Back Next

HCMAG Home
Overview
Introduction
Getting Started
Problem 1
Problem 2
Problem 3
Problem 4
Problem 5
Problem Index
Datasets
Search

Sub-problem 3a - Page 11 of 13

ID# C403A11

Sub-problem 3a: Weaving Analysis

Traffic from the on-ramp interferes with the traffic trying to get from I-787 to the off-ramp, which slows the flow rates on I-787 down substantially. The weaving speeds become low and the operation of the weaving section becomes sluggish.

We can now return to the peak hour factor assumption and see how it affects the LOS prediction. We will also consider the effects of the free flow speed assumption. We will use the PM peak hour for the tests, varying the peak hour factor from 0.8 to 1.0 and the free flow speed from 55 mph and 65 mph.

Exhibit 4-55. Density versus PHF for Two Speeds

 

The results of these analyses are presented in Exhibit 4-54. Although the level of service changes only in the last case, an examination of the densities and speeds shows that the peak hour factor and free flow speed assumptions are important. As the peak hour factor increases, the density of traffic in the weaving segment decreases and the speeds increase. As the free flow speed increases, the densities decrease and the speeds increase. These trends are illustrated in Exhibit 4-55.

Exhibit 4-54. Location E, PM Peak Hour PHF and Free Flow Speed Sensitivity Analysis
Weave PHF Sff
mph		 Ww Wnw Sw
mph		 Snw
 mph		 S
mph		 Density pcpmpl LOS Operation of Type
E 0.80 55 5.73 1.17 21.69 35.71 26.04 60.21 F Constrained
E 0.85 55 5.40 1.08 22.03 36.59 26.52 55.64 F Constrained
E 0.90 55 5.11 1.01 22.36 37.3 26.99 51.63 F Constrained
E 0.95 55 4.85 0.94 22.69 38.21 27.43 48.14 F Constrained
E 1.00 55 4.61 0.88 23.02 38.97 27.87 44.99 F Constrained
E 0.80 65 5.73 1.17 23.17 40.31 28.29 55.42 F Constrained
E 0.85 65 5.40 1.08 23.59 41.39 28.87 51.10 F Constrained
E 0.90 65 5.11 1.01 24.00 42.41 29.44 47.33 F Constrained
E 0.95 65 4.85 0.94 24.40 43.37 29.98 44.05 F Constrained
E 1.00 65 4.61 0.88 24.80 44.29 30.51 41.10 E Constrained

[ Back ] [ Continue ] with Sub-Problem 3a