Industrial History: Railroad Scale Test Cars (2016)

They aren't. I've seen them in the middle.

They prefer to have them at the end because:

1. You don't want these cars to get banged around a lot and maybe have their weight change.

2. So you put them at the very end where they take the least wear and tear.

3. But they're not allowed to be the last car because they often don't have brakes.

So you put them as the second-to-last car.

This answer based on combining two of the captions from the page:

> Always the "Second to Last Car in the Train"

> Andrew B Baird: No brakes so it is not permissible to be the last car.

And

> The scale cars are now more robust? I notice that this car is not on the end of the train.

Speculation: the car weight would change as the brake shoes are worn down / eventually replaced. A minute difference but still a difference: https://www.wabteccorp.com/freight-car/braking-systems/brake...

Don't know about railroads, speculating here: Perhaps the brakes wear down over use, which would loose weight over time?

They must be rare, I’ve never seen them in North America.

In Europe they all used to be compared to the standard scale railcar which was kept in Paris. Recently standards have been updated to only rely on universal constants. So now European freight is measured in terms of the speed of light.

> Some yards have scales to weight freight cars to determine billing, acceptable axle loadings, etc. Periodically a test car will be put on the scale, and its reading better match the weight of the test car. Note that they are neurotic about handling these cars gently so nothing gets knocked off and changes the weight.

My guess is the scale cars never leave the rail yard.

But https://lionelllc.wordpress.com/2012/01/13/freight-car-frida... says they're owned by the railroad and sent around so perhaps there's a chance.

It sounds like they're most likely to appear on rails that carry bulk goods, and most railways now ship containers (which will be weighed otherwise, probably by the crane loading them).

The second picture on Wikipedia is of a British one [1].

And [2] have modern ones for hire, but there's no picture.

But [3] seem to use a crane and weights, rather than a truck.

("[Railroad] scale test car" is American, it should be something like "rail[way] weighbridge test truck" in British. I don't know this term in any other languages, so finding German and French ones is an exercise for someone else.)

[1] https://en.wikipedia.org/wiki/Scale_test_car

[2] https://www.brash-scales.com/weighbridge-test-unit-hire

[3] https://www.wyjs.org.uk/calibration/testing-of-weights-and-m...