Sub-problem 3a: Weaving Analysis

In this situation, we can test the sensitivity of the results to the estimate we make about the weaving movement volumes and show some common assumptions that are made in such situations using three scenarios.

In the first scenario, we assume that all the 23^rd street on-ramp traffic goes to I-787 north. This maximizes the weaving volumes. The weaving diagram for this scenario is shown in Exhibit 4-49.

For the second scenario, we’ll assume that the inbound flows go to the outbound legs proportional to the exiting volumes. Since the volumes at C and D are 3,992 and 1,013, respectively, 77% of the exiting traffic from both of the entering flows will go to C and 23% will go to D. This means the flow from A to C is 3,075 veh/hr (77% of 3,992) and the flow from A to D is 920 veh/hr (23% of 3,992). It also means the flow from B to C is 315 veh/hr and the flow from B to D is 95 veh/hr. The resulting weaving diagram is shown in Exhibit 4-50.

For the third scenario, we assume a larger percentage going to D from B, namely 40%. This reduces the amount of traffic from A going to D. Thus, the weaving traffic decreases and the non-weaving traffic increases. The weaving diagram for this scenario is shown in Exhibit 4-51.

Exhibit 4-52 presents the results for these three scenarios You can see that the density is greatest in Scenario 1, where the weaving volumes are the largest. The density is lower in Scenario 2, where only 77% of the vehicles getting on at B are assumed to go to C; and it’s the lowest in Scenario 3, where 40% of the flow from B goes to D. As the weaving volumes get smaller, the density should decrease.