The saturation flow rates of the feeding links are reduced due to spillback at the current
link. This is again illustrated in Figure 1 in which the westbound traffic between the two
intersections spills back to upstream link. Consequently, the southbound right-turning
traffic, northbound left-turning traffic and the westbound thru traffic of the upstream links
cannot enter the downstream link. In this case, the saturation flow of these turning flows
will be significantly reduced. Again, release 8 allows the user to specify saturation flow
rate reductions to the upstream links.