The service flow rate is the maximum hourly rate at which persons or vehicles Service flow rate defined
reasonably can be expected to traverse a point or uniform segment of a lane or roadway
during a given period under prevailing roadway, traffic, and control conditions while
maintaining a designated level of service. The service flow rates generally are based on a
15-min period. Typically, the hourly service flow rate is defined as four times the peak
15-min volume.