Raised Intersections?

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06-09-2015 02:34 PM
MicahTaylor
Occasional Contributor III

I am working with Complete_Street Rule for a model I am building, and I was wondering how to create a ramp-like shape for a raised intersection.

(This street will intersect Pedestrian walkways with a raised brick intersection that cars can cross if need be.  When street meets intersection, there is a small concrete ramp that rises from street level to intersection level. I tried to use the "envelope" command in the rule file to raise the "Crosswalk" rule as the ramp, but that only works for one side of the intersection while the other three all taper the same way (not towards the intersection).  Any idea how to tell each crosswalk (all 4 incoming street segments) to taper towards the intersection? David Wasserman

5 Replies
MicahTaylor
Occasional Contributor III

Here is a snapshot of the intersection without the taper.GeoNetIntersectionSnap.JPG

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DavidWasserman
Regular Contributor

Hi Michah,

You would not believe how hard I tried to make it so the rule did this.... I have previous draft rules that I made in my spare time that experiment with this concept, but the problem is stability is hard to keep because alignment changes when you try to connect to multiple streets (the edge indexes changed for some reason between different segments starting and ending points...it was bizarre). So the behavior you are experiencing is the EXACT SAME I did. I was frustrated for weeks about this, and actually am glad to share that with someone else. When I first started on the path to try to do this, I did not know much CGA and deferred to an envelope function (made sense at the time and still might). Since that time, I have come up with ideas I have not tried yet. List below.

General Strategies:
I would suggest printing the edge indexes and seeing if there is any pattern with the various street parameters (connectionEnd vs. connectionStart).

See if alignScopetoGeometry can be used to anchor your orientation based on some discernible pattern.

1. Extrude up, comp sides and do a roof shed function on the side facing the street, but if it is not stable ALL SIDES (because if it goes into the intersection, you won't see it because the shape is above it,and on the sidewalk curbs, it should be under the sidewalk).

2. Extrude up, comp the top, comp the relevant edges (or again all edges if you have to), and insert a sloping object whose's height is equal to the sidewalk height.

3. Comp the top, try different alignScopestoGeometry, use the setback function on the appropriate edge, and make the border a sloped surface (angled split or roof shed), and then extrude the center to the appropriate height.

If you try this and any of them work let me know! I can't tell you how much I sympathize with this effort.

David

David Wasserman, AICP
DavidWasserman
Regular Contributor

Also, something that might help is trying to see if there is any pattern between the edge numbers and the ConnectionStart and ConnectionEnd Parameters. I have a sneaking suspicion that might be a way to align yourself, but again I have not checked...only gut feeling.
David

David Wasserman, AICP
MicahTaylor
Occasional Contributor III

Thanks! I will investigate more and keep you posted.  Your right, it is frustrating because its so close to working.  The roof shed idea might be the answer. I did not think about that.

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DavidWasserman
Regular Contributor

Hey Micah,

I will investigate some too. I should have taken a look at this a while ago. I think part of the problem is that the envelope function can do some weird things when it is not aligned properly. Crosswalks are not the ideal shapes to potentially be using them on.

Also if you want some guidance on design, I deferred to NACTO for mine. Their guidance on vertical control elements is pretty relevant. I deferred to speed tables for my raised intersection design.

Keep me posted,

David

David Wasserman, AICP