EMS response times

John Johnson


Since 2015, Milwaukee’s Emergency Medical Services have responded to nearly 450,000 calls for service–an average of 12 per hour. Over this period, they have maintained an average response time of just 5.9 minutes after the call was placed. In 90% of cases they have arrived in 8 minutes or fewer.1 EMS responders spend an average of 25 minutes at the scene of the call, which means that Milwaukee’s emergency responders spend about 43,370 hours attending to the emergency medical needs of the community each year.

Average travel times are similar across most of Milwaukee. In general, slower response times occur more commonly in hard-to-reach places (like Jones Island) and more far-flung, lower density areas, including the far north-western neighborhoods. The map below lets you toggle between average visit times and total visits across the entire city.

Summer is the busiest

There is some seasonal variation in the volume of EMS activity. July is the busiest month, averaging around 9,400 calls. February is the slowest, with fewer than 8,000.

Variations by day of the week are insignificant. The “quietest” day is only 5% slower than the busiest. Time of day matters more. EMS trips subside in the very early morning from about 3 a.m. to 6:30 a.m. They pick up throughout the morning commute and workday before slowing again in the late evening. A second burst of activity occurs shortly after midnight, no doubt due in large part to late night revelers.

This animation shows what one particularly busy day looked like for Milwaukee’s EMS services. 346 emergency visits occured on July 23, 2016. I was able to plot 295 of them. Red dots appear when the emergency responders arrived and remain for the duration of their visit.

Response times are still good on busy days

The correlation between response times and the volume of calls is slight. On average, EMS trips took just 30 seconds longer on days with 300 calls than days with 100. Somewhat to my surprise, there is no statistically significant correlation between response times and the number of EMS vehicles currently in in the field. This seems to suggest that the system has adequate capacity for current levels of use.

  1. I was only able to calculate travel times for 323,074 incidents.