Sounds like it was built to correct engineering tolerances, but the tolerances caused too much wear on the carriages. Somebody reported the wrong number somewhere, and that’s what caused this.

[–] BalpeenHammer 4 points 9 months ago (1 children)

Seems like a mistake they shouldn't be able to make.

[–] absGeekNZ 4 points 9 months ago

Agreed, it surprises me that this is able to happen.

I would assume that the bearers (sleepers) would be made in such a way as to locate the rails and keep the positioning at the optimum spacing.

[–] absGeekNZ 2 points 9 months ago (1 children)

Within tolerance is not, by definition, on target.

e.g. assume that the spec says 1200mm +- 4mm; running for 16km at 1196mm; this means that you are off target, whilst technically within spec it means that there is no margin on the negative side. Building at 1196mm effectively means your tolerance is -0+8mm which is very bad practice. A slightly thick rail takes you out of spec if measuring anywhere but the inside of the rail for placement.

[–] pennomi@lemmy.world 2 points 9 months ago (1 children)

That still means the spec is wrong, clearly.

[–] absGeekNZ 2 points 9 months ago (1 children)

That depends on what the spec says specifically.

I have worked with a lot of technical specs, some can be very specific about these kind of details.

When doing QC on a job, your goal is to hit target not just be within spec, questions should have been asked early as to why they were drifting off target, this is so you don't get to the edge of your allowable range.

[–] pennomi@lemmy.world 2 points 9 months ago

If the spec can be followed exactly and yield a bad result, the spec is fundamentally incorrect. (Even if that’s the usual way of doing things.)

[–] Vilian@lemmy.ca 2 points 9 months ago

how hard could be to fix that?