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Sub-problem 1a - Page 1 of 9

ID# C201A01

Sub-problem 1a: Maxwell Drive PM Peak Hour - Existing Conditions

The intersecting volumes by 15-minute intervals for the existing PM Peak are shown in Exhibit 2-7. You can also see that the peak hour is from 17:00-18:00. The total number of intersecting vehicles is 2,877 and the overall peak hour factor (PHF) is 0.94. The movement-specific peak hour factors range from 0.78 to 0.95, with those for the major movements being fairly high and consistent, while those for the the minor movements are lower and more variable. Moreover, the minor movements seem to offset each other in terms of contributing to the 15-minute volumes.

Exhibit 2-7. Maxwell Drive PM peak hour volumes - Existing Conditions
PM Peak Hour 2002 Eastbound Westbound Southbound

Intersection

Total
LT TH Total TH RT Total LT RT Total
16:00 43 232 275 231 37 268 64 38 102 645
16:15 32 207 239 236 54 290 68 32 100 629
16:30 46 231 277 239 54 293 71 52 123 693
16:45 43 228 271 231 42 273 65 38 103 647
17:00 57 230 287 244 70 314 90 50 140 741
17:15 49 230 279 281 45 326 108 55 163 768
17:30 52 219 271 255 54 309 75 34 109 689
17:45 36 189 225 276 50 326 79 49 128 679
Peak Hour Volume 194 868 1,062 1,056 219 1,275 352 188 540 2,877
Peak Hour Factor 0.85 0.94 0.93 0.94 0.78 0.98 0.81 0.85 0.83 0.94

For the purposes of this problem, we will apply the overall PHF of 0.94. It is, of course, also possible to apply each of the peak hour factors for the individual movements as discussed above, but doing so would presume that all of the individual movements peak during the same 15-minute time period of the hour. This does not happen very often, and so application of the overall PHF normally results in a more realistic assessment of intersection operations during the peak 15-minute period.

Analyses:

Base Case Analysis

Arrival Type Changes

Sensitivity to Data

Skipped Phases

Discussion:
 Why is it important to look at the variations in flows across the peak period? Is it reasonable to assume that the minor movements offset one another? Why or why not? 

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