Freight Car Friday – Spine Cars

4 04 2014

Articulated “spine cars” are a common sight on North American mainlines today as they carry trailers and containers in priority intermodal trains. While their use has exploded in recent decades, the history of this “bare bones” car goes back much further.

skeleton car

The skeleton log car was more efficient in mountain operations.

The earliest spine cars weren’t used to haul trailers or containers. In fact, they were about as far from the high-speed freight intermodal market as you could get! Used by logging companies as early as the late Nineteenth Century, the basic spine car offered a vehicle with a minimum light weight and easy unloading of large logs.

Simple to build, these cars were not much more than trucks and a center frame or “spine.” Cross beams over the truck helped support the log loads. Stacked and chained down at the logging camp, once the logs arrived at the mill unloading was a simple matter of unbuckling the chains and tipping or pushing the logs off and into the mill pond.

front runner

The Front Runner took minimal design to the limits – or maybe just a bit too far beyond them. One example was literally plucked from the scrap line for preservation at the Museum of Transportation in St Louis.

Eliminating the cost, weight and maintenance of a flatcar deck made sense in this service. It would be many decades however before the idea found a practical use in common carrier rail lines.

The first uses of spine cars in intermodal service began in the late 1960s with projects like the Clejan car on the New Haven and Southern Pacific and the better-known Flexi-Van cars on the New York Central and several other railroads. Like the logging spine cars, the basic premise behind these designs was to reduce the weight and cost, and inefficiencies of the flatcars currently used in Trailer on Flatcar service.


A 5-unit spine car loaded with 53′ domestic containers is a contemporary staple. This car can also carry trailers.

These pioneering spine cars were similar in length to the longer flatcars then in service for hauling trailers, 75 feet. Of course you couldn’t load these cars the same way you’d load a conventional flatcar, and therein lay the real drawback to the designs. The FlexiVan car used a turntable on the spine to pivot the container load so that no special cranes were needed. But this had its own set of problems from extra maintenance and complexity on the cars to a need for empty chassis at each terminal. For the efficiencies of the cars to be realized, railroads would also have to redesign the terminals and purchase new equipment to load and unload the spines.

As intermodal trains continued to evolve into longer-haul services from fewer dedicated hubs in the 1970s, the climate improved for alternatives to the flatcar and conventional “circus style” loading. In the 1980s, the first new spine car to have a major impact was the “Front Runner” – a single unit car whose construction took minimization to the extreme. The central spine had two platforms attached at one end to support the trailer’s wheels. It rode on two axles with only 28″ wheels to lower the total height. The cars were light – too light – and were prone to derailments, especially when running empty and mixed in with heavier, traditional equipment.

trash spine

Although normally thought of for traditional intermodal containers and trailers, specialized spine cars can be found in waste container service as well.

The advantages of this reduced design were apparent however and railroads, car builders and Trailer Train all partnered to bring new designs to the rails. By the end of the 1980s, the five-unit articulated spine car emerged as the new standard. Articulation allowed use of conventional trucks while further reducing weight and coupler slack in a train. While some early spine cars were trailer only or container only, dual-capacity cars soon emerged for greater flexibility and fleet utilization.

Since then, the overall form of these cars has changed little. The most consistent change was an ever-increasing length of the individual cars to accommodate longer trailers. Today both three and five-unit cars are common. Together with the double-stack container well cars, these platforms form the “backbone” of the North American intermodal fleet.

Freight Car Friday – Bulkhead Flatcars

28 03 2014

Flatcars are one of the most simple freight car designs, but also one of the easiest to adapt to special loads. One of the most common adaptations is the use of fixed ends, or bulkheads, to protect neighboring cars from a load that shifts during transit.

pipe load

Pipe loads clearly show the safety gained by the bulkheads on the ends of the car. Even with the straps and wood blocking, this load could shift in transit.

A large load, like a long train, has a lot of momentum. A quick start or a sudden stop caused by the slack action of the couplers at the end of a long train, an emergency brake application, or just a hard coupling in the yard may be enough to break the tie-down straps and send a flatcar’s load hurtling beyond the end of the car. This is dangerous in any circumstance, but if the flatcar and load are coupled to an occupied locomotive, caboose, or a car filled with hazardous materials the situation can become much worse.

jail cells

In most cases, the loads are limited to the height of the bulkhead, however this pre-made prison cells are an exception. – photo courtesy of Walter A.J. Kuhl.

Today, most railroads place restrictions on where a shiftable load may be placed in the train. But a bulkhead flatcar minimizes these dangers and eliminates this added operating headache.

Despite the fixed ends, the sides of these flatcars remain open to the deck and can otherwise be loaded and unloaded like any other flat. The loads must also be secured to the deck to prevent loss over the car sides. Like most flatcars, most bulkhead flats have rows of stake or tie-down pockets along the sides where these security devices can be attached.

tarped load

Covered loads are not uncommon on bulkhead flatcars. These are easy modeling projects for any layout.

Bulkhead flatcars are used to carry the same loads you would associate with other flatcars as well. Lumber, steel products of all shapes and sizes and large machinery are the most common. As long as the load fits within the length of the car and can be loaded / unloaded from the side, a bulkhead flatcar will serve well. Many loads are covered in tarps or wrapped in plastic for added protection. These “mystery loads” can be easy and enjoyable modeling projects. (See how to make your own in this previous blog.)


In addition to shorter bulkheads, this flatcar has additional fixed stakes to secure rebar loads.

The bulkheads themselves come in many shapes and sizes. The main structural part of most bulkheads is steel. The wall facing the load may be made of steel or wood. With some loads, the bulkheads not only prevent shifting, they help support the stacks themselves such as pulpwood flatcars.

Most common are cars with ends as tall as the typical boxcar. Short and mid-sized bulkheads are also used for loads like steel slabs. These heavy loads fill the car’s weight capacity in only a few feet of vertical height. Lowering the ends reduces the light weight of the car, in turn offering some increased capacity for the load without sacrificing safety.

steel load

This Southern car features a wood deck and bulkhead walls. Plate steel loads are one of the most common found on these cars.

The Erie Lackawanna likely has the record for the lowest bulkheads with fixed bulkheads only 12″ tall! Because the ends were permanently attached, the cars carried the same “FB” designation used by all bulkhead flatcars.

No matter how tall or how small, bulkhead flatcars are an important part of the railroad freight car picture. With loads as diverse as the cars themselves, you never know what you may find.


Freight Car Friday – TOFC Flatcars

7 03 2014

Today’s intermodal equipment takes many forms. For decades however, there was only one standard – the flatcar.

early flat

An early Trailer Train 75′ flatcar is preserved at the Virginia Museum of Transportation with a load of two Sea Land containers on chassis. It is hard to imagine a more perfect car to describe the heritage of the modern railroad era!

The origins of TOFC, or Trailer On FlatCar, service began in the Nineteenth Century. It wasn’t until the mid-1950s however that the service began to grow into the important traffic source we know today. The common term “Piggyback” as applied to this service actually originated with Pullman Standard advertising in 1954.

In the first decades of TOFC, two types of flatcars emerged. New cars dedicated for hauling trailers were built, most to a length of 75′. The cars were long enough to hold a pair of 35′ trailers. While the cars were long compared to conventional freight cars of the era, they were no longer than passenger equipment and few railroads had any issues with interchange of the cars in most traffic corridors.


Lionel’s early TOFC flatcars represent common adaptations made to the PS-4.

By carrying two of what were at the time the largest trailers on the road, the 75′ flatcar offered a more efficient car weight / capacity ratio. And the new dedicated cars were designed for much more efficient loading and unloading, using collapsible “fifth wheel” hitches. The rub rails along the sides of the cars could be used for additional tie-downs and also to help prevent a trailer from being backed over the side when loading.

As the service took off, new cars could not be purchased fast enough. There were also roads that could not afford the new equipment. This led to a movement to convert older, standard designs for TOFC service. Most common were the conversion of 50′ cars which could hold two smaller 25′ trailers or a single larger trailer. While less efficient in service than the modern cars, these were cheaper and faster to put in service and had the advantage of equally quick to convert back into standard flatcars if demands changed again.

The 89' flatcar became an intermodal standard in the 1980s. The ACF-built "F89-J" class cars were some of the most distinctive. A modern 53' trailer creates a loading challenge however.

The 89′ flatcar became an intermodal standard in the 1980s. The ACF-built “F89-J” class cars were some of the most distinctive. A modern 53′ trailer creates a loading challenge however.

The balancing act between efficiency and production costs would continue to define TOFC flatcars over the coming decades. One of the biggest forces driving a constant change in the cars was the trailers themselves. As trailers grew ever larger, the flatcar also had to expand to keep pace. 40′ trailers pushed the development of an 85′ car. No sooner were these starting to be produced than trailers grew to 45′ and the 89′ car became the new standard intermodal flatcar.

The 89′ Flatcar became a versatile platform for many different types of loads. For TOFC service, most could haul a pair of trailers up to 45′ in length each (each overhung the end of the flatcar by a few inches – accommodated by a longer coupler shank.) Others were equipped with hitches for three smaller 28′ “pup” trailers favored by the LTL (Less than Truck Load) and parcel carriers. In addition to trailers, many flats were designed for the option of carrying containers as well. We’ll talk about these in a future blog.

NS flatcar

First built as a boxcar, then converted to a TOFC flatcar, this Norfolk Southern flatcar is in the shops for rebuilding once again into a crane idler car.

During the reign of the 89′ flat, many intermodals switched from the old “circus style” loading to using large cranes or special lifts to load the trailers. The 1980s saw the removal of the bridge plates from the ends of the cars which had allowed the trailers to be moved across the gaps during loading.

While the 89′ flatcar was the most common in this era, shorter “conversions” were also still found. Like the early days, these were done to fill a rapidly growing need at low cost using existing equipment. Most telling were conversions made not from flatcars, but older boxcars. The rise in TOFC traffic was seen as conventional boxcar traffic was in decline. Several railroads sent unused boxcars into their shops, cut them down and converted them into dedicated TOFC flats. To reduce weight further, and with trailers now being loaded by crane, many of these cars only had a partial floor – another sign of changes to come.

Long Runner

One solution to the challenge of growing trailers was the “Long Runner” – a pair of flatcars semi-permanently coupled. Notice how the center trailer spans the gap.

While the railroads enjoyed a fleet of tens of thousands of 89′ flatcars, the trucking company continued to push for even larger trailers. When 48′ and then 53′ trailers arrived on the scene, the utility of the 89′ flatcar had been exceeded. Extending the length of the car was no longer a practical option. Single-trailer loading offered not only a very poor weight efficiency, but add fuel costs as the large open spaces between trucks created additional wind drag.

scrapped flatcars

While many TOFC flatcars were repurposed, like so many important cars in the evolution of railroading, their ultimate fate is here.

In order to extend the life of many flatcars, companies like Trailer Train and Florida East Coast began joining a pair of cars with a drawbar. With a single trailer up to 57′ in length on each, a third could be placed across the gap. Some of Trailer Trains earlier “Long Runner” conversions also required widening the deck and sides to accommodate that center trailer’s bogie as it slid across the deck through curves.

By the early 1990s however, the need for non-conventional equipment for handling trailers had become obvious. Rather than adapting for intermodal use, many 89′ cars were modified for hauling other loads – everything from heavy equipment to pipe, to auto frames and rail. Articulated platforms offered much greater efficiency in operation than the traditional flatcar. While you will still see one occasionally in an intermodal train, the presence of a true flatcar is becoming quite a rarity.

Freight Car Friday – Extreme Flatcars

1 11 2013

The word “extreme” today is often used as a catchphrase for anything even slightly better than average. Not so here with these flatcars. Some of the specially designed cars on today’s railroads are unbelievably big and complex. They may in fact be too big for words. But if not, we’ll settle for “extreme!”

kwux 101

KWUX 101 – owned by Siemens – rides on four six and four four-axle trucks and stretches for just over 119 feet between the couplers! The deck of this car can be removed allowing it to transport even larger loads like a Schnabel car.

What sets these cars apart from the rest? For one thing, capacity. Some of the cars seen here may carry loads approaching one million pounds in weight. Think of a Pennsylvania Railroad M1. Now picture a car strong enough to carry two of them with nearly 100 tons of capacity to spare. By any standard, that is impressive.

Although they still have a flat deck to carry the load, these cars share little else in common with a traditional flatcar. In fact, the light weight alone of some of these large cars is greater than the capacity of many standard freight cars. Supporting all of that weight requires a lot of wheels, bolsters and engineering.

KWUX 200

KWUX 200 is fresh from the Kasgro shops. In addition to carrying up to 955,000 pounds, this car can lift the load to clear obstacles.

For the ultimate in flatcar technology, consider KWUX 200 built in 2013 by Kasgro Rail in New Castle, Pennsylvania. Not only can the car support a 477.5 ton payload, it is equipped with hydraulic pistons which can raise the car deck up to an additional 24 inches and move it 14 inches side-to-side to help clear obstacles along the right-of-way! This can be a huge help when navigating curves. A load this large can make even the prototype’s curvature feel like O-27.

Although this car appears to have a “depressed center” design. Thanks to the thickness of the 40 foot deck, the load is still higher above the rail than most conventional cars. The tall towers on either side help sling the weight onto the sets of trucks while keeping the center of gravity as low as possible. The trucks themselves are connected in pairs with special span bolsters. These bolsters are then connected to each other and finally to the sloping supports for the flatcar deck. This articulation gives the car both the necessary weight distribution and agility to navigate curves.

What Do They Carry?

DODX flat

Looking small in comparison to the cars above, this brand new 12-axle flatcar is being built for the Department of Defense for a variety of heavy loads.

The largest of these cars are designed for heavy power assemblies including transformers and turbines. The largest cars may make only a few trips a year – or less – but they are the only practical way to transport these loads. And a single trip or two may cover the cost of the car’s construction.

The Department of Defense is another large user of heavy-duty flatcars including both depressed-center and straight deck designs. These can be used for a variety of special loads from heavy machinery to radioactive material casks.

With their infrequent use many of these cars can stay in service for decades. The cars are also frequently modified, particularly the decks, to safely secure each unique load. It is not uncommon for newer cars to reuse rebuilt trucks from earlier heavy flatcars as well.

Special Moves


To keep watch over the special loads, many large flatcars travel with a dedicated caboose – an added bonus for modelers!

Even when empty, these large cars often require special handling. If handled in general freight they are usually placed at the very front or rear of the consist. Loaded cars however can often require a train of their own. Not only are they big and heavy, these loads must often travel at very reduced speed and stay clear of other traffic on the line.

In a dedicated train, it is not uncommon to see empty idler cars placed between the heavy flatcar and locomotives for added protection on bridges. Flatcars and gondolas are most common so that the crew will still have an unobstructed view back to the load.

Cabooses are also still common as a rider car to accompany these special moves. The railroad may provide the caboose (or an extra caboose in the days when there was still a train crew to accommodate at the rear of the train.) Today, the rider caboose is often supplied by the same company as the flatcar. the two cars will stay together – even on the empty return trip.