Performing analysis in ArcGIS online

The story below will describe five different analysis tools available through ArcGIS online, including descriptions of the tool's function, the parameters used, an assessment of the tools function, how many credits it took, and a consideration of the resulting analysis. All data used is publically available via  MassGIS Data Layers.  The four original layers were  Bicycle Trails ,  Areas of Critical Environmental Concern polygons and boundaries , and  DCR Roads and Trails .

I first experimented with a couple of ways of combining relevant information from the areas of environmental concern boundaries and polygon into one layer. I did this by experimenting with both the "Summarize Data/Join Features" and "Manage Data/Overlay Layers" tool.

"Join Features" was run as follows:

This appears to have effectively joined the layers into a simple boundary layer, but with the data richness of the polygon layer, as seen below:

The fact that none of the boundary lines are visible in Figure 2, and that all polygons are completely encircled, suggests that the "Join Features" tool accurately captured all relevant information. According to the documentation, "Join Features" is supposed to "transfer attributes from one layer or table to another based on spatial and attribute relationships". For the process above, because there is no clear attribute relationship between the boundary and polygon information, I used a spatial relationship to append information from the polygon layer to the boundary layer. One shortcoming of that is that according to the  MassGov documentation for the data , the boundary layers were produced by snapping, and they are not necessarily relevant for legal purposes. However, for my use case that failed to matter. This process used 1 credit. The resulting analysis could be used to to complete the analysis I later completed using the polygon layer, although I chose not to in order to have a controlled set of source data for comparison purposes.

The fact that the original data for boundary lines was produced by snapping to political boundaries, rivers, etc. rather than dictated by the polygons was immediately obvious when I experimented with running the "Overlay Layers" tool to combine information from the polygon and boundary layers. This tool took 1 credit to run. The settings for this tool were as follows:

This intersection pulled data from the boundary layer which explicitly intersected with the polygon layer, and not all did. This can be seen when the outcome was mapped, as it is below with its table displayed:

While this wasn't a particularly useful outcome for my purposes of determining means of public access to areas of environmental concern, it could be very useful to determine discrepancies caused by the initial data creation process.

I then decided to investigate bike, trail, and road access inside the areas of special environmental concern. I did this using the "find existing locations" tool, and finding bike trails and DCR roads and trails that were completely within the areas of environmental concern polygons as indicated by the tool settings in Figure 5 below:

The DCR Roads and Trails output can be seen below (Figure 6), when run with the "Completely Within" expression. However, I decided that it would be more useful to my hypothetical explorer to know not just trail and bike access within areas of environmental concern, but bike and trail access TO areas of environmental concern as well. Therefore, I decided to find all trails and bike paths within OR within a mile of areas of environmental concern. This tool required 1 credit to run.

To find bike trails and foot trails within one mile of areas of environmental concern, I used the "Derive New Locations" tool with the settings outlined in Figure 7.

This tool worked extremely effectively to locate all bike paths either within or within one mile of the areas of environmental concern. It also required 1 credit to run. This was data that I saved to format for the final map.

After deriving new layers that were all bike paths within one mile of areas of environmental concern as well as all DCR roads and trails within one mile of areas of environmental concern, I decided to join these layers into a single layer that would describe pedestrian and bike access to areas of environmental concern. I did this with the Merge Layers tool, with the settings outlined in Figure 8. It took 1 credit to run.

Although the map in Figure 8 is zoomed in, I ran the tool over the full extent of Massachusetts. This would generate the final, combined layer that is visible in the production map below (Figure 9), which could be used by someone hoping to access or explore areas of special environmental concern either on foot or by bike. It could also be used by the DCR to limit access to the areas, should they be considered too sensitive for public visitation.

All data for the production above comes from freely available GIS data from the Massachusetts government. All data used is publically available via  MassGIS Data Layers.  The four original layers were  Bicycle Trails ,  Areas of Critical Environmental Concern polygons and boundaries , and  DCR Roads and Trails .