Overlapping Bus routs

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05-22-2013 11:07 PM
MohamedDarwish
New Contributor
I have three feature classes for the network:  
- Bus routes : having all bus routs split on each bus stop
- Bus stops : all bus stops location snapped to the ends of each bus route segment
- Walking routs : line connection between each two stations (face to face stations) to allow the passenger to cross the other side of street to change his direction using another bus.

the problem is the overlapped bus segments , Consider bus 66 and 19 are overlapping

[ATTACH=CONFIG]24608[/ATTACH]

like the attached image , if i'm solving the network to go from station 1 to station 3, if the solution started with bus number 66 it should continue with bus number 66 after station number 2 , but in some cases the route changes to another bus number however the same number 66 does exists in the second segment.

it should be bus number 66 and continue on 66 OR Bus 19 then continue bus 19 NOT bus 66 then bus 19
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22 Replies
MelindaMorang
Esri Regular Contributor
Hello everyone.  I just wanted to let you know about a new prototype tool from Esri's Network Analyst team which allows you to add GTFS public transit data directly to a network dataset.  You can use this network dataset with the Network Analyst tools to run time-aware analyses that incorporate the transit schedules.
You can download the toolset and instructions here:
http://www.arcgis.com/home/item.html?id=0fa52a75d9ba4abcad6b88bb6285fae1
Please do not hesitate to contact me at mmorang@esri.com with questions or comments about this toolset.
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JeremiahNieves
New Contributor III
#Jeremiah: I have seen your pdf. Why for bus and stop haven't use subtype in connectivity? so you have 1 feature class bus and 1 feature class stop.


Domenico,
    The PDF you reference is not my work. It is the work of a Master's candidate from the Netherlands named Reem Fawzy Mahrous. I agree that the connectivity policies in that PDF could have been simplified. At the time I began working on the research I had 1 year of GIS experience and my focus is actually public health and medical geography. Due to the time constraints of my senior thesis, I had to teach myself Network Analyst in the course of a month or two and was unaware of subtypes within connectivity policies. Thank you for bringing them to my attention; I'll be sure to read into it more and know they are a possible tool for the future.

On a separate note, I mentioned that I would work on a standalone tool that will allow my 3D network construction process to be repeated thus making hours of work  into minutes of work, depending on computing resources and input file sizes. I have attached the program and the readme file (please read that first). Make sure both files are in the same directory or the help button, within the GUI, will not work.  If anyone has any questions or feedback I would greatly appreciate it.
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ConorMoloney
New Contributor III
Jeremiah,

Do the routes have to be offset? And if so, how do you offset them?
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RamB
by
Occasional Contributor II
Happy to see my work being referenced here 🙂 . if you trace back the references you will find the first reference in a conceptual model from my 2008 work.


happy happy 🙂 🙂 , time for some beer.

regards,
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JeremiahNieves
New Contributor III

Jeremiah,

Do the routes have to be offset? And if so, how do you offset them?


Conor,

    Thanks for the excellent question as it is one that I find comes up often. Not offsetting is something I did not experiment with due to the time constraints of the original project I created the network for.  I'm not sure if 3D Analyst could support a purely vertical edge; perhaps Ms. Morang could shed some light on this? My main purpose for offsetting, other than the fact that I was following a large part of Mahrous (2012) procedure, was to ensure the connector line features would slope out from the street level stop to the serviced bus route(s). Additionally, were you to create a 3D network and not offset the routes, and there was a stop that serviced multiple routes, you would have a connectivity nightmare ensuring that the spatially coincident edges serving as connectors between street and route did not allow crossovers. This offset was the simplest solution and allows for simple connectivity between minimal numbers of features. This also makes the design very accessible for those with little network analysis or GIS experience.

     As for how I went about offsetting the routes, initially I used a small tool, see Copy Parallel below, but it resulted in little square "loops" on the corners of the new lines, both a lengthening and a distortion from the original line shape.
http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Copying_parallel_line_features/001t000...
However, when I made this program I found that iterating through each Point Object (vertex) in the Line Feature and editing the geometry directly by increasing the X coordinate by some uniform value was the most precise and expedient way of offsetting the routes. For example, If you had a vertex with an initial X attribute of 35000 ft from the projection origin and an initial Y attribute of 18500ft from the projection origin and put them through the offset portion of my script with an offset of 5 ft, the resultant X and Y attributes would be 35005ft and 18500 ft, respectively. ESRI's recent publication of Python Scripting for ArcGIS by Paul A. Zanderbergen (ISBN-13: 9781589482821) has an excellent chapter on modifying geometries through Python.

Let me know if that didn't address your question fully.

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ConorMoloney
New Contributor III
Thanks for the help so far. So I offset my routes by using Editing and then Move and it allowed me to move them a specified distance. Now I have built a network of just bus routes, but my stops and connectors don't seem to be working. What connectivity policy should I have? I used the one in the paper you referenced as a guide. I'll attach an image of my problem. Also you'll see in the Connectors image that the Real Stop are connected in a linear fashion as opposed to radial, is this correct? Also, when building the Network Dataset, do I build the Z Elevation?
[ATTACH=CONFIG]26456[/ATTACH]
[ATTACH=CONFIG]26457[/ATTACH]
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RamB
by
Occasional Contributor II
Conor,

1. make sure your routes are split at bus stops. use end-point connectivity
2. the solution is not difficult. I used a very simple logic: understand how network analyst works. Once you understand, just imagine raising each route to a unique height.
3. connect each stop to the route at its own height.
4. that is all about building the network.

Here I attach my very first model that I did for an Indian city in 2008. I did not even use python, it was a small excel macro. On Page 5-6 you will see the simple logical construction of the model.
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ConorMoloney
New Contributor III
Does it have to be end-point connectivity? My stops are not at end points only but are all along each route and are snapped to the edge. Should I have them snapped to the vertices for Any Vertex connectivity? Also, do the connectors need an elevation attribute, and if so should it be zero? When I compare my connectors to yours and jeremiahs, they are connected differently to the stops. With your connectors all pseudo stops are connected to one real stop, while mine that is not the case, with real stops only connected to one pseudo stop which in turn is connected to other pseudo stops. See in the image below. Does this make a difference? Sorry for all of the questions but I have been working on this for so long and it is still not changing at the stops for me

EDIT: I keep getting this warning "Warning: No route from location "Graphic Pick 1" to location "Graphic Pick 2". Error: No solution found." When I put the start point and end point on different routes

[ATTACH=CONFIG]26491[/ATTACH]
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RamB
by
Occasional Contributor II
I will give you answer, if you give me points... 😄

I think you are taking too much to digest. To understand the logic, do not do the whole city. Just do two routes, on a cross-road like network. Start with it.

If you really want to continue with your complete city network ( which I do not propose you to do at this moment), then please use 'planarize' tool to cut your roads and routes with false connectors, and then use end-point connectivity. However, I have to caution you, that using planarize on whole network with overirde any grade separations (flyovers, underpass, over pas, ramps) that do not need to connect will also get connected.  To avoid this behavior, you must unselect all your such grade separations before you hit 'planarize'.

again, start with a simple network and tackle the city later.

kind regards,
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ConorMoloney
New Contributor III
I will start smaller but I need to do the whole city for a project so hopefully I can build up to that. I don't think I have to worry about flyovers or underpasses just yet. Thank you for your help
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