This tutorial will show you how to use OpenStreetMap iD and Podaris' custom street network creator to model a new active travel link and analyse the resulting changes in accessibility to key destinations
The tutorial is presented in 7 short steps, in which you will be walked through how to make changes to a street network in OSM iD, apply these changes in Podaris, and analyse the impact these changes have on accessibility for local residents.
For this tutorial we will be focussing on a fictional case study in which Somerset Council are proposing a new public footpath and sequence of footbridges over the railway line and river Frome, to connect a new housing development to Frome rail stations. We will look at how to model these changes and analyse their accessibility impact for residents of the housing development.
Each of the steps below contain video-based instructions, and a summary of the key steps contained in the video listed below it.
Step 1 - Making changes in OSM iD
Summary of steps:
- Search for OpenStreetMap in your browser and open the OSM website
- Zoom in to Frome rail station
- Click the Edit button at the top of the screen
- Select Line - then click a point on the existing section of road near the station, move you mouse to extend the line across the rail line, and double click with your mouse to end the line
- Click on this line, and change the feature type to a footpath with bridge structure
- Repeat to create additional footpath lines and another footbridge, this time over the river Frome. Make sure you finish this sequence of new footpath lines by connecting it to Blackberry Road
Step 2 - Downloading the osmChange File
Summary of steps:
- Click the Save button in the top right of your screen
- At the bottom of the panel that opens, click the button that says "download osmChange file"
- Once downloaded, close the OSM iD page
If you have encountered any issues creating or downloading your osmChange file, you can download the version prepared on this tutorial here and continue with the tutorial.
Step 3 - Sourcing and downloading a PBF
Summary of steps:
- Search for "Geofabrik download server" in your browser and open the Geofabrik website
- Click through Europe -> United Kingdom -> England -> Somerset
- Click to download the somerset-latest.osm.pbf
If you have encountered any issues downloading your PBF, you can download the version used on this tutorial here and continue with the tutorial.
Step 4 - Creating a new street network; the do-something network
Summary of steps:
- In the Podaris homepage, go to the "more" dropdown and select Streets
If you can't see the Streets option in the dropdown menu, please get in touch with the team at support@podaris.com and a member of our team will enable this feature on your account - Click to add new streets, and set the privacy and location settings when prompted
- Open the Setup Streets tab and upload your change file and PBF so that:
- Network = Your PBF
- Change File = Your osmChange File
- Click Finish Setup
Step 5 - Creating a new street network; the do-nothing network
Summary of steps:
- In the Podaris homepage, go to the "more" dropdown and select Streets
- Click to add new streets, and set the privacy and location settings when prompted
- Open the Setup Streets tab and upload only your PBF so that:
- Network = Your PBF
- Change File = Left blank
- Click Finish Setup
Step 6 - Applying street networks to projects
Summary of steps:
- Create a new project in the normal way
- For your newly created project, go to the project settings
- At the bottom of the general settings tab, change the street network from default to your newly create do-something street network
- Save your changes
- Repeat steps 1-4 to create a new project with the do-nothing street network applied
Step 7 - Creating isochrones to calculate accessibility changes
Summary of steps:
- Working first in your do-something project, select the isochrone tool
- Click on the map at the location near Frome rail station where the road joins with your newly added footpath
- Update the isochrone settings to the following:
- Mode = Walk
- Road Network = Streets
- Step Type = Distance
- Step Size = 10mins
- Steps = 3
- Click Recalculate and Save
- Repeat steps 1-4 for your do-nothing project
To import Census data and add a query to your isochrone that will quantify this change in accessibility by number of residents:
- In the datasets section of the Layers panel, click the "Add from data library" button
- Select "Census Output Areas" and draw a large box around Frome that captures the entire area your isochrone spans
- Reopen your saved isochrone and move to the queries tab of the isochrone tool properties
- Add 2 queries, one for usual residents and another for households
- Click Recalculate and Save
- Repeat steps 1-5 for your do-nothing project
Now Try This...
Want to take your skills further?
Why not try comparing the isochrones for the Do Something and Do Nothing networks using the Difference analysis type in Podaris:Insight
This is a powerful tool that enables you to generate access time isochrones for two network scenarios, and then visually map the difference and quantify this change based on any queries you set.
Read more about the Difference analysis type here and try setting up the analysis yourself for this case study, or follow the steps below:
- Return to the Podaris homepage and click the "+ New" button to create a new project.
- Select Insight and select a Blank template, setting the Privacy to Private and the Location to Frome. Once created give your project a suitable name.
- Your Insight project is now set up ready for creating your first analysis! Click the "+ Create Analysis" button to get started.
- From the analysis type library select Difference analysis and click Create. This will generate a Difference analysis template ready for populating with your analysis settings.
- In the Settings page, fill out each section as follows:
- Basic information: Give your analysis a name and description that will be useful when you refer back to the project to understand what the analysis is showing
- Networks to compare: Set your "Do Nothing - Frome" project as the Baseline Network and your "Do Something - Frome" project as the Comparison Network
- Baseline Isochrone options: Set the Mode to Walk, since we are interested in how our new active travel link has impacted walking accessibility to the rail station (Note: You could also set this to cycling, and reduce the max. duration setting, in order to see the impact this new active travel link has on cycling accessibility).
Set the Type to To and the Destination to Manual; then click the pencil icon to open the map and mark a point on it by Frome rail station.
Set the Max. duration to 15mins. - Comparison Isochrone options: Set this setting to Yes - this means that the same isochrone options (15minute walking access to Frome rail station) will be used to generate the Comparison Network's isochrone as were set for the Base Network.
- Dataset queries: To set a dataset based Query, you will need to set your Frome census data up as a "Shared Asset" Dataset, rather than referencing it from your pre-set up projects. More information on this can be found here.
Once you have this Dataset created, search for and select it within the Datasets section of the Difference analysis template.
In the Queries section below, add a new query on "All usual residents"
- Your analysis settings are all complete - click Save and the Run Analysis!
When Podaris has finished running your analysis, the outputs will be displayed in the Results tab of that analysis run. These results are comprised of a visual map displaying the change in accessibility, alongside a table of results that show the change in accessibility for "all usual residents" based on the query you added in part 5(e) of the steps above:
