Sizing your network for major events

How do you size your system for the “big one”?
This is another case where precise analysis goes beyond the scope of this guide, but we can offer some helpful guidelines for major events. The guidelines are appropriate for planned events such as sports events and conventions or crime emergencies and natural disasters.

The simple rule of thumb is that, for major emergencies the capacity should be roughly three times of your normal weekly busy hour.

• Establish how much traffic is generated on your current system during the busiest hour of a typical week. For most Public Safety organizations it is Friday evening but your situation may be different.
• How can you find out? If your current system has some traffic logging features you can pull down traffic statistics from your system management terminal. Another good place to go is your logging recorder.
• If during your normal busy hour your users generate x amount of traffic on your radio system, aim for 3x capacity for major events.

This level of capacity cannot always be achieved because of lack of available frequencies or budgetary considerations. However, try to get to as close as possible to this guideline and focus your operating procedures on limiting radio traffic to essential subscribers during major events.

Why is the 3x rule just a rough guideline? A small rural department is extremely unlikely to need that much capacity regardless the circumstances – you simply may not have that many users and your emergencies may be limited in complexity, size and impact. At the other end of the spectrum, a major dense urban area in an earthquake zone, with a combination of large commercial centers, sports facilities and transportation hubs nearby may need more than the “3x busy hour” capacity.