Sub-problem 3d: Collector/Distributor Road

The difficulty with the weaving analysis is that there’s only one lane on the freeway, the C-D road. The weave is Type A: each of the weaving movements requires a lane change. All of the traffic coming from the I-787 SB loop ramp goes to Route 7 EB, and all the traffic going to the I-787 NB loop ramp comes from Route7 EB.

What do we do about the freeway that is only one lane wide? We will do a weaving analysis, assuming the C-D road is two lanes wide. We assumed the weaving section was 264 feet long with a free flow speed of 40 mph. The weave is Type A and the B-D volume is zero.

The results of this analysis are presented in Exhibit 4-61. The density is only 5.02 pc/mi/ln, the LOS is A, the operation is unconstrained, and the weaving and non-weaving speeds are about 33-35 mph. The number of lanes required (N_w = 1.18) is less than the number needed for unconstrained operation (1.4). Note the result of N_w = 1.18, which is not that much greater than 1.0. This shows that although we were assuming that the C-D road was two lanes wide, and the weaving section three lanes wide, only 1.18 lanes were required for the weaving movements to be unconstrained. The remaining 0.82 lanes were available for any non-weaving traffic using the C-D road as an alternative to the mainline lanes for Route 7 EB.