In queueing theory traffic tensity is a measure of how close a system is to capacity. Peoiple arrive to stand in a queue and and the same time people leave the queue to be served. The length of the queue fluctuates because people tend to join and leave the queue randomly but over a period of time these fluctuations tend to be smoothed out.
The ratio at of the rate at which people are joining the queue to the rate they are being serviced is called the traffic intensity.
If traffic intensity is greater than one the queue will tend to lengthen and more service points may need to be opened. If the traffic intensity is less than one there may be no queue at all at certain times.
Example: Customers arrive in a queue at the rate of three per minute and leave at the rate of one every 15 seconds on average.
The arrival rateand if customers leave the queue to be service on average every 15 seconds the service rate isper minute.