Transit Time to Clinic

Categories Analytics, Healthcare, Transpotation

At the Children’s Hospital of Pittsburgh’s Primary Care Center in Oakland many patients rely on public transit for transportation to and from their doctor appointment. To support physician researcher Dr. Ana Malinow in investigating the extent to which long travel times negatively impact appointment keeping, I created an ArcMap accessibility utility to estimate the time in transit to reach the Oakland clinic from any location in Allegheny county.

Compared with using Google Maps or another travel planning service, the ArcMap accessibility utility 1) can estimate thousands of travel times imported from a spreadsheet and 2) may be used with patient’s Protected Health Information that could not otherwise be shared with a third-party.

To create the utility, I built a multimodal network dataset in ArcMap by combining the city street network with the Port Authority of Allegheny County public transit network. This enables either a Closest Facility analysis that calculates the walking plus transit travel time to the clinic from a list of locations (i.e. patient homes), or a Service Area analysis showing isochrones (graduated zones of travel time, e.g. the area in which it is possible to reach the clinic with 15 – 30 minutes of travel time).

The image above shows the paths travel times for a set of example addresses.
The image above shows the paths travel times for a set of example addresses.
The graduated shades above show zones of travel times to the clinic.
The graduated shades above show zones of travel times to the clinic.

To validate the travel time predictions created by the accessibility utility, I compared the utility’s predicted travel times to those provided by Google Maps and the Port Authority’s Trip Planner. I evaluated compared predicted times for ten points corresponding to the centroids of zip codes with significant patient populations.

Predicted Travel Time Comparison between the accessibility utility (ArcGIS), Google Maps, and the Port Authority's Trip Planner.
Predicted Travel Time Comparison between the accessibility utility (ArcGIS), Google Maps, and the Port Authority’s Trip Planner.

This validation shows that the accessibility utility produces travel time estimates substantially consistent with other travel time estimators.

To learn more about the project:
Check out aPowerPoint summary of the project.
Or download the full project report.

This utility has been used to support ongoing research in patient appointment keeping.

Mark is data science masters student and practitioner at Carnegie Mellon University with interests in transit, environmental policy and social justice.