Sub-problem 4b: Off-Peak Operational Analysis of Alternate Route 7

When we examine Exhibit 4-70, which deals with ramp operations, we can see one of the results of the d/c ratio near one for the weaving segment (segment 02). Both the demands on the on- and off-ramps are not completely served during this time period. Note for example that the demand for the on-ramp is 2,835 vehicles, while the actual ramp volume is 2,100 vehicles. But there are two points to make here that limit the applicability of these results. First, a limitation in the software used to implement the HCM did not allow entry of 2 lanes to the on-ramp. This produces an unreasonable result of ramp delay and queuing. Second, if this limitation were not present and the results were as shown in Exhibit 4-70, the unserved demand during this time period would be transferred to the next 15-minute time period. The same caveat must be applied to the off-ramp results. So, while we can learn an important point about oversaturated conditions (demand exceeds capacity), this example does have a limitation (due to current software characteristics) that we need to keep in mind.

These results apply to the off-peak period. In sub-problem 4c, we will consider the peak hour operation of the facility.