The saturation flow rate of the thru link is reduced due to blocking by spillover from the
adjacent right- or left-turn bay. This is illustrated in the TRAFVU (ITT Systems and
Sciences Corporation, Colorado Springs) display in Figure 1 in which the northbound leftturning
traffic (shown in the darker shade) spills over and blocks the thru traffic (shown in
the lighter shade). To explicitly consider this spillback effect, release 8 allows the user
specify a percentage of reduction to the saturation flow rate for the thru-lane group.
Release 7 assumes no saturation flow rate is reduced due to this spillback effect.