Sub-problem 4a: Division of Alternate Route 7 for Analysis

Step 2. Results

Alternate Route 7 is a complex facility but if you follow the guidelines presented on the previous page, you should be able to identify the segments that make up the facility.

Let's start with the eastbound portion of the facility. We first look for factors that cause a change in either the demand or the capacity of the facility. The most common reason for a change in the demand is the presence of an on-ramp or off-ramp, where traffic either enters or leaves the facility. There are six ramps on eastbound Alternate Route 7. We should also note that between the I-87 and I-787 interchanges (specifically between the on-ramp from U.S. Route 9 and the off-ramp to I-787), there are two lane drops, each causing a reduction in the capacity of the facility. Thus, considering both the presence of ramps and the location of lane drops, there are nine sections along the eastbound portion of the facility.

Now let's consider the westbound portion of the facility. Again, there are six ramps, but since there are no lane drops or other factors that would cause a change in the capacity between the ramps, there are seven segments.

Remember that we also need to consider the three HCM analysis methods (basic freeway section, ramp influence, area, and weaving section) and determine how they apply. The eastbound portion of the facility includes a weaving section (remember our analysis in Problem 2 of this case study) and four ramp influences areas both in the merge area just downstream from the on-ramps and the diverge area just upstream from the on-ramps. The westbound portion includes six ramp influence areas, both merge and diverge areas. In total, there are eleven segments each for the eastbound and westbound portions of this facility.