Site a new hospital
Open and save a map
First, you'll open an existing web map, save a copy, and explore the layers in the map.
- Open the Site a new hospital map in ArcGIS Online.
The map opens in Map Viewer.
- At the top of the page, click Sign In and sign in to your ArcGIS organizational account.
If you don't have an organizational account, see options for software access.
- In the Census Tracts pane, for Properties, click Close.
The Census Tracts pane closes, so more of the map is visible.
The map has four layers you’ll use for your analysis:
- Census Tracts
- Main Roads
- Loudoun County Boundary
Next, you’ll explore the data.
- In the Layers pane, point to the Loudoun County Boundary layer and click the Visibility button to turn it off and back on. Observe the changes on the map.
- Turn the three other layers off and on as well.
Next, you'll save a copy of this map in your ArcGIS Online account.
- On the Contents (dark) toolbar, click Save and open and click Save as.
- In the Save map window, for Title, type Site a new hospital followed by your initials.
- For the remaining fields, accept the provided values.
- Click Save.
A copy of the map is saved to your ArcGIS account.
Create a buffer around main roads
Next, you'll create the data to address the first requirement, which is to ensure the new hospital is located within 2 miles of a main road. You'll create a layer with a 2-mile buffer around the main roads. A buffer is an area around one or more map features, such as a point, line, or polygon, to a specified distance. The Create Buffers tool is one of the proximity tools that analyze map data based on how close or far away a second feature is. Proximity tools help you answer one of the most common questions posed in spatial analysis: What is near what?
- Confirm that all layers are visible, except Census Tracts.
- On the Settings (light) toolbar, click the Analysis button.
- In the Analysis pane, click Tools and expand Use proximity.
The proximity tools appear.
- Click Create Buffers.
The Create Buffers pane appears. In this pane, you can set the parameters for the tool. Required parameters are marked with a red dot.
- In the Create Buffers pane, for Input layer, click the Layer button and choose Main Roads.
- Under Buffer settings, for Distance values, type 2 and click Add. Confirm Units is set to Miles.
You'll indicate how you want overlapping buffers to be handled. You'll choose to merge any overlapping areas into one feature.
- For Overlap policy, click Overlap and choose Dissolve.
- Scroll down to the Result layer section. For Output name, type 2 Mile Road Buffer followed by your initials.
- Click Estimate credits.
Running an analysis tool consumes credits. Credits are the currency used across ArcGIS Online. They are consumed during specific transactions, such as performing analytics, storing features, and geocoding. Before running an analysis, it's a good idea to check how many credits will be consumed. When running analysis tools, the credit cost is typically calculated by multiplying the number of features by the credit cost of the tool. This analysis will consume 0.006 credits.
You can learn how many remaining credits are in your ArcGIS Online account if your organization administrator has enabled you to view that information. If it is enabled, at the top of the page, click your username and choose My settings. On the My settings page, click Credits to see how many remaining credits are in your account. If it is not enabled, contact your organizational account administrator.
- Click Run.
After a few moments, the new layer is added to the top of the Layers pane and drawn on the map. The blue areas show the 2-mile buffer around the roads.
You can see tools that have been run, their parameters, results, and any errors or warnings on the History tab at the top of the Analysis pane.
- On the Contents toolbar, click Save and open and click Save.
The current state of your map is saved.
Generate travel areas around the main hospital
To address the second requirement for the new hospital to be located more than a 20-minute drive from the existing main hospital, you'll create travel areas. A travel area is the area that can be reached within a specified time or distance along a street network based on travel mode. Travel mode refers to different ways of moving along a street, such as driving a car, riding a bike, taking a bus, or walking.
The Generate Travel Areas tool is a proximity tool. Like the Create Buffers tool, it analyzes map data based on how close or far away features are, but it does so along a street network.
- In the Create Buffers pane, click the Back button.
- Under Use proximity, click Generate Travel Areas.
The Generate Travel Areas pane appears.
If the Generate Travel Areas tool is not available, it's likely your account does not have the needed privileges to use it. Contact your ArcGIS Online administrator for assistance.
- In the Input layers section, click the Layer button and choose Hospital.
- Under Analysis settings, for Travel mode, confirm that Driving Time is selected.
You want to identify locations from which county residents can access the hospital within a 20-minute drive.
- For Cutoffs, type 20, and click Add.
- Confirm Cutoff units is set to Minutes.
- For Travel direction, choose Toward input locations.
The direction of travel matters because one-way streets and right turns may speed up arrival times in one direction, but not in the other.
You'll indicate how you want areas from different points to be handled. You'll choose to dissolve any overlapping areas into one feature.
- For Overlap policy, click Overlap and choose Dissolve.
- For Output name, type 20 Min Drive to Hospital followed by your initials and click Run.
ArcGIS Online uses a detailed up-to-date road network to perform the analysis. It does not use the Main Roads layer you see on the map. This analysis consumes 0.5 credits.
After a few moments, the new layer is added to the top of the Layers pane and drawn on the map. The purple polygon shows the area from which people can drive to the main hospital in 20 minutes or less.
- Save your map.
Combine buffers and travel areas
Next, you'll combine the layers you created to identify only those areas that meet the first two requirements. You'll use the data management overlay layer tools; these tools combine two layers to create a new layer.
Review your map and consider the areas that are within 2 miles of a main road and are more than a 20-minute drive from the hospital. You might describe the area as the result of subtracting the travel area from the buffered roads area. That's what the Erase tool does.
You'll use the Erase tool to create a layer that only contains the portions of the 2 Mile Road Buffer layer that are outside the 20 Min Drive to Hospital area.
- In the Generate Travel Areas pane, click the Back button.
- Expand Manage data and click Overlay Layers.
The Overlay Layers pane appears.
- For Input features, click Layer and choose 2 Mile Road Buffer.
- For Overlay features, click Layer and choose 20 Min Drive to Hospital.
- For Overlay type, click Intersect and choose Erase.
- For Output name, type Within 2 Miles Road and More than 20 Min from Hospital followed by your initials. Click Run.
This analysis consumes .002 credits. After a few moments, the new layer is added to the top of the Layers pane and added to the map.
- Turn off 20 Min Drive to Hospital and 2 Mile Road Buffer.
Point to the layer and click the Visibility button.
The Within 2 Miles Road and More than 20 Min from Hospital layer includes areas within 2 miles of roads and outside a 20-minute drive to the hospital.
- Save your map.
Create a layer that addresses all three requirements
Next, you'll combine the result of the last step, the Within 2 Miles Road and More than 20 Min from Hospital layer, with the Census Tracts layer to address the final requirement related to population growth. You’ll combine spatial and nonspatial requirements using a single analysis tool.
- In the Layers pane, turn on Census Tracts and turn off Within 2 Miles Road and More than 20 Min from Hospital.
- On the Contents toolbar, click the Legend button.
The legend for the map appears.
The final requirement states that the new hospital be in an area where the population is growing faster than 2 percent per year. The legend indicates those census tracts are the darkest purple areas on the map.
The good news is that with the work you’ve done so far, you can address all three requirements using a single analysis tool called Find by Attributes and Location. This tool allows you to find locations that meet requirements by writing a query built from one or more expressions.
Expressions are sentences that define how you want to narrow down which features in a map layer are of interest. Expressions that have no location component are called attribute expressions. Find the features in the Main Roads layer with the name equal to James Monroe is an example of an attribute expression. Expressions with a location component are called spatial expressions. Find the features in the Hospital layer that are inside the Loudoun County Boundary layer is an example of a spatial expression.
You’ll be building a query to find which features in the Census Tracts layer have population growth more than 2 percent (attribute query) and are inside the feature in the Within 2 Miles Road and More than 20 Min from Hospital layer (spatial query).
- In the Analysis pane, click the Back button. Expand Find locations and click Find by Attributes and Location.
The Find by Attributes and Location pane appears.
- Under Criteria, for Spatial and attribute queries, click Build new query.
The Query builder window appears. You'll indicate the query you’ll be building will be applied to the Census Tracts layer.
- For Find features from, expand the list and choose Census Tracts.
First, you’ll build an attribute expression.
- Confirm Census Tracts and Attribute expression are selected and click Next.
The Query builder window shows the start of the query, “Find features from Census Tracts Where All of the following are true.” That means you are looking for features in the Census Tracts layer that match all the expressions you’ll build.
The first expression you’ll build will find census tracts where the population growth rate is more than 2 percent.
- Expand FID and choose 2023-2028 Compound Annual Growth Rate (Esri).
The number in the 2023-2028 Compound Annual Growth Rate (Esri) field is a forecast of the growth rate for each census tract expected over the period from 2023-2028.
- Expand is and click is greater than.
An attribute query can include operators for numbers, such as “is less than,” or “is between” (two values) and operators for text, such as “contains” or “starts with.”
- Click Enter value and type 2.
Next, you'll add a spatial expression.
- Click Spatial expression.
- Ensure that the first menu is set to Intersects and the second is set to Within 2 Miles Road and More than 20 Min from Hospital.
Intersects, in this case, means “is inside of.” This expression will find any features in the Census Tracts layer that are inside of the feature in the Within 2 Miles Road and More than 20 Min from Hospital layer.
- Click Add.
The query, referred to as Features from: Census Tracts, appears in the Criteria section.
Next, you’ll indicate that you want your result to include only parts of the Census Tracts layer's features. That means the tool can break a census tract up if only one part of it, rather than all of it, meets the expressions in the query.
- Check the box next to Include only the parts of features that meet the criteria.
- Under Result layer, for Output name, type Final Result followed by your initials.
- Click Run.
This analysis will consume 0.076 credits. After a few moments, the layer is created and added to the top of the Layers pane.
The Final Result layer is hard to see, so you will make it more visible.
- On the Contents toolbar, click Layers and turn off the Census Tracts layer.
The final results of the analysis are clearly shown on the map.
- In the Find by Attributes and Location pane, click the Back button. In the Tools pane, click Close.
- Save your map.
You’ve found all the areas that meet the three requirements. Next, you’ll review your results.
Review your results
Once you complete an analysis, it’s a good idea to review the results and consider whether they are reasonable. This analysis is a first step in finding locations for a new hospital. Going forward, the county might need more data and analyses to address questions such as the following:
- Is there enough land for a hospital campus with many buildings or just a small single-building hospital?
- Is the local water, sewer, and energy infrastructure suitable for a hospital?
- Are there enough construction workers in the area to build the hospital?
- Are there medical staff who live in the area or who might move to the area to staff the hospital?
For now, you’ll review your results to see what conclusions you can draw about the identified areas.
- In the Layers pane, point to Final Result and click the Options button. Click Show table.
The table opens.
- Scroll the table all the way to the right so you can see the last field, Area in Square Miles.
Depending on your account settings, the area field name may be titled Area in Square Kilometers.
- Click the check box next to the first record to select it, and click Zoom to selection.
The map zooms to the selected feature.
This area has a strange shape. Can you explain why?
Turn the 2 Mile Road Buffer and 20 Min Drive to Hospital layers on and off to see how they impacted the results.
Do you think this area is big enough for a multibuilding campus?
Large medical centers and districts can cover 6,500 acres, or about 10 square miles.
- Uncheck the check box next to the first record and check the box next to the second record. Click Zoom to selection.
These two areas, which together cover more than 46 square miles, are a starting point for identifying a site for the new hospital. The governmental body might next look in these areas to identify properties available for sale, and whether the needed physical and human resources are available.
Next, you’ll close the table and return the map to its original extent.
- In the table, click Clear selection and click Close.
- On the map, click Default map view.
The map shows Loudoun County with your results.
- Save your map.
You’ll use this map as the basis of your report to the Loudoun County government.
In this tutorial, you created data layers using proximity and data management tools. You combined layers to identify areas within a 2-mile distance of roads, that are also outside of a 20-minute drive to the existing hospital. You then built a query using an attribute expression and a spatial expression to identify parts of census tracts with a population growth rate higher than 2 percent that fall within the required area. Finally, you reviewed the results of your analysis and considered what analyses might come next.
You can find more tutorials in the tutorial gallery.