An introduction to OS Open Rivers and OS Open Roads in ArcGIS

Ordnance Survey has recently released a new range of Open Data products - you can find more information on them here. This post will focus on the OS Open Rivers and OS Open Roads products, they are generalised products that provide detailed views of the watercourses and road network in Great Britain. Both are supplied for free as open data.

Both datasets work well to simply bring context to your map, for example you may want to show flooding hotspots or highlight a road incident. You can then share your maps to the public or to those who need it. In this post I will show you how you can use OS Open Rivers data for analysis by setting up a geometric network and performing tracing analysis. For OS Open Roads I walk-through setting up the network for creating simple drivetimes and routing. Both processes require you to have access to a Network Analysis license and ArcMap license at standard or higher.

You can download OS Open Rivers and OS Open Roads directly from Ordnance Survey’s website as shapefiles. For this post I have packaged the data up in a file geodatabase ready for you to use right here.

Using OS Open Rivers

Once you have downloaded and saved the file geodatabase, you can create a geometric network within it. To find out more about what a geometric network is, and what you can use it for, take a look at this article

First, create a feature dataset which contains the HydroNode and WatercourseLink feature classes. To do this:

    - Right click on the geodatabase then go New > Feature Dataset.

    - Import the features by right clicking on the feature dataset you just created,

      then go Import > Feature Class (multiple).

    - Select HydroNode and WatercourseLink features and click OK.

Now you’re ready to create a geometric network. You can do this by using the Create Geometric Network tool which can be found under Data Management Tools > Geometric Network. Import your Feature dataset:

create geo network.png

You can leave the rest of the settings as default then press ok to begin building your geometric network.

The OS Open Rivers is digitised in the direction of FLOW. Once you have created your network, you can use the ‘Set Flow Direction’ tool found under Data Management Tools > Geometric Network. Import your geometric network and run the tool with the flow option set to WITH_DIGITIZED_DIRECTION:

set flow.png

You’re now ready work with your geometric network using the Utility Network Analyst tool which can be enabled by clicking on Customize > Toolbars > Utility Network Analyst. You can place a flag on the network and query it to find answers like ‘Find Connected River’ or trace a river up or down stream. The example below shows the ‘Find Connected’ function.

Trace screenshot.png

Using OS Open Roads

In this section I will guide you through the steps to create a routable network using the OS Open Roads dataset. It should be noted that the OS Open Roads does not contain detailed turn restrictions, one way streets or other attribution that allows it to be used for ‘turn-by-turn’ routing or analysis. However, you can use OS Open Roads data to create a routable network and undertake analysis such as simple drive time or simple connectivity between locations on the road network. To create a routable network, first create a feature dataset which contains the ROADLINK and ROADNODE feature classes, to do this:

    - Right click on the geodatabase then go New > Feature Dataset.

    - To Import the features into the dataset, right click on the Feature Dataset

      you just created then go Import > Feature Class (multiple).

    - Select ROADLINK and ROADNODE features and click Ok.

Next, build your network by right-clicking on your Feature dataset and then select New > Network Dataset. To configure you network, follow these steps:

    - Give a Name for your Network , then click Next.

    - Select the ROADLINK and ROADNODE features to participate in the

      network dataset. Then click Next.

    - Select “No” to model turns in the Network.

    - Accept default connectivity settings, then click Next.

    - Select “none” to model elevation for network features

    - Accept default attributes for the Network Dataset.

Optionally you can configure driving direction for the Network dataset. Bear in mind that because turns are not configured, directions will not be accurate. To enable directions click “Directions”. Choose single field and the select “name1” for the description field.  In the General Tab  make ensure your you have configured your Street Name fields like so:

Network directions Properties.png

Click Apply and OK. You can optionally build a Service area Index, then click next. Building a Service Area index will allow you to optimise your network for speed. To learn more see the following help article.

Finish the wizard and when prompted build the network. You can learn more about how to configure a network dataset here.

You’re now ready to conduct some network analysis. To do this, use the Network Analysis Toolbar. To enable this click on Customize > Toolbars > Network Analysis. You will be able to query the network by placing a flag and then solving. You will be able to run routing analysis and create basic drive-time polygons using the create service area. The image below shows a combination of drive time analysis and route tracing.

route and drive time.png