Monday, June 4, 2012

Travel time

The final element in this response time series is travel time.  Simply put, travel time begins when the wheels on an ambulance or fire apparatus start turning, and ends when they stop. Travel time is influenced by several different things: roadway capacity, traffic, weather, and navigation  accuracy--to name a few.  In the public safety business, travel time can generally be estimated by examining distance and the posted speed limit.

Experiments have shown that emergency responders are actually doing quite well if the travel time divided by distance averages the speed limit.  This is exactly how we conducted the analysis for Lincoln Fire & Rescue's fire station optimization plan.  Using GIS software, we just calculated the extent of the area that could be reached from each of Lincoln's 14 fire stations within four minutes if averaging the posted speed limit on the roadway network.  Fast driving does not help: smooth and safe wins the race, coupled with good navigation.  Remember when some Type A driver passed you, only to be stuck at the next light as you glided by in the adjacent lane?

Total response time, thus, is the sum of call processing time, turnout time, and travel time.  Of the three, travel time is the longest interval, and thus of particular interest when your goal is to maintain a reasonable response time to life-threatening emergencies.


Steve said...

Can you enlighten us on the ability of emergency vehicles to control traffic lights? Is that option available to both LFR and LPD? All vehicles, or just some? All traffic lights, or just some?

ARRRRG!!!! said...

My 'travel time' went down significantly when I went from this to one of these. Just think how fast I would get there if I had this.

Tom Casady said...


Fire apparatus are equipped with traffic signal preemption devices, and about 300 intersections in Lincoln can be controlled to provide a "green light corridor".

Anonymous said...


Anonymous said...

I have sat on this a few days but wanted to share an observation. Having a scanner and hearing the tones go out, I am aware of a significant amount of time an engine or medic is running but not moving, well after calling their status as enroute to a call.

Sometimes it is because they are waiting for a lone crew member to get in... maybe a trip to the can before rolling. I have no idea why this is the case in other instances.

Total time and call processing time are obviously easy to document. The travel and turnout times have to be skewed some by this.

Overall, it seems travel time is going to carry the most weight when making purchasing decisions for a new station.

When determining where a perspective new station would be placed, based on response times,the cumulative of turnout and travel (since call processing time should be pretty consistent) if turnout times are at acceptable levels and travel times are not, how can you make this determination unless the stats are based on true times when status changes?