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A radio-based, GPS emergency vehicle preemption system reduced the average response times by five to seven minutes on a busy corridor.

A successful deployment of a GPS-based preemption system in Savannah, Georgia

Date Posted

Traffic Signal Priority Control for emergency vehicle preemption

Summary Information

Along the busy corridor of DeRenne Avenue in Savannah, Georgia, emergency service vehicles frequently had to wait with other vehicles for traffic signals to change and lanes to clear. The corridor needed an emergency vehicle preemption system to enable faster response by emergency service vehicles, but the configuration of the corridor precluded the use of standard preemption systems such as acoustic or line-of-sight systems. After investigating different solutions, traffic engineers with the city recommended a radio-based GPS system. When emergency service vehicles turn on their emergency lights, a GPS is activated and synchronizes traffic and crosswalk signals in the forward path.

In 2007, the City of Savannah deployed a radio-based, GPS traffic signal preemption system for emergency vehicles along the heavily congested corridor on DeRenne Avenue, starting at Montgomery Street through Waters Avenue. The City installed the system at seven east-west signalized intersections, and equipped 41 ambulances from two private ambulance services with GPS radio units and sensors for triggering traffic signals to change. The sensors can trigger a signal change for intersections as much as a mile away.


Prior to deployment, emergency vehicles took up to seven minutes to drive through the DeRenne Avenue corridor. After deployment the ambulances could move through the corridor in just over a minute. Observing this benefit, other emergency services requested that their vehicles be equipped as well. Subsequently, the city expanded the deployment, and in 2010, installed the system at 73 additional intersections and equipped 147 police and fire emergency vehicles with the GPS radio units.
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