Monday, February 15, 2016

Dynamic Shortest Path in Ambulance Routing Based on GIS

When dealing with an emergency situation, quick EMS response is critical. Ambulance delay is positively correlated with increased ratios of serious to fatal injuries. If EMS vehicles could be routed more efficiently, response time could be minimized, allowing first responders to save more lives. In their article, Panahi and Delavar seek to develop a more effective routing software for emergency services – one that utilizes “dynamic routing” to find the true shortest path. 

GIS is already a useful part of the emergency response process, identifying the location of the caller, providing EMS vehicle locations to dispatchers, and determining routes for first responders. Current routing systems use a combination of street distances, speed limit, and historical traffic pattern information to plan the quickest route. Historical traffic patterns reflect the general levels of congestion along city streets at different times of the day. Although this expected congestion is an important component of travel time, it does not account for real-time shifts in traffic conditions – especially those caused by car accidents themselves. 

To improve upon this model, Panahi and Delavar advocate considering real-time traffic data when routing emergency vehicles. Their routing system creates an “initial shortest path” based on the starting location of responders, their destination, and historical traffic data. If real-time traffic data is available, the route is then modified in response to changing conditions. Throughout this process, routes can be visualized and displayed on road maps to both EMS drivers and management. 

Panahi and Delavar tested their model in a small area of Tehran, Iran, and found that their model reduced emergency response travel time by an average of 20%. The use of GIS-driven dynamic routing systems could mean more efficient – and therefore more effective – emergency services. 

Panahi, S., & Delavar, M. R. (2009). Dynamic Shortest Path in Ambulance Routing Based on GIS. International Journal of Geoinformatics5(1).

I have acted with honesty and integrity in producing this work and am unaware of anyone who has not. 
Simone Yoxall


  1. Another way this would be applied is road infrastructure. In places with high incidences of calls, emergency vehicle lanes could be considered for development.

  2. This sounds very useful! But any error - and google maps / apple maps / any electronic mapping system can be infamous for their errors - and lives are in danger. I think for a matter of life and death like an ambulance response, it's equally important to have knowledgeable driver who will catch and correct any mistakes the mapping algorithm might make.