dimension reference line in families

[HVAC-Novice]

I'm trying to measure pathlengths and created a family following these instructions. So far so good and it works measuring the lengths in 2D (horizontal). (hint: it recommends to make the family be "always vertical", but that prevents me from tracing the path in any direction).

It also recommends one could measure distance in 3 dimensions. this I want to use so I could have an egress path down the stairs and get the correct length. For that it recommends to "host the reporting parameter lengths on reference lines drawn between each adaptive point".

the problem is, for some reason I'm not able to dimension that way. No matter what I try, the dimensions don't really dimension the reference line length, but only the length on a plan (2D).

I think I'm missing some mundane technique in how to pick the ends of the actual reference line.

I attached the family so far.

[Alfredo_Medina]

Please attach the family. You said you did, but you forgot. I'll take a look.

[HVAC-Novice]

Sorry, must have forgottent o hit the attach button. Thanks for looking into this.

[Alfredo_Medina]

I made a test. First, I placed all the points at the same level. Then I went to an elevation, and lowered some of points, as if the path were following the slope of a stair. I measured the diagonal. The instance properties showed the correct length of the diagonal, not just the horizontal distance.

[HVAC-Novice]

thanks for checking. Did your measurements match exactly to the inch? I noticed they are a bit off and are more off when there is a large drop in elevation (like stairs).

I fixed an error (point 3 was labelled #7) and changed it to a generic family to work better as egress (attached). Anyway, this still seem inaccurate.

Before my original post i had that family on a site plan with 70' in between the points and lifting one point by 10', barely chaged the length by an inch. Only lifting it by 100', made a few feet difference, but less than one would have with some math.

I think the dimensions change because I made the family to not be "always vertical" as the original method recommended for 2D paths. When I see the dimension in the family editor, they stay in a plane. So the part where they somewhat change increase in size when raising or lowering, may be more a bug (family not set as "always vertical"and is not the actual dimension.

The inaccuracy seems to be most noticeable on steep changes. I dimensioned an 86' run (measured by dimensions) and Revit told me  it was 83.5' long. This isn't to bad considering the path went 2.5' up the stairs and 16' down the stairs. Since I pretended this was straight (on Y or X axis) to be able to measure in a section I have a >6' drop, but only 1'horizontal change section that has 2'in accuracy.

anyway, unless you need to measure an entire staircase over some stories and that is all of the egresspath, that probably is not a big deal. In my project the egresspaths aren't really impacted by a 2.5' error. Especially considering most designs probably don't have such detailed analysis of stairs. I could just use no shortcuts (i.e. route the egress path on the outside to have a longer run) to make up for it.

I still would like to know how to do it exactly, though.

This still beats my original egress path method of using a railing family (that I need to filter everywhere else) to run in the middle of the stairs.