topic Re: Breaking sections by chainage values in Geoprocessing Questions

Breaking sections by chainage values

IoannisLampropoulos — Thu, 08 Oct 2015 15:39:39 GMT

Hi everyone,

quick question. I have a shapefile with the road network in terms of road sections. Each section is represented by a unique field in the table. I am processing some data from Excel that include each section multiple times. Now, two important fields in the Excel are start Chainage and End Chainage. I need to break down the above sections into these "new sections" with regard to the chainage lengths and create a new shapefile. Each of these lengths represents a different value that needs to be plotted accordingly.

Thanks in advance...

Re: Breaking sections by chainage values

WesMiller — Thu, 08 Oct 2015 17:43:48 GMT

Could you post an example of what you are trying to do? Sounds like you are selecting a street segment then getting the intersecting segments, but i'm not clear with your description.

Re: Breaking sections by chainage values

IoannisLampropoulos — Thu, 08 Oct 2015 20:23:20 GMT

Wes thanks for the quick reply.

So let me explain. I've got a map with the road network, where each section is represented by certain attributes (Section 1, Section 2, etc with additional info such as lengths, lanes, description etc). I am now processing some data in an Excel which contains the same sections as before. The point is that within these data, each section has more than one attribute values. E.g. In the shapefile Section 1 has a length of 2km. In the spreadsheet the same section has been divided into more than one "parts", according to the chainage (0-10m, 10-20m,.. 1990m-2km). Each "part" is associated with a different value, say for example from 0-10m there is a value of 1mm, from 10-20m a value of 2.5mm and so on. These values are the ones that I need to show in my map. However, I cannot find a way to give this spatial information to my table and create a shapefile. Of course, I can't join the tables since the relationship is 1:M and I'll lose the rest of each section's values.

Does this help?

Re: Breaking sections by chainage values

WesMiller — Thu, 08 Oct 2015 20:30:21 GMT

A picture may demonstrate a little better what you are trying to do. I think you are trying to do Linear referencing datasets in ArcGIS—Linear Referencing | ArcGIS for Desktop

Re: Breaking sections by chainage values

ChrisDonohue__GISP — Thu, 08 Oct 2015 21:14:41 GMT

One approach would be to split your line shapefile(s) up by specified distances and then join the table back to the appropriate segments (make a copy of the data and work on it).

Methods for splitting line features:

ArcGIS Desktop

Also, if you have the third-party Extension XToolsPro, they offer similar functions with a more automated means accomplishing them (Feature Conversions, Split Polyline).

Chris Donohue, GISP

Re: Breaking sections by chainage values

IoannisLampropoulos — Fri, 09 Oct 2015 07:24:34 GMT

Thanks for the reply. So, on the left I've got a shapefile with sections and their lengths. On the right side I've got an analysed table with the same sections, although they appear more than one times. So, for section 1000A/1 I need to attach the value of 17 only in the chainage between 138.029 and 148.04. In addition, for section 1000A/11 for example I need to include the values of 16.8, 17.3, 21.8, 4.4, 22.9 and 15.3 in different chainages. The same occurs to more than 100 sections, so a manual way is not an option.

Re: Breaking sections by chainage values

IoannisLampropoulos — Fri, 09 Oct 2015 07:25:49 GMT

Fair enough Chris and thanks for the reply. What if I've got different distances to specify for each segment?

Re: Breaking sections by chainage values

IoannisLampropoulos — Fri, 09 Oct 2015 10:38:24 GMT

Actually, I've managed to isolate the preferred chainage lengths by right-click in the table in the TOC and Display Route Events (linear referencing as you said). However, the selections are visible in the map but the attribute table is empty. I've tried to join the newly created table (the one with the route events) with my initial shapefile that contains the sections as whole lengths. The join works, meaning that I get a new table that has all the information that I need but after the join no lines are visible in the map. And still, since there is no spatial connection I'm left with a table or layer instead of a new shapefile.

Re: Breaking sections by chainage values

NeilAyres — Fri, 09 Oct 2015 11:39:51 GMT

When you did the Display Route Events dialog did you specify to create a LOC_ERROR field? This will help you find those records in your table which did not match via your FEATURE_LA / Section Label route id field.

And, if those are spaces in those field names, I would get rid of them. Spaces in field names can result in all sorts of strange things happening.

Re: Breaking sections by chainage values

IoannisLampropoulos — Fri, 09 Oct 2015 11:55:09 GMT

Thanks for the reply. It gives me a message saying: The table you specified does not have an Object-ID Field so you will be not able to select or edit the features in the resulting layer (apparently that's why my table is empty). However, I've got an OID Field set in my table. I am not sure how to proceed.

Re: Breaking sections by chainage values

WesMiller — Fri, 09 Oct 2015 12:05:51 GMT

Try using the Table To Table—Help | ArcGIS for Desktop tool

Re: Breaking sections by chainage values

NeilAyres — Fri, 09 Oct 2015 12:25:12 GMT

I don't think so. Done this many times.

Are you sure that your route identifier field on both sides actually match?

And I would still get rid of any spaces in the attribute names.

Re: Breaking sections by chainage values

IoannisLampropoulos — Fri, 09 Oct 2015 12:38:38 GMT

Thanks Neil, got rid of the spaces and the table is on. So the first part is achieved. Now, how am I going to relate this table with my initial shapefile? Remember that in my shapefile each section can be found once while in the table I created each section is found more than one times.

Re: Breaking sections by chainage values

NeilAyres — Fri, 09 Oct 2015 12:52:02 GMT

Sorry, not with you.

In the route events layer, everything in both the original polyline and the route identifier should be there.

If you now want to make this permanent, right click on the event layer and export into your db.

Re: Breaking sections by chainage values

IoannisLampropoulos — Fri, 09 Oct 2015 13:24:13 GMT

Yes Neil, you are right. Everything is in the table. I couldn't export it into a shapefile before and that's why I wanted to find a way to join my table with the existing shapefile. But yes, the table with the routes was exported just fine on its own.

Thank you very much Neil, Wes, and Chris.

Quick question since it crossed my mind. If I had a shapefile with say for example 1000 sections and needed to keep only 50 of them (just by knowing the names of the sections), what's the best way to do it?

Re: Breaking sections by chainage values

WesMiller — Fri, 09 Oct 2015 13:31:08 GMT

Select Layer By Attribute—Help | ArcGIS for Desktop "RoadNameField" in (Roads,Separated, by ,commas)

Re: Breaking sections by chainage values

NeilAyres — Fri, 09 Oct 2015 13:52:11 GMT

Or, in the mxd, copy the layer several times and use a definition query on each one.

Re: Breaking sections by chainage values

IoannisLampropoulos — Wed, 14 Oct 2015 09:32:11 GMT

Thanks everyone. Question answered.