Dating via the Details: General Car Design

Here we must necessarily deal with generalities rather than specifics, but even if you’re not too particular about making sure every car is totally appropriate for a specific year, you can help create the impression of a general time frame by at least choosing appropriate rolling stock. To get fully accurate by era equipment, research on the specific car(s) on an individual or series basis would be required, to determine if the specific railroad paint scheme is era-appropriate (e.g. a 1970s car but with a 1990s repaint), or if a particular car or series hadn’t been sold off (or conversely, acquired from a secondhand source) by a certain date, or whether a model is even accurate in the first place for a particular railway, but this should at least give an “at a glance” view of the evolution of the North American freight car fleet, although by necessity not every detail can be covered.

Car Designs and Sizes

Some interesting dates for the introduction of certain types of cars:

1948 – mechanical refrigerators placed in service by FGE

1955 – Airslide covered hopper introduced

1959 – 85′ flatcars with kingpins (TOFC) introduced

1960 – trilevel autoracks introduced

1967 – Thrall introduces all door boxcar

1973 – first enclosed trilevel autoracks

60 and 86 foot “high cube” boxcars were built for specialized services (primarily auto parts – especially bulky steel body panels from centralized stamping plants to assembly plants) in the 1960s and 1970s.

AAR “Clearance Plates” are clearance diagrams that show the maximum external dimensions for railway equipment in order to stay within standard clearances. Larger standard “plates” have been added over the years:

1948 – Plate B adopted, max height 15’1″

1963 – Plate C adopted, max. height 15’6″

1974 – Plate E adopted, max. height 15’9″

1974 – Plate G adopted, max. height 17’0″

1975 – Plate H adopted, max. height 20’2″

(Of course the clearance plate is full cross-sectional profile, not just a max. height – the outline of the common NMRA standards gauge is basically the Plate H clearance diagram.)

Most 50′ boxcars built up to the early 1970s fit the Plate B clearance (although a lot of Plate C cars were built in the 1960s – especially Canadian newsprint service boxcars). By the mid 1970s Plate C was standard and Plate B boxcars were essentially no longer built. (While early RailBox cars were Plate B, the common picture people have of the standard “RailBox” style boxcar is a late 1970s, exterior-post construction Plate C boxcar.) As of the 2000s, pretty much all new boxcar construction (and yes, new boxcars are still being built by the thousands every year) are 50′ single door or 60′ double door Plate G high-cube designs.

Service Life

Much of the information above deals with the introduction of car types and designs; but an individual car can last in service for decades.

For cars built before July 1974, service life in interchange service is limited to 40 years.

For cars built after July 1974 service life in interchange service is 50 years, although this can be extended to 65 years with a rebuild or mechanical certification (some groups of TTX autorack flatcars have received a blanket certification for 65 years service).


The earliest freight cars were built entirely from wood. Sometime around 1910 car builders started moving to steel under frames (but still using wood or mostly wood bodies) for most types of freight cars such as boxcars, flatcars, etc. Most hopper and tank cars were all-steel construction by this point however.

By 1928 wooden main sill underframes were banned from interchange. Truss rod reinforced underframes (new or retrofitted) were still legal until 1940 when all wood underframes were outlawed from interchange service.

Dating via the Details: Wheels, Running Boards and Ladders

In a previous post, we looked at data, stencils and lettering that can update or firmly root a car’s appearance to a 1970s or newer time frame. Here we’ll look at some of the concurrent physical changes to freight car hardware (and rules regarding the same) that will also help indicate the modeled time frame.

Running Boards, Ladders, and Handbrakes

Model of a modern (1974-built) boxcar built with low ladders and no running boards (roofwalk). The “ribbed” outside-post construction of this car is also a post-1960s signature.

The earliest railroad boxcars featured handbrakes that were operated via means of a wheel attached to a vertically-mounted brake staff that would be operated by a brakeman walking on wooden running boards down the centre of the car’s roof.

While automatic air brake technology was introduced and improved during the late 1800s, this arrangement stuck around, with the handbrake to tie down a parked car still located at the top of the car end, and running boards (later made of steel instead of wood) to allow brakemen to move down a cut of cars to set (or release) multiple hand brakes.

The first major change in rules regarding running boards came in 1945 when wood walkways outlawed on new cars. New cars were to feature expanded metal running boards, but the wood walkways were generally not replaced on older cars. (Obviously metal running boards would have existed before this but I don’t have any “first” dates of adoption.)

The most significant change came in 1966 when the rules were changed to no longer require running boards. New cars ordered after 4/66 or delivered after 10/66 were required to be built without running boards and low-mounted handbrakes. Running boards also began to be removed from cars, with the original target date for completion being 1974, but full compliance lagged behind a bit. By 1982 walkways were banned on boxcars and reefers in interchange service in the US.

Older 1940s built boxcar that has been upgraded and modernized to remove running boards (although the former supports are very much in evidence) and cut down ladders. On this car the brake gear has also been lowered, however on many cars the brake wheel was left in its original position, with full height ladders remaining on the “B” end corners to reach the handbrake.


Journal Bearings

50 ton truck with plain bearings (left) vs modern 100 ton truck with roller bearings (right)

Railroad car axle bearings came in two distinct “flavours”. The old style featured a solid axle end which turned on brass bearing inserts inside an oil-filled journal box cast as part of the truck. This is what is known in the trade as a “plain” bearing – sometimes also referred to as “friction” bearings, although only after roller bearings became common. Modern railway axles use a self-contained, sealed package of roller bearings

Some lists of dates show the first usage of roller bearings on motor cars and some steam engines and freight cars in 1923 and first roller bearing on passenger equipment around 1926.

As far as I can tell from trolling through several lists of important dates, the first significant regulations about roller bearing journals came in the 1970s, with roller bearings required for all cars with 6 1/2″ by 11″ journals in 1972 and  roller bearings required for all cars with axle loading greater than 55,000 lbs in 1974. (Basically, larger 90-100+ ton capacity cars being built then.)

By 1991 all cars in hazardous materials service must be equipped with roller bearings and may not be equipped with plain bearings and in 1995 plain bearings were banned from interchange entirely.


The earliest freight car trucks were wood beam trucks with a heavy wood beam upper member and cast iron or steel journal boxes, spring hangers, bracing and other hardware. By 1870 “archbar” truck frames fashioned from heavy steel bar bolted together started replacing wood beam trucks as standard. Later trucks used various types of cast sideframes. Archbar trucks were banned from interchange service after July 1, 1940.

By 1958 all trucks applied to new cars were required to have AAR approved side frames with U-shaped castings and integral journal boxes. Cast truck side frames with T, I, or L shaped cross sections were prohibited under cars in interchange service.


The last few changes are harder to note quickly from a distance as they’re underneath the car, but can still be seen in a side view.

Ribbed-back cast iron wheels (left) vs steel wheels (right)

Modelers may have noted that there are generally two styles of wheels available with some model trucks available (either as replacement trucks or included in some full kits or RTR models). Some wheels have a fancy-looking ribbed back appearance, while others have a profiled but plain back face such as the truck at top right in the photo. (Of course, some model wheelsets also have a completely smooth undetailed [inaccurate] flat-backed design….)

The ribbed back wheels represent older cast iron (not steel) wheels. The ribs cast into the back surface of the wheel helped dissipate heat from friction. Steel wheels did not require or have these ribs.

In 1958 cast iron wheels were banned from interchange service, therefore ribbed wheels would be out of place on any model set in the 1960s or later.

This is also a good place however to mention different sizes of wheels. Generally speaking, most older freight cars had used 33″ diameter wheels. However cars of 100 tons capacity or above rode on larger 36″ diameter wheels. Many modern trilevel autorack cars ride on low profile 28″ wheels. If you’re replacing wheels on your model freight cars and aren’t quite sure whether you should be using 33″ or 36″ wheels, take a look at the CAPY or LD LMT data lines below the car number. If those numbers are around 200,000 (lbs) or above, use 36″ wheels. Around 150,000 (lbs) is a 70-ton car likely with 33″ wheels.

Brake Systems

KC brake piping diagram

The first Westinghouse air brakes were patented in 1869.

In the early part of the 20th century, the common air brake systems in use on freight equipment (known as K or KC brakes) were a simplified affair where the brake cylinder, air reservoir and control valve were all combined as one unit. The more modern air brake system design (known as AB brake systems) that most people will be more familiar with are quite visibly different, with separate components for the brake piston, control valve, and a large air reservoir with separate halves for service [regular] and emergency brake applications.

In 1933 AB brakes were required on all new cars and the older K/KC brake systems were outlawed from interchange service in 1953.

AB brake piping diagram

Dating via the Details: Freight Car Stencils and Labels

Ah. Historical accuracy. The interest of serious prototype modelers and bane of existence for period film makers. Modelers attempting to set their railroad in a particular time frame know that there are specific markers that can make or break the illusion that is being attempted. Things that can sometimes take a little (or a lot) of research to get right. Things like road markings and traffic signs (e.g. STOP signs were yellow prior to the mid 1950s), company logos in advertising signs and billboards, paint schemes and logos on railway equipment (such as CN’s iconic 1961 “wet noodle” logo or CP Rail’s 1968 “multimark” redesign), the particular equipment itself (like a particular boxcar design first introduced in 1979), and vehicles on the layout (“if it’s supposed to be 1969, who’s driving that ’74 Pontiac GTO parked at the station?”).

This Walthers-Proto model represents a CP newsprint service boxcar built in 1967, in its original paint. However the addition of several simple decals firmly move the date up to no earlier than 1978. (As-yet to be applied weathering will finish the presentation.)

This article will take a look at some of the specific freight car data and decals that when applied (or not) will firmly plant a car’s time period on one side or the other or the 1970s, and make a huge difference (along with an appropriate amount of weathering) in making the difference between for example a 1960-built boxcar in service in 1960, and a 1960-built boxcar in service in 1980.

(Note: decals for all of the details shown below can be found in sets from MicroScale, HighBall Graphics, or other.)

ACI Labels

KarTrak ACI barcode label used during the early 1970s.

ACI or Automatic Car Identification was, as the name implies, an experimental system in the 1960s to combine automatic identification of cars and their locations via coloured bar code labels that encoded the car’s reporting mark and number on each piece of rolling stock and trackside optical scanners that could read the labels to identify the cars as they passed. The data from the trackside readers would be fed into a computerized tracking system in order to improve the efficiency and accuracy of tracking the location and movements of railcars throughout the North American railway system.

Beginning in 1967, the US Federal Railway Administration mandated the use of ACI labels on all new freight equipment, with a target date of 1970 to apply the labels to all existing equipment. However in 1977 maintenance and reliability issues caused the system to be abandoned. Dirt, rust, fading, vandalism and damage to the labels all contributed to an up to 20% failure rate in reading the labels.

Therefore, after 1978 no new or repainted cars had ACI labels applied any more, and they could also be removed from existing cars, although many never were and while more and more rare now it is still occasionally possible to find an intact ACI label on cars with build dates from the mid 1970s that still bear their original factory paint.

Consolidated Stencils

Early style single-panel COTS used on new cars from 1972-74.

Sometimes also referred to as “COTS” (Clean, Oil, Test & Stencil) or, colloquially, “lube plates”, these distinctive white-bordered black boxes contained stencilled information recording the car’s build date and inspection and lubrication data for the axle bearings and air brake system. Prior to the 1970s, COT&S data was just stencilled on the brake system air reservoir and/or on a small patch near the truck bolster.

Beginning in 1972, the Association of American Railroads began a program of applying this data in the now familiar consolidated stencil block to new and rebuilt cars. The early version was a white-bordered black box containing the stencilled data (see above image).

In 1974, the Federal Railroad Administration began to mandate the application of these data blocks, and around the same time, the layout changed to a two panel design seen below. This was applied to new and existing cars throughout the rest of the 1970s.

Large two-panel COTS applied from 1974-1981. (More on that yellow dot on black square decal later…)

Alternate horizontal two-panel arrangement. Particularly common on flatcars for obvious reasons.

In the early 1980s, the consolidated stencil was modified and standardized to a smaller 3-panel arrangement (seen below) with two top panels for lube and test information, and a lower block that would indicate the cars built (and if applicable, re-built) date that would become the standard from 1982-2016. Around 1981 or 1982 a similar 4-panel block (with three upper panels and one lower strip) was briefly used, but due to its short longevity, was pretty rare.

Post 1982 3-panel COTS block applied to a CP Rail flatcar.

In 2016 the requirement for the consolidated stencil was dropped, and new or repainted cars no longer feature it. I’m still getting used to seeing freshly painted cars without that familiar black block – they feel almost naked somehow and that block was always a nice go-to for checking the car’s age if you could read the BLT date in the lower panel.

 U-1 Wheel Inspection Dots

Yellow circle/black square U-1 wheel inspection symbol, applied en-masse during 1978. This car also has a patch showing where an ACI label was removed for some extra historical flavour.

In the late 1970s the common cause of a series of derailments was traced back to a defective batch of 33″ diameter steel ‘U-1’ wheels from the Southern Wheel Company.

Accordingly, in March 1978 a massive inspection program involving all of the North American railways was implemented to find and remove from service all of the potentially affected wheels. All cars with 33″ wheels had to be inspected (cars with differing size wheels such as 100-ton cars with 36″ wheels were exempt), and if one of the U-1 wheelsets was found, the car was marked with a symbol consisting of a white circle superimposed upon a black dot indicating a wheelset that required replacing by December 31 of that year. Passing cars received a similar mark with a yellow circle in the black square. New cars built up to December 31, 1978 also received the yellow U-1 inspection.

Once the inspection program was completed, there was never a requirement to remove the inspection marks, and these can still be found today on cars with paint dates older than January 1, 1979.

Weight and Capacity Data

Weight data on a CP boxcar. “WW 1-76” at bottom right indicates the weight data was last refreshed in January 1976. This stencil is the most immediate and visible indicator of era on a freight car as it includes an actual hard date. The top CAPY line was also removed as redundant in the late 1980s.

Below the reporting marks and car number on any* freight car you will normally find a collection of cryptic looking numbers and letters. Those three lines of data provide important weight information about the car.

This weight data is read as follows:

“CAPY 157000” – (Capacity) the nominal design capacity of the car, rounded to the nearest 1000 pounds.

“LD LMT 157100” – (Load Limit) the actual maximum loading capacity of the car, rounded to the nearest 100 pounds. This number is calculated by subtracting the car’s light weight from the gross carrying capacity of the journal bearings.

“LT WT 62900” – (Light Weight) the empty weight of the car, rounded to the nearest 100 pounds.

Other nearby data includes:

“WW 1-76” – shop code (WW = CP’s Weston Shops (Winnipeg)) and date of the car’s last reweighing. This is also a key indicator of a car’s era. The initial weighing date for cars from the factory will be stencilled with “NEW” as the code.

“XM” – AAR mechanical designation. In this case, “XM” is the code indicating a standard boxcar. (See here for a detailed run-down of this classification system.)

But let’s take a moment to talk about that “CAPY” line for a minute. By the 1980s someone finally realized that it’s actually rather redundant with the load limit, and in 1985 the CAPY line was removed from the lettering requirements, and indeed made to be removed from the cars themselves. So over the next decade following 1985, this line would end up being painted over on many existing cars, and no longer applied on new or repainted equipment. So this is another visual marker that would firmly signal a layout’s time frame as 1985 or newer.

*Additional note on weight data – tank cars could be a little different however. As they were typically designed for a specific commodity, and owned/leased by the shippers rather than the railways, many tank cars only displayed *either* the CAPY or LD.LMT. stencils, even far before 1985…

Reflective Marks

A Canadian regulation in 1974 required reflective marks to be applied to all new freight cars. Marks are to be applied on both sides with one located outboard of each body bolster and remaining equally spaced along the car; cars up to 56 ft. long (over end sills) to receive four marks per car, cars over 56 ft. long, six per car. Marks are to be 4” diameter or square (applied as a diamond) 3M Scotchlite reflective sheeting. These marks were applied as well to older Canadian equipment that was shopped and repainted.

This requirement was Canada only, and not in the US. Looking at several photos of CPAA boxcars through the 1980s and 1990s it doesn’t seem to have been used even by CP and CN on their American service cars, or at least not consistently.

Reflective markings became widespread on both sides of the border in the mid 2000s with the introduction of requirements for yellow reflective stripes (a.k.a. “Conspicuity Markings”) in 2005. Each country had a distinct deadline for compliance: 2013 in Canada, 2015 in the US. A number of cars were proactively marked in 2004. By rule, the yellow reflective marks must be renewed every 10 years.

Orange Bands on Tank Cars

Procor LPG service tank car with 1980s-applied orange band marking identifying it as a pressurized gas tank car. (Photographed around 2013, it also sports the post-2005 yellow reflective stripes mentioned above.)

This was another Canadian-only requirement introduced late in 1979, which saw many tank cars in pressurized gas service have a 12″ wide orange stripe applied along the length of the car. I’ve posted in more detail on this in a previous post: Freight Car Friday #54.