Help! Replacing Road Centerlines

[MichelleLewis]

Hi there,

I'm a relative newbie to GIS and I'm responsible for a statewide road network (yay for a team of one!). In order to begin to correct a ton of missing to/from address ranges, I'm believe I'm going to have to begin by removing the majority of one city's centerline data and replace it with better, more accurate data.

But since I've never done it and I don't know what I don't know, I'm not sure how to begin or what to watch for. So far, I'm analyzing the attribute tables between the 2 layers and I know how to identify which road segments I want to replace. But I would love some advice on how to go from here, what to watch out for, and how to ensure the ends of the replaced segments snap to the existing segments, so they become one cohesive set again.

I'm running ArcView 10 with Network Analyst (believe it or not), but I've been told I'll be getting upgraded to ArcInfo soon.

Thank you so much!

[JoeBorgione]

Let's see if I can shed some light by asking a few questions as well as a couple of suggestions....

Obviously, you should begin by filtering streets that are missing data:  No Street Name? No Address Ranges? Flag them some how; add an attribute called 'Suspect' or 'ByeBye' or 'Exclude' or something along those lines.  Type it short integer, and calc them to 0 (zero).  As you perform your filtering,  those that are Suspect, or should go ByeBye or should be Excluded should be calced to 1 (one). Ones and zero; pretty easy right?  That way you can symbolize them and see where the problems are.  You get more creative too; 1 = missing name, 2 = missing ranges, 3 = missing ranges right side, etc, etc.

Compare them spatially with what you want to replace them with: are you going to gain any additional useable data?  No sense replacing lousy data with the same, right?  Maybe you have data that has better attributes, but lousy geometry or the other way around.  You can use the Spatial Adjustment tool bar to transfer attribute values and/or geometry.

Seems like I've responded to your public safety forum posts; does you cad vender provide you any tools to check overlapping ranges, missing ranges, mixed parity, gaps,etc?  I know that Spillman and Versaterm both do; I use them both and they work really well.

Once you have your address attributes taken care of you can start looking at connectivity.  Build a network and start running some routes or service areas.  Your disconnects will show up in a hurry.  Be especially careful of freeway over and under passes; legacy coverage data will have your responders making 40 foot jumps to and from bridges!

Hope this helps...

[MichelleLewis]

That's great Joe!

Yes, I'm familiar with identifying and excluding "useless" data, I do that now with all our incoming original data. A cursory review of the new data I have shows it to be immensely more valuable - complete and accurate both spatially and aspatially - than what I currently have. So, from what I can see, I'll definitely be replacing the old with the new in probably a high percentage of instances.

I work with Spillman's CAD system, so I appreciate your suggestions on their tools. Admittedly I haven't worked much with the tools in Spillman - our contractor takes care of most of that. But we're trying to sever what is his duties from what are GIS (my) duties, as I learn more and am capable of taking them over. Eventually I will have all the GIS duties. So I'll work with him to see what tools I can use from their system. And I'm still crossing my fingers for an upgrade to ArcInfo.

Thanks especially for the info on building a network & connectivity. I know what you mean about over/under passes, they can certainly make the work interesting.

Thanks again - Michelle