|
Sub-problem 3a - Page 12 of 13 |
ID# C403A12 |
Sub-problem 3a: Weaving Analysis
A peak hour factor of
1.0 and a free flow speed of 65 mph are required to get the weave to LOS E.
Also note that the highest density is 50% greater than the lowest. The
compound effect of changing these two parameters is substantial. Moreover,
the effect of the peak hour factor is more substantial than the speed.
Dropping the speed from 65 to 55, when the PHF is 1.0, raises the density
from 41.1 pcpmpl to 45. The change in speed is about 17%, while the change
in PHF is 20%; but the percentage changes in the density measure are far
greater.
Considering the poor
operation of this facility, it would be interesting to know if different
geometric conditions produced different results. We will consider the length
of the weave and the number of lanes in the weaving section.
The existing weave is
790 feet long. To explore the impact of changing that length, we will
perform additional analyses for lengths of 1,000 feet to 2,500 feet. We will
again use the HCM maximum of 2,500 feet for the length of a weaving segment.
The results of each of these analyses are shown in Exhibit 4-56. They show that a
minor increase in the weaving length (approximately 200 feet) will improve
the LOS from F to E. To reach LOS D, the weaving section would have to be
almost double its present length, or 1,500 feet.
|
Exhibit 4-56. Effects of Weave Length at Location E |
|
Weave Length |
Ww |
Wnw |
Sw
mph |
Snw
mph |
S
mph |
Density pcpmpl |
LOS |
Operation of Type |
|
790 |
4.61 |
0.88 |
23.02 |
38.97 |
27.87 |
44.99 |
F |
Constrained |
|
1,000 |
3.83 |
0.74 |
24.32 |
40.91 |
29.39 |
42.67 |
E |
Constrained |
|
1,500 |
2.77 |
0.54 |
26.94 |
44.15 |
32.30 |
38.82 |
E |
Constrained |
|
2,000 |
2.20 |
0.44 |
29.07 |
46.29 |
34.54 |
36.31 |
E |
Constrained |
|
2,500 |
1.84 |
0.37 |
30.85 |
47.83 |
36.34 |
34.51 |
D |
Constrained |
[
Back ] [ Continue ] with
Sub-Problem 3a
