Sub-problem 3b: Ramps

The HCM approximate capacities of ramp roadways come from Exhibit 25-3 in the HCM. The capacities are a function of the number of lanes on the ramp and the ramp free-flow speed.

The v/c ratios suggest that two of the ramps are close to capacity during a specific time of the day. The Route 7 EB/I-787 SB ramp is near capacity during the AM peak hour. Observations concur with methodology’s predictions. The characteristics of that ramp’s operation will be discussed in detail in sub-problem 3c.

The I-787 NB/Route 7 WB ramp is near capacity in the PM peak hour. We discovered two problems with this ramp. One relates to the weaving section, as we found in analyzing Location E in sub-problem 3a. The other relates to this new finding. In sub-problem 3a, we demonstrated that the I-787 NB flows created LOS F in the weaving section leading to this ramp. This ramp will be analyzed further in this sub-problem when we proceed with the merging analysis.