel engine and featured a “turret cab” design that gave crews better visibility when operating backwards. It also had a small rear cab with controls for yard switching work. The prototype and only 4-S ever built was ready for work in March 1946.
Several Southern railroads tested out the 4-S but none of them were interested enough to place an order, especially with a company completely new to the field with an unproven design. Eventually, the Gulf Mobile and Ohio Railroad in next-door Mobile, Alabama bought the engine for $140,000 ($1.7 million in 2014 dollars) as a favor to its major customer. Disappointed by the lack of interest, Ingalls never again tried to build locomotives.
The GM&O ran the 4-S for over 20 years and former crews say it earned a reputation for reliability and toughness. It once derailed upside down in Houston, Mississippi and was patched up and quickly returned to service. After a long career, it was traded in by the GM&O as a down payment for a new locomotive. The 4-S was offered to a railroad museum who, unfortunately, couldn’t afford the asking price and it was later broken up for scrap in 1967.
#2 – Krauss-Maffei ML-4000 Diesel-Hydraulic
The Niles Canyon Railway is restoring the only remaining ML 4000 to active service
In the late 1950s American freight trains were getting longer and heaver, but diesel locomotive design wasn’t keeping pace. The Southern Pacific railroad found that it was taking sometimes 10 locomotives just to pull a freight train. After a lot of research, it made a shocking move and turned to Germany to bring an experimental new locomotive design to the United States: diesel-hydraulics.
Instead of the diesel engines providing electricity to power electric motors in the wheels, diesel-hydraulic engines were connected by drive shafts directly to the wheels of the locomotive, like in a car or truck. Germany had pioneered these designs and was considered an expert in their use. Industrial conglomerate Krauss-Maffei designed the ML-4000 specifically for the United States with two Maybach 1,750 HP engines (double the horsepower of any comparable American locomotive) and shipped 21 of them overseas in 1961, all of them eventually ending up in service with Southern Pacific.
The units performed their job well, but it was found that diesel-hydraulics are more suited to lower speed work like switching in a railyard rather than high-speed heavy freight hauling. Once American designs started to sport more horsepower in the late 1960s, SP decided to start retiring the ML-4000s and by 1968, after only 8 years of service, all of them had been removed from active duty and all except 1 had been scrapped.
SP’s homemade “Camera Car” for making training films.
The surviving ML-4000 (#9010) had an interesting later career and is a unique locomotive in and of itself. SP renumbered it #8799 and transformed their expensive German toy into a “camera car”, disabling its engines and cutting off its nose to install a compartment to house a camera and film crew to record training films for rail crews. A second locomotive would push the “camera car” around the SP network filming scenarios to be used in a locomotive simulator, much like some of the older car simulators you might have used in driver’s ed. The last ML-4000 served in this capacity until 1984 when it was finally retired for good and donated to a California museum. It sat outside for many years heavily vandalized and continued to deteriorate until the Niles Canyon Railway acquired it in the late 2000s and started a full restoration. The original nose, destroyed by the “camera car” conversion, had to be rebuilt from scratch and many of the parts needed for the restoration that can’t be scrounged up in Europe are having to be handmade or custom ordered stateside.
#3 – GM LWT-12 “Aerotrain”
The Aerotrain obviously takes cues from auto design.
The Aerotrain takes the cake for many railfans when it comes to strange trains. A creation of General Motors in 1955, the Aerotrain was intended as a low-cost, high-speed train that would capitalize on GM’s automotive technology to lower costs and allow railroads to offer passenger service as cheap as bus fares. Ultimately, they never lived up to their hype and were only used for any length of time by one railroad as commuter trains.
If this coach looks suspiciously like a Greyhound bus, that’s because it is
In fact, through a strange and ultimately poor choice of design, the Aerotrain’s passenger coaches were literally GM highway buses modified and bolted onto a frame with train car bogies. The plan was that once the bus body got old and wore out, you could scrap it and strap down a newer one (also made from whatever GM’s current highway bus happened to be) to the bogies for a fraction of the cost of building a new passenger coach. Even the suspension on the coaches was styled on air-cushions after highway vehicles.
The rear of the train also looked like a car
Starting in 1956, the Aerotrains made test runs with several railroads where their performance was found to be lacking – for example the design was so underpowered that both the Santa Fe and the Union Pacific had to attach helper engines to push it over mountain ranges in California. Passengers on all the railroads complained of the rough ride quality and loud noise at high speeds, mostly stemming from the air cushion suspension not being suited for railroad use. Maintenance on the locomotives was also a nightmare, with even routine jobs being extremely time consuming.
Aerotrain #3 on display at the National Transportation Museum
The Aerotrains did eventually find a home, though, as low-speed commuter trains in the Chicago area for the Rock Island Railroad starting in 1958, but only for a short while. In 1966, much to the delight of local passengers I’m sure, Rock Island decided to do away with the finicky trains. Their career had barely spanned 10 years.
Two of the three trains produced still survive today, but neither of them are complete train-sets. Aerotrain #1 was scrapped by the Rock Island in 1965. Locomotive #2 is preserved at the National Railway Museum in Green Bay, Wisconsin and locomotive #3 is on static display with a few of its coaches at the National Museum of Transportation in St Louis, Missouri.
Walt Disney operating the Disneyland “Aerotrain”
Now, interestingly, for such a weird and failed design the Aerotrain seems to have captured the imaginations of quite a few Americans. There were many miniature scale replicas made of it, including one by lifelong train-nut Walt Disney. The Disneyland Aerotrain had a short career like its larger brother, only running for 1 year before being demolished to make room for the more-famous monorail system.
The Washington Park Zoo “Zooliner”
The most famous replica is at the Washington Park Zoo in Portland, Oregon and is arguably the most successful Aerotrain – it has been in continuous service for over 50 years and remains a popular attraction at the zoo, despite most of its riders not even being born the last time an actual Aerotrain took to the rails.
Other replica Aerotrains in active service are at Idlewild Park in Reno, Nevada and the Ellis Railroad in Ellis, Kansas. There is also one on static display at a hotel lobby in Akron, Ohio.
#4 Booster Units with Cabs
A typical Booster Unit, known as a B-Unit.
This next entry is shared between two separate approaches to the same concept: placing a cab on a booster unit to get a cheap locomotive in a pinch. For the non-railfans out there wondering what a booster unit is a little back story is in order.
In the early days of diesel power a single locomotive often wasn’t strong enough to pull a train by itself. Despite the fact that technology existed to operate multiple units from the lead engine, unions at the time were adamant that a full train crew needed to be placed in every single locomotive on a train. Railroads started purchasing so-called booster units, which were basically just locomotives without a cab installed, as a way to get around this hurdle. A side benefit was that without cabs, control stands or other crew amenities, B-units were slightly cheaper to buy. However, this was offset by their lack of flexibility – a B-unit had to have a cab unit (accordingly called an A-unit) to operate. Eventually, the unions eased up and railroads moved beyond the concept of B-units, preferring to have full cabs on all locomotives so they could be moved around as needed.
-Chicago and Northwestern “Crandall Cab”
CNW’s solution to a locomotive shortage – cobble one together
In the early 1970s, the Chicago and Northwestern Railway was in need of cheap locomotives for its money-draining Chicago-area commuter trains (it was not allowed by the government to discontinue passenger service). Amtrak had just been formed by Congress and had inherited a vast amount of engines and cars from other railroads eager to ditch their passenger operations. Amtrak leadership decided they didn’t need the old B-units and sold them off for a steep discount. CNW’s Assistant Superintendent of Motive Power, M.H. Crandall, saw the solution his railroad needed and devised a scheme to purchase some of these surplus boosters and build a cab and controls on one end to use them for commuter trains.
Starting in 1973, The Chicago and Northwestern built 11 of these locomotives and placed them into active service, running them until the government took over commuter operations in 1977. They were repainted into transit authority colors and run for another decade, with the final two Crandalls being retired in 1989. Unfortunately, none of units were saved from the scrapper’s torch.
Interesting to note is that the term “Crandall Cab” is entirely an invention of railfans – the railroads officially referred to these units as standard B-units despite their modifications.
– Rock Island AB6
Rock Island asked EMD to specially make their B-unit locomotives
In 1939 the Rock Island Railroad started the “Rocky Mountain Rocket” passenger service between Chicago and Colorado. At the town of Limon, Colorado the train was split in two and one part of the train would continue to Denver and the other part to Colorado Springs. Rock Island wanted a small, cheap locomotive that looked like a streamlined passenger coach to place on the end of the train and carry the smaller 3-car Colorado Springs section of the train. This would preserve the smooth, streamlined appearance instead of breaking it up like having a second normal-looking locomotive in the middle of the train would.
The Rock turned to locomotive manufacturer Electro-Motive Diesel to custom-build two of these special units out of B-units straight from the factory. EMD took a B-unit and replaced the two standard diesel engines with one much smaller 1,000 HP engine and used the second engine compartment for storing baggage. It placed a cab and controls with a flat nose on one end and a central door so that passengers and crew could continue to walk through the train to the other passenger cars. They were delivered to the Rock Island in 1940, before the US entered WWII and diesel locomotive production was placed on hold.
Rock Island AB6 in Chicago commuter service
Over time as the Rocky Mountain Rocket got more popular, more power was needed to haul the extra cars and passengers and eventually outmatched the little AB6’s. In 1965, The Rock put standard locomotives on the train and the two AB6s, which had already seen 25 years of service by this point, were re-assigned to Chicago commuter service. They excelled in this role and continued on until they were finally retired and, sadly, scrapped in 1974 after 34 years of heavy use.
It is probably safe to assume that Mr. Crandall at Rock Island’s rival railroad Chicago & Northwestern got his idea for turning b-units into “Crandall Cabs” from seeing the success of their AB6’s.
(More coming soon in Part 2)