Sub-problem 2c: What is the Level of Service at the Ramp Junction at the Northbound On-Ramp to I-87?

What input data is needed to conduct this analysis? To conduct an operational analysis of a merge area, we need to have the following input data:

What the primary measure of effectiveness for a merge point analysis? We are conducting an operational analysis, so we want to be able to forecast the level of service of the merge influence area. The HCM uses density as the primary measure of effectiveness from which to determine the level of service. Density is expressed in terms of vehicles per mile per lane.

What parameters are forecasted by the merge point analysis models in the HCM? To forecast the density of traffic in the merge influence area, the HCM uses several steps (and models). First, the flow rate in the merge influence area is computed. Recall that this is the flow rate in lanes 1 and 2 in the area just downstream of the merge. Next, the density in the merge area is computed and the level of service is determined. Finally, the speed is computed.

What are some of the limitations of the merge point analysis model that we must keep in mind when applying it to this sub-problem? One of the major limitations of the ramp junction procedure in the HCM is that it does not apply when demand exceeds capacity. If demand exceeds capacity, we need to consider another procedure, possibly microscopic simulation.