Tutorials: Checking Drive Time Accuracy

It is highly recommended that users check Drive Time Network Trade Areas. The following Tutorial outlines how to identify the number of Census Areas included within Drive Time Trade Areas, as well as how to edit them.

Why do they need to be checked?

Explorer generates Drive Time Trade Areas for Network Locations's points (Coordinates) using a Network Analysis algorithm that travels along the road network, identifying all the Census Areas accessible within the defined time. This process takes into account speed limits, and assumes travel is conducted at 10:45am on a weekday with minimal congestion.

Due to the high level of accuracy, the time taken to travel from a Network Location's point  to a road is included, which can lead to smaller than expected Trade Areas when located in a shopping centre or pedestrian precinct.

If the coordinate is located inside a shopping centre, the Travel Time will include travelling from the store to the car park/entrance before connecting to a road. This means a Drive Time of 10 minutes may lead to only several Census Areas being included in the Trade Area. Whereas if the Coordinate had been located in the car park/near an entrance, the total area could be 50+ Census Areas.

Step 1: Prepare Definition File

Upload a Network Definition File with the desired Travel Time(s) and code in the PRIMARY, SECONDARY and TERTIARY columns. If using the geocoder for Network Location addresses it is also recommended that users validate the addresses.

Step 2: Check Areas

Once the Network has been generated, users can then export the Census Areas identified within the defined Drive Time for each Network Location, and summarise the file in Excel to identify those with an unusually small number.

1. Open the Network and download a Definition File from 'Export Options' menu.

2. Unzip the folder and open the .txt file in Excel, separating with the pipe delimiter '|'. This will create a table with a row for each Location and its corresponding Census Areas. (eg 100 rows for a Location with 100 Census Areas in its Drive Time).

3. Highlight the columns and Insert a Pivot Table.

4. Format the table to display the count of Location Names, to see the number of Census Areas assigned to each Network Location. As the downloaded file has a row for each Census Area in each Location, the number of Location Names signifies the number of Census Areas assigned to that site.

5. Check if there are any Locations that are disproportionately smaller than the rest of the Network. If so, users should adjust the site's coordinates in Explorer and regenerate the Drive Time areas.

Step 3: Edit Locations

Individually move the irregular Locations closer to a road and regenerate the Travel Times inside the system.

1. Within the 'Edit Network‘ menu select 'Add/Edit a Location’ from the Network Menu, then select a Location that was identified for fixing in the previous step

2. Under '1. Point Placement' select ‘Drop / Redrop Pin’ and click a spot on the Map is closer to a road. Tip: Switch to 'Satellite' view in the top left of the Map to find a car park/entrance.

3. Under '3. Trade Areas' select 'Travel Time' and enter the intended minutes travel, then 'Draw' to see preview the new Trade Areas. This may take a couple of pin shifts if there is a complicated road network.

4. Save Location and repeat for the rest of the Locations identified in the step above.

5. To view the generated Census Areas, return to Network view and click on the pin to view the Trade Area. Within 'Export Options' download the 'Locations List' to extract the updated coordinates.