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create point shapefile of street intersections from polyline - ArcEditor

MichaelCatsos

I'm trying to create a point shapefile of street intersections in downtown Phoenix, somehow deriving the points from a lone street centerline layer. I have tried extracting polyline nodes to points, but nodes do not exist at all of the necessary intersections. Intersect-related solutions don't seem to be any help since I am only working with one layer.

I'm not experienced enough to understand most scripting. Is there any procedure to split polyline features into segments between each intersection? After that I could extract the nodes, then turn them into points.

Another option I have explored is creating a small buffer around the polyline features. Theoretically, the points where the buffers around each segment overlap represent the intersections. This method is more inclusive, including all the potential intersections, but I can not figure out how to "overlay" the buffer with itself. Is there some way to use overlay to extract the small polygons where the individual buffered segments overlap, even though they are all in the same layer?

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JasonMurray

Hi There,

Within the ArcToolBox, Selected Analysis Tools - Overlay - Intersect. Fill out the details in the pop up window and change the output feature type to Point and it will create a point feature from all the places where the two road types intersect. That is the method I use anyway.

LukeAllen1

Thanks Mike, I'll play around and see if I can come up with something

The reason I'm doing this is because I work for a water company in Florida, so its to compliment a pdf mapbook I'm making in case we have no internet during a hurricane (I don't just randomly look up 7 year old posts I promise )

MikeHargreaves

Luke, don't remember, though someone did put some array stuff up there. If you wanted to do manually, create enough fields for each street, and maybe a working field or two. Use Field Calculator with vb as parser and use InStr() to find location of 1st & and put that value into an integer working field (len). Then use that location to get 1st street using Left(AllStreetsField,len-1) and put remainder into another working field using mid(AllStreetsField,len+1,x) where x=field length - len + 1. then do again against remainder.

LukeAllen1

Mike cudos for the response time thought

Dont worry I figured it out - I guess I didnt edit my post in time, I did ask a question further down, if you can remember that far - dont worry if you cant though

Thanks again

LukeAllen1

Mike, could you share the python code for splitting the streets out separately rather than all be concatenated with the & symbol? - my python skills are still in the 'early' stage

MikeHargreaves

Luke, I'm supposed to remember something from 7 years ago!? I have a hard time remembering what I did last week...! In looking at what I wrote above, I believe I'm referring to the new field created on step 6...

LukeAllen1

Thank you mike, this was super helpful - you are my hero!

SubodhDhakal

I really like how all have come up with ideas, why cant ESRI just make a tool to do that. I in my workplace use ET Geowizard tool-->Export Nodes (Regular nodes which carrys UID from centreline) that does in one tool and does not have to worry about it. May be its esri's time to incorporate it in to their new version..

Subodh

DaleHoneycutt

I'm coming in late to this conversation -- there's a well-received blog all about this:

More adventures in overlay: creating a street intersection list | ArcGIS Blog

MikeHargreaves

Sure Lee,

It seemed like something many folks would need to do. And many others contributed.

Mike

LeeAllen

Thanks mhargreaves, your work here saved me hours of figuring this out!!

JoeDiStefano

so how exactly would I be able to build a point shapefile of all the intersections in an entire city without selecting the cul-d-sacs as points as well? Only using the Real Nodes that is no End Nodes.

Update: We're testing a post-process to our points, based on the Trim Lines command to get rid of dead-end lines, combined with a selection and erase on corresponding points. This seems to get rid of intersection points that lead only to dead-end streets; however, it does not work on cul-de-sacs that are actually described using a circular bulb at the end of the line. We're still working on a post-process to knock out the intersection corresponding to the street ending in that bulb...

cheers,
~Garlynn

RichardFairhurst

so how exactly would I be able to build a point shapefile of all the intersections in an entire city without selecting the cul-d-sacs as points as well? Only using the Real Nodes that is no End Nodes.

I use the Collect Events tool (all license levels) to collapse many overlapping points derived from the Featrue Vertices to Points tool with the Both Ends option (ArcInfo license required) into a single point with a Count value. The Collect Events tool does not preserve links to the original points, so I have to create a field in the origin and output to hold a text representation of the point XY values to join. I use State Plane points and find that 4 digit precision is more than sufficient, so my field is 28 characters long and encloses the X and Y coordinates in brackets. My formula for calculating the point value is done in Python and is:

Parser: Python

Pre-Logic Code:

def Output(FirstPoint):
  FPX = round(float(FirstPoint.split() [0]), 4)
  FPY = round(float(FirstPoint.split() [1]), 4)
  return "{%(FX)012.4f}{%(FY)012.4f}" % {'FX': FPX, 'FY': FPY}

Expression: Output(!SHAPE.FIRSTPOINT!)

By summariizing and pivoting (ArcInfor license required) the origin point street names and frequencies and then joining the summaries to the Collected Event points on the field I have calculated I can keep track of nodes that are made up of one point, multiple points but only one road, or multiple points and multiple roads (including how many points make up each road, so I know where T intersections occur and which road is the base of the T). My true intersection layer is an extraction of all of the points that came from multiple points and that have multiple road names (excluding points where only one of the two roads is a named road).

Everything in the Collect Events output with a Count of 1 is either a Cul-de-sac (which I divided into real constructed cul-de-sacs and legal paper road cul-de-sacs), a stub road that has no bulb and that concievably could be extended, or a topological error. I extract these sets of points out into their own layer and classify them accordingly. Joined with other jurisdictional maintenance information from my Centerlines this cul-de-sac layer allows me to automate the mapping of all cul-de-sac symbols that my jurisdiction maintains on our maintained road book maps directly from information entered on the Centerlines.

Topology and geoprocessing environmental settings helps avoid quantum shifting of the street lines, so I recommend using topology and geoprocessing enviromental settings for feature class extents and XY precision if you want to use stationary road end points that you can track and join by their XY positions.

JoeDiStefano

so how exactly would I be able to build a point shapefile of all the intersections in an entire city without selecting the cul-d-sacs as points as well? Only using the Real Nodes that is no End Nodes.

That's a great question. In theory, Network Analyst has the capability to give you the answer, but there are definitely not any tools built to just do that.

Mike from Sonoma County said that he did this through "cleanup"... Mike, did you mean manual cleanup, or did you develop an automated way to clean out cul-de-sacs and other dead-end streets, driveways, etc.?

Hmyounan

I just wanted to point out that you absolutely can run the intersection tool with only one input, select point as output type, and get the intersections.

That what i was looking for thanks

lesterking

so how exactly would I be able to build a point shapefile of all the intersections in an entire city without selecting the cul-d-sacs as points as well? Only using the Real Nodes that is no End Nodes.

EmanuelDjurasinovic

i have a other problem, i need to extract Adresspoits from Polyline, in the Table i have Leftfrom,Leftto,Rightfrom,Rightto...Adresspoints and i want to make points in radius of x meters, we have in one County 1,5 Mio. Adresspoints and i can not extract it...thanx for Help,best regards...Emil

DarrenWiens2

Yes, there will be problems. I think you can tackle this with:

for i in range(0,len(array))
    streetname = array

...it may be len(array)-1

MikeHargreaves

Thanks - that looks like just what I need. Will there be any problems when I try thirdstreetname = array[2] if there is not a third street?

LukasWrsch_0-1626170384184.png

DarrenWiens2

So, does anyone have a suggestion on how I can strip individual streets from a field containing something like MAIN ST & 1ST ST & B ST ?

In Python, you'd read the field values, using a SearchCursor, into a string variable. Then, use the Python .split method. For example:

array = yourstring.split("&")
firststreetname = array[0]
secondstreetname = array[1]
thirdstreetname = array[2]

MikeHargreaves

Thanks Jim,

As far as I can tell, road name changes and T-intersections all look fine. I debated whether to remove my freeways and such with overpasses from the original layer, but decided to leave them in, even if they are not really intersections, since folks still like to reference those locations. As far as I can tell, we don't have any intersections in the County with more than 4 streets. The last time I made intersections a couple of years ago, I did use some code that I found that used the buffer, but it was very slow, and I think my product this time was actually cleaner. Maybe it is not the same buffer - the one I used did not put all the street names into one field, but instead put them into separate fields, and then I had to run a model to compare each field to the others to make sure it was not a duplicate before adding it to the final intersection label field. After creating the new intersections this time, however, I found that someone was using those individual street name fields... So, does anyone have a suggestion on how I can strip individual streets from a field containing something like MAIN ST & 1ST ST & B ST ? I could load it onto the mainframe and use a programming language that I know, but I'm sure there should be a way to do it in Python - I just don't really know it at all. Seems like I should be able to search for the & and get its location, and then use that do a strip or something...

JimW1

Sorry for the delay. Your methodology is good.

From my experience look out for T-Intersections, places where road names change, highway interchanges, and crazy intersections (5+) as the spatial join and attribute carry can be weak.

I went through this about a month ago for a Canada-wide road network and broke down and used the topological buffer tool in VBA to get really clean intersection attributes.

MikeHargreaves

Okay, I've managed to get something, though it is not pretty. Here are my steps:
1) Create Version of centerline that only has named streets
2) Dissolve on full street name (e.g. MAIN ST - this will remove duplicates later)
3) Use Intersect on this layer with output type = point
4) Add XY coordinates to new point layer and create DissolveID field and set to X_Y as mentioned above
5) Dissolve on DissolveID field to end up with only one point per intersection
6) Add new field to your Dissolved Named Streets layer - make 150-200 characters to hold 4-5 street names, then use Field Calculator to fill it with street name and add an underscore "_" at the end (e.g. MAIN ST_)
7) Do a Spatial Join with your target being the intersection points, and the Join Features being the dissolved named streets layer. Right click on your new field in the Field Map of Join Features, and under Merge Rule choose Join. After running, your end result should look something like A ST_1ST ST_ All streets at the intersection will be included (I got up to 4), and only once each if you did the original dissolve.
😎 Use Field calculator to strip the last "_" and then replace the rest with " & " - set the Parser to Python, then use the following: !YourFieldName!.rstrip('_') and then !YourFieldName!.replace('_',' & ') Your final will look like A ST & 1ST ST

Now, all I have to do is create a model, so I'll remember how to do it the next time...!

MikeHargreaves

Okay, I'm confused. I did the Intersect on my centerline, setting the output to point. It created a multipoint feature, so I ran the multipoint to singlepoint. Then I added the DissolveID field, and did the dissolve, setting the street name first and last as the statistics fields. The problem I'm getting, is that at a T-junction, I have three points, with two having the same name, and sometimes the First and Last select those two and not the one with the different name. What happens when I have more than two streets coming together at an intersection?

JimW1

I ran the intersect tool from toolbox and it worked.....BUT there are now points for every line that meets up there....time to figure out how to unite all data into one point.

Make a dissolve field that is a concatenation of the LAT/LON or X/Y.
So for example:
DISSOLVEID = �??-75.123456_45.123456�?�
Each point at this location should have the same string. You can then dissolve by the DISSOLVEID string.
Otherwise there is always topological buffers in VBA/Python.

RickEhlin__Jr

Rick, the attributes of the road segments will be transferred to the point features appropriately. Try to run the Intersect tool and check the attribute table of the output point layer.

I ran the intersect tool from toolbox and it worked.....BUT there are now points for every line that meets up there....time to figure out how to unite all data into one point.

AlexeyTereshenkov

Rick, the attributes of the road segments will be transferred to the point features appropriately. Try to run the Intersect tool and check the attribute table of the output point layer.

RickEhlin__Jr

It looks like we've established how to get the point file (intersections) created, but that file has no usable data in it. How would you go about getting the street names that intersect into the intersection file? I can't find an automated solution to this...???

AlexeyTereshenkov

Thank you very much for pointing this out, I have totally missed this!

However, I believe that creating a geometric network in the case of having billions of links is still more efficient time-wise. After editing the underlying data, to get the new points of intersection is a matter of rebuilding network, but when running the Intersection tool one is supposed to run the whole streets layer as the input.

DarrenWiens2

I just wanted to point out that you absolutely can run the intersect tool with only one input, select point as output type, and get the intersections.

1.jpg

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Untitled.png

arcworkstation.bat.zip

RickEhlin__Jr

Is there someway to transfer the centerline names to a intersection_name field in the point file?

AlexeyTereshenkov

Hi Joshua,

Glad it worked out well for you. Geometric networks are indeed very good! But if you work with street data extensively, I encourage you to take a look at the Network Analyst geoprocessing tools - we have got quite a few new useful ones (ArcGIS 10). What's more, you can define your connectivity rules for your streets (end vertex or any vertex) and obtain system junctions that will get created upon the build of the network.

Consider using Topology toolbar as BRaffel mentioned as well! 🙂

JoshuaDamron

Alexey,
Thank you for your post!

Great idea, I just created a geometric network to place points at all of our street intersections. Quick and easy, had to do a little cleanup work as it placed points in all the cul-de-sac's as well. Now to complete my count on how many STOP signs we have...

I like it when I can place a thousand points in a few seconds 🙂

-Joshua

BRaffel

You could use the Planarize tool - this will break all of the lines where they intersect.

AlexeyTereshenkov

Hi,

Could creating a geometric network solve the problem? (ArcCatalog > Geodatabase > Feature dataset > Geometric network). Junctions will be created automatically at the intersections of the streets.

JohnSobetzer

I've used Hawth's Analysis Tools (free) to produce points at line intersections in the same layer, but I think it creates duplicates at each location which I removed by running a clean. That was many years ago. ETGeowizards has a Renode Wizard that from the help says it would analyze a line layer and it could create points representing the regular nodes where two lines intersect but it isn't one of the free tools.

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