Total arrival time, defined as the duration from the moment a call is placed until the ambulance reaches the scene, is highly variable. This duration is affected by sequential steps, logistical hurdles, and environmental conditions. Understanding the components of this total time reveals why the process is more intricate than simply the ambulance’s driving speed.
The Phases of Emergency Response
The total time between a 911 call and an ambulance’s arrival is broken down into three distinct phases. The first is Call Processing Time, which begins when the emergency call is answered and continues until the dispatcher has gathered sufficient information and alerted the appropriate unit. Professional standards recommend this initial phase be completed within 64 to 90 seconds, 95% of the time, to prevent delays.
Once the unit is alerted, the next phase is Turnout Time, which is the time it takes for the crew to prepare and get the ambulance moving. For EMS calls, the NFPA recommends a turnout time of 60 seconds or less. This metric measures the efficiency of the crew and the station, ensuring they are ready to leave immediately upon receiving the dispatch notification.
The final and often most unpredictable phase is Travel Time, which is the time the ambulance spends driving from the station to the incident location. While Call Processing and Turnout times are internal measures of system efficiency, Travel Time is the component most affected by external factors like distance and traffic. The total elapsed time, from the initial dial to arrival on scene, is the sum of these three components.
Variables That Impact Travel Time
The actual Travel Time component is where the greatest variation in ambulance response occurs, largely due to geographic and logistical differences. In densely populated urban areas, ambulances are typically closer to a greater number of potential call locations, but they must contend with high traffic volume and congestion, especially during rush hours. Navigating crowded streets and multi-story buildings can add unexpected minutes to the final arrival time.
Conversely, rural and remote areas present a challenge of much greater distance between the ambulance station and the emergency location. Even with minimal traffic, the sheer distance and sometimes poor road conditions significantly extend the travel phase. Response times in rural areas can be considerably longer than those in urban settings, where ambulances can often reach a scene within 5 to 10 minutes.
Another significant variable is the Priority Level of the call, determined by the dispatcher during the initial Call Processing phase. Life-threatening emergencies, often categorized as “Code 1,” trigger an immediate “lights and siren” response. Less severe calls, such as non-life-threatening transfers or minor injuries, may receive a “Code 2” or “Code 3” response without emergency lights, resulting in a slower travel time. Weather conditions like heavy snow, fog, flooding, or road closures also act as external delays that slow down urgent travel times.
Establishing Response Time Benchmarks
Emergency medical services agencies use specific benchmarks, or goals, to measure their performance, which are not guarantees but targets for optimal service delivery. The most widely used standard for high-priority, life-threatening calls is the 90th percentile target. This means the agency aims to arrive at the scene within a certain time frame for 90% of those calls.
In many urban systems, this benchmark is set at eight minutes or less for the arrival of an Advanced Life Support (ALS) unit. This eight-minute standard has historical roots in research showing that survival rates for cardiac arrest decline significantly after that time without intervention. For rural areas, the benchmark is often less stringent due to the increased travel distance, sometimes extending the 90th percentile goal to 15 minutes or more.
These organizational goals typically measure only the Travel Time component or the combined Turnout and Travel Time. They do not always include the initial Call Processing Time, meaning the total time a caller experiences is often longer than the benchmark suggests. These standards are usually set by local or state regulatory bodies or industry consensus organizations.
Actions to Take While Waiting
While an ambulance is en route, the caller can take several practical steps to ensure the crew is able to locate the scene and begin treatment without delay. Making the location clearly visible is a simple but effective action, such as turning on exterior lights, a porch light, or a flashlight. If it is safe to do so, sending a person outside to flag down the ambulance can shave off valuable seconds that might otherwise be spent searching for the address.
Callers should remain on the line with the dispatcher, as they can provide immediate, life-saving instructions, such as guidance for performing Cardiopulmonary Resuscitation (CPR) or managing severe bleeding.
Preparatory Steps
- Quickly gather important information, including the patient’s current medications, known medical conditions, and any documented allergies.
- Secure pets or move any obstacles that could impede the crew’s access to the patient’s location.