http://spc.kau.edu.sa/Files/320/Researches/52611_22917.pdf - Riyadh Saudi Arabia
Fire service goal is 7 to 10 minutes 90% of time (includes turnout time and travel time) - this translates to an average of 4.67 minutes (90% in 7 minutes) - or - an average of 6.68 minutes (90% in 10 minutes)
The existing 20 stations provide an average travel time of 10.6 minutes, average travel distance of 4.41 km, and a mximum travel time of 58 minutes.
Putting 20 stations in the most optimum locations would give an average travel time of 7.92 minutes, an average travel distance of 3.29 km, and a maximum response time of 27 minutes
27 stations would be needed to meet the "7 to 10 minutes 90% of the time" goal.