Trolley Tracks rule?

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05-02-2015 09:03 AM
MichaelGall
New Contributor

I’m working on some of the finishing touches for my model of the Germantown section of Philadelphia and it was brought up this week that I should look into trying to recreate the unique surface of Germantown Avenue, which includes a pair of trolley/streetcar lines running along the centerline with Belgian Block (ie. setts) lining the outer 1/3 of the roadway and generally accounting for the parallel parking lane:

https://www.google.com/maps/@40.035426,-75.174236,3a,75y,324.73h,71.95t/data=!3m4!1e1!3m2!1sMrK6vhAF...

I found a similar type of sketchup model using useful textures on 3DWarehouse, but the Belgian Block is in the middle of the tracks and the concrete is on the outside…just the opposite of the situation in Germantown:

https://3dwarehouse.sketchup.com/model.html?id=ub75d5171-aedc-4129-86b6-0a8cb14dd676

I’ve looked through the existing rail rules and can’t find something I could easily modify to serve this purpose, and my CGA skills aren’t strong enough for me to attempt writing a rule from scratch that could be applied to the street centerlines…or better yet, be a street texturing option within the Complete Streets rule.

Would any of you be able to help? (Our professor expressed hope that one of you may have a “drawer pull” rule written for just such a situation that I could use or modify)

Thanks so much in advance…I’m at a bit of a loss here.

-Michael Gall
Graduate Assistant
MS in GeoDesign ’15
Philadelphia University

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4 Replies
by Anonymous User
Not applicable

Hi Michael,

I'm curious about what a drawer pull rule is...

The Redlands Redevelopment example has a rail rule and a train model:

http://www.arcgis.com/home/item.html?id=9008aa9c322340edb2382f599cb3fb86

David Wasserman​ might advise on the complete streets rule.

Also, is Patrick Gahagan​ working with your class. He has CGA writing skills.

I'd think that in your class at least one person has attempted to write CGA rules. Are there any that have tried writing rules? This would make the whole class's abilities increase in the field of Geodesign.

Thanks!

Chris

MichaelGall
New Contributor

I think what he meant by "drawer pull" rule is that he hoped someone would have tackled this issue in the past and would have an applicable rule they could share, as if they just pulled an applicable solution out of a drawer.

And yes, we've covered some CGA via the tutorials and through working with Patrick, and most of us have written a few rules from scratch, but this is a bit more complex and we've only been working with CGA for the last few months, so it's all pretty new. 

The rail rules I've found so far create something more akin to a heavy rail line, not just tracks set into a roadway, and I was looking specifically for help in how one would go about incorporating them into a road rule.  Doing tutorials and watching someone else work on parameters in an existing rule set is a bit different from trying to conceptualize and execute this sort of rule from scratch.

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DavidWasserman
Regular Contributor

The problem with incorporating rail into a road rule is the start shape coordination issue. Different start shapes have very primitive information about each other and essentially exist in isolation. You cannot pass for example, a vertex or edge location from one start shape to another (at least to my knowledge-Chris Wilkins​ can correct me on that). So what happens with this problem is even if you create a rail allocation (which you can pretty easily actually by modifying the "Bus Only Lane" splits), you will have no way to coordinate how it should travel or align across an intersection procedurally. This is why the rail rule was made to apply to stand alone center line/street segments. Also, the hierarchical nature of CGA makes it hard (not impossible) to pass information from one shape to the next to begin with (requiring feedback oriented rules if you need to UP the shape hierarchy). It is not a perfect solution, but this is why rail is usually done as a stand alone rule separate from a road rule.

David

David Wasserman, AICP
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DavidWasserman
Regular Contributor

Hi Michael,

I have done just this before when using the Redland's Redevelopment rule and the Complete Streets rule. If you want a light rail line rule to match with the street rule I suggest making sure the rail line width is equal to an asphalt buffer that you create in the street. What takes the most time is making sure your rail line aligns with the asphalt buffer that you create, and also make sure that the curb radii is equal to that of the street ( so it aligns well on turns). When drawing your rail line, make sure you make the center line  vertices of the rail line match the break points of the street center line (this helped me a lot when I tried to align them together). Also when you use the created "Light Rail Car" from the rule, keep in mind that you can replace model, but also understand that it will only look ok on perfectly straight segments because of how the rule centers the rail car on the track.

David

David Wasserman, AICP