Location of culvert with respect to RS

[teunotn]

If I specify a RS for a new culvert to what part of the culvert does the RS relate when I use metric (not numbered) RS?
E.G RS= 1000(m, ft) does this relate to the u/s end of the barrel or the centre or the d/s end or what?

[jarvus lunt]

RAS does not use the river stations (RS) for computing distances. The distance computations are based on the cross section lengths (overbank and channel).

For culverts, the key information is the length of the culvert. And on the Deck/Roadway editor, the "Distance" field in the upper left. This is the distance between the upstream cross section and the upstream face of the culvert.

[jfs175]

Jarvis is correct, any number numerically b/w the two bounding sections will work. Like he/she said, the key is the distance and length

Therefore, if your bounding sectios were RS 100 and RS 50, your culvert could be created as 50.01, 50.1, 99.1, 99.99, etc...

[teunotn]

Gentlemen, before your answer (thanks) I made my own "tip" (piece of useful info):

The exact location of a culvert is determined by its "bounding" Xs, i.e. the Xs immediately u/s and d/s plus the distance of the u/s edge to the u/s Xs and the length of the culvert. The RS of a culvert has not really a mathematical meaning, the only requirement is that its number lies between the RS of the u/s and d/s bounding Xs (see v.4.0 User's Manual p 6.32 bottom). These bounding Xs have to be at a minimal distance u/s and d/s of the culvert. As said before, the actual distances are given to the u/s Xs from the u/s edge of the culvert.

So if we use RS as chainages it is logical that the RS of a culvert is at its u/s edge. That is in fact what has been done in the twin pipe culvert, example 3. The situation is a bit complicated because the US are still using a mix of miles (=5280 ft)and feet. The lengths are measured in ft and the RS in miles. But if you convert everything to ft, or mi, or m you'll see that for the straight sections, the RS corresponds with the distance to the next d/s RS. Where there is a bend it may be that the RS corresponds with the distance of the main channel to the next d/s RS, I did not check.