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# Path of Travel - Orthogonal path

## Path of Travel - Orthogonal path

I often get into debates over the code intention of paths of travel, and it seems the most common opinion is to avoid "As the crow flies" diagonals. Unfortunately, we'd be stuck relying on the old railing-as-path method in this case. It would be extremely useful to be able to toggle ortho vs shortest distance.

I also have heard of some scenarios that require a path a fixed distance from a boundary wall (to feel your way through heavy smoke I suppose). This may be a third behavior worth considering.

I agree that this would be nice aesthetically, but I'm not sure how it would actually work. I've thought about it, because I've debated writing a Dynamo script to do just this, but the logic is unclear. There are so many different conditions that would have their own sets of logic. You'd have to develop not just the logic for each of those conditions, but the logic to determine which of those sets of logic to use in a given instance.

Again, I'd love to see this, but I'm not getting my hopes up. I think the best workflow for now and probably for a long while will be to use the path of travel tool as a reference, and then manually draw the actual lines that will show on life safety/evacuation plans.

Participant

Fair point. It is more than graphic though.. I'm concerned with the travel distance we use for calculations. I often find I can barely make a threshold for, say, one exit out of a room. But the orthogonal travel would have a longer travel distance, and would bump me into requiring two exits. I'm hopeful this can be done!

I'm not sure why you would think orthogonal lines would be better to calculate distances. People aren't limited to 90 degree turns.

Participant

I agree! But there is language in code that seems to discourage what they call "As the crow flies" paths. I think the logic is that while people are not limited to 90 degree turns, room layouts often do. I'm not a fan of this interpretation, but it's a very common interpretation that I've had to follow before, which is why I'd love to see Revit's Path of Travel accomodate.

You can currently add waypoints and manually adjust where the path takes you, but I agree, this would be great if it could be automatically done.

Collaborator

I agree, this would be great to be built in to the path of travel tool as an option.

In Ontario, Canada the code is also not very specific or defined for this so we tend to try and adjust our pathing location based on room use.

For example if we have a boardroom we wont have the line go 'as the crow flies' since there most likely is going to be a large table in the center of the room you need to go around.

It can also depend on what municipality and building department we are dealing with as some will interpret things differently than others.

Contributor

I mentioned this in the Revit Beta forums when this tool was being developed and I was ignored (I suspect because this tool was an acquisition that was bludgeoned into Revit without being a true integration).

For those debating the logic of "90 degrees" vs "as the crow flies" please consider that the logic comes from the movable- and changeable-without-a-permit nature of furniture vs doors and walls and stairs. With this required assumption, using what is better referred to as taxicab geometry represents a worst-case travel distance, hence why it is preferred or expected by building officials in operating under IBC.

The algorithm itself would certainly be more complicated than a glorified A* or whatever they're using now, but as a start could preferentially follow room geometry to corners opposite from doors, or midpoints if two doors, etc.

Alternatively, the Path of Travel tool would be more helpful if it could find the most remote points on a floor plan using taxicab geometry, and just provide a polyline tool that calculates total length and can be hidden via view template in every other view. I've made this most remote point tool before in Grasshopper, so I know it's possible and even trivial.

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