Sub-problem 3c: The Southwestern Quadrant

In the first analysis, we’re going to set the length of the first lane to 790 feet and the length of the second to 4,000 feet. This produces an influence area density of 3.9 pcpmpl. The long second acceleration lane reduces the density significantly. Where the merge starts and the combined facility is four lanes wide, our basic freeway section analysis indicated the density should be 20.8pc/mi/ln, compared to 3.9 pc/mi/ln.

Although the density of 3.9 pc/mi/ln implies LOS A, the methodology predicts LOS F; because the combined volume from the ramps and the freeway (5,400 veh/hr) produce an influx into the influence area, which is more than the 4,600 veh/hr allowed. Therefore, the merge has a LOS F.

Our analysis also indicates that the merge does not meet the second condition—volume exiting the influence area. The analysis includes a comparison of this volume (5,400 veh/hr) to a capacity for a 2-lane freeway section with a free flow speed of 65 mph (4,700 veh/hr). That comparison produces a merge failure, but the results could be incorrect. The true results should include a comparison of volume exiting the influence area (5,400 veh/hr) to a capacity for a 3-lane freeway section (7,050 veh/hr). This comparison shows that the merge does meet this capacity restraint.