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Cartographic Display of Centerline Road Network

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#1
hasecbinusr

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I am in the process of teaching myself techniques and methods of network-based analysis and representation, and I've stumbled into a problem that I haven't been able to solve through googling and reading. 

 

Software Available:

- ArcGIS 10.4.1

- QGIS 2.14.1

- ArcGIS Pro 1.4.0

 

Data:

- Texas Department of Transportation's RHiNO dataset: http://www.txdot.gov...-inventory.html

 

Problem:

Because the data is a centerline road network, there are visual gaps in the data when displayed as-is. There are attributes in the associated table for road width, offset, number of lanes, etc. that would probably be useful in depicting the road network more accurately. For example, I want IH-10 to display as a split double line to represent both directions of travel with the appropriate offset based on the attributes in the table, similar to how Google Maps, Apple Maps, and OpenStreetMaps display their data.

 

Methods Attempted:

- Symbol Levels

- Cartographic Representation

 

First, is this possible? Second, what is it called? I would imagine that I'd be able to find information on it with the correct process name, but I haven't been able to find anything yet.



#2
Dennis McClendon

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Can you show us an example of the "visual gaps in the data when displayed as-is?"


Dennis McClendon, Chicago CartoGraphics
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#3
hasecbinusr

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This is the TxDOT_Roadway_Linework_Routed file.

Attached Thumbnails

  • RoadsComparison.png


#4
Dennis McClendon

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Well, this is a perfect example of why I often trace over and then throw away the linework from GIS.  But this linework actually looks pretty good, and I think you can get 96 percent of the way there automagically.

 

Presumably some attribute in the file allows you to determine the centerline of the main roadway, by number of lanes or route number.  Just make that line weight sufficient that the interchange ramps begin and end within it. For example, set ramps to 1 pt and freeway to 6 pt.  Clone the centerline and make that "median strip," 1 pt, same color as the ground.

 

There will inevitably be instances that don't work perfectly: left exits, Y interchanges where a freeway splits, when the carriageways are widely separated like on MoPac Blvd.  And for double-deckers like I-35 through central Austin, things get especially tricky. 

 

 

6ht1qxj.png


Dennis McClendon, Chicago CartoGraphics
chicagocarto.com

#5
David Medeiros

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Those don't look like gaps but high-occupancy overpasses that start and end mid lane in the highway. Have you checked the attributes for line type?


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#6
Hans van der Maarel

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I agree with Dennis, depending on the quality of your data you can get close to a perfect result but there will almost always be some manual editing necessary. Most GIS datasets are simply not designed for cartographic display or don't scale well.


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Red Geographics
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#7
hasecbinusr

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Dennis, these lines are the centerlines for the road network with centerlines for frontage roads. For example, US-75 is represented by three lines: right frontage, left frontage, and main lanes. In the attributes, there is roadbed width, road width, number of lanes, type of lanes (HOV, one-way, etc.), design of the roadway (divided/undivided), etc. 

 

David, that is indeed exactly what they are. I don't know a programmatic method to display lines based on attributes in the table. I was hoping someone here could recommend the right tool/method for this job.

 

Hans, is there a programmatic way to take a dataset like this and convert it into the kind of road network you see on Google/Apple/OpenStreet Maps?

 

Manually editing individual intersections is going to be a problem unless the cartographic representation can be stored. This road network updates annually and I need to be able to roll in the updates each year without re-drawing all of my roads.



#8
David Medeiros

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Cartographic representations in ArcGIS are a hassle unless you are planning to utilize this database as the master to a long line of map or atlas exports from it. If these are one-off maps, I wouldn't waste my time setting it up. (added: re reading your last post, maybe that's exactly what you need if this is to be updated annually).

 

Basic styling by attribute is a core part of both ArcMap and QGIS, you'll just need to investigate the tools in the symbology tabs for both. I'd start by looking for some good tutorials online. IMO, the map layout tools in QGIS are terrible, but it does much better graphic work in it's symbology especially with handling complex color overlays.  Arc by contrast has an easier to use layout tool, but limited advanced color and symbology functions.


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#9
Dennis McClendon

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You use the attributes in the database to assign different line weights and colors to different features.  I'd rely primarily on functional classification (FUN_SYS) and number of lanes (NUM_LANES).  So freeway-6 lanes might become 8 pt red topped by a 1 pt white.  Frontage-3 lanes would become 2 pt gray.  Ramp-1 or 2 lanes would become 1 pt red.  You see how that turns out, look at edge cases like Dallas Woodall Rogers or IH-45's interchange with IH-10 Houston, then adjust the line widths.

 

You'll never get an algorithmic approach to produce perfect linework, but you can get something good enough for many purposes without too much effort.  If you're working only with Texas, TXDOT's aversion to left exits will make things a bit easier, though you'll have to decide how to handle the double-deck sections of IH-35 Austin, IH635 Dallas, and IH-10 San Antonio.  I'd probably largely ignore them, same as lefthand express lanes.  Texas's two-way frontage roads with feeder ramps will need some examination as well.

 

A few minutes with this particular dataset looks like it's possible, but a bit tedious—and not beautiful.  I looked only at FUN_SYS and NUM_LANES, but to distinguish frontage roads from arterials, I'd probably also need to look at HSYS or ADMIN.

 

kuAq6NK.png


Dennis McClendon, Chicago CartoGraphics
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#10
Hans van der Maarel

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Hans, is there a programmatic way to take a dataset like this and convert it into the kind of road network you see on Google/Apple/OpenStreet Maps?

 

 

I've been thinking about various ways to enhance road networks using FME, but so far haven't come up with anything conclusive.

 

I have to say though that this particular set looks great for certain scale levels in that roads are displayed with a single centerline rather than one per travel direction (which is great for large scales but quickly becomes a hassle and is useless at smaller scales). For single-line roads I always employ the trick of displaying them with 2 lines: e.g. for highways a thick red line with a narrow white or yellow one on top. If necessary I even break them up into seperate layers and if things get really complex I even go as far as using seperate layers per 'level' of road, so that complex junctions are shown properly. It all depends on whether or not that information is there in the attributes.


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