Sub-problem 3a: Shenendehowa Campus AM & PM peak - Existing Conditions

Let’s first look at the 15-minute intervals that makeup the AM peak. The volumes were shown in Exhibit 2-27. We have to create four datasets and get four separate results. Then we can compare those results with the original “peak hour” solutions we obtained, shown in Exhibit 2-30, to see where the differences are. We could also perform a pair of analyses in which the peak hour factors are different for every movement. That produces yet a third assessment of the intersection’s performance. Click here to see the input data for each of these analyses.

The delays and levels of service that we obtain for the AM peak are shown in Exhibit 2-31. The first line shows our original AM peak hour analysis. The next shows the results if we use movement-specific peak hour factors, and the last four lines show the results for each 15-minute interval during the PM peak. (Where a movement has zero flow, no LOS has been computed.)

Exhibit 2-31. Shenendehowa Campus AM peak hour delays by 15 minute interval

Dataset PHF Condition HV Correction Performance Measure EB WB NB SB OA

L T R Tot L T R Tot L T R Tot L T R Tot

22 Base Case Overall Yes delay 33.9 12.4 27.5 39.8 12.0 22.0 25.0 33.9 30.7 19.2 19.2 25.9

LOS C B C D B C C C C B B C

24 By Movement Yes delay 50.0 21.8 39.6 58.3 15.4 32.2 35.8 54.9 47.9 25.1 25.1 38.0

LOS D C D E B C D D D C C D

25 Internal 8:00-8:15 Yes delay 31.8 21.8 27.8 51.6 12.2 29.7 29.9 34.3 32.6 24.5 24.5 29.2

LOS C C C D B C C C C C C C

26 Internal 8:15-8:30 Yes delay 28.1 12.1 24.3 48.5 15.6 26.6 - 33.7 - 19.7 19.7 -

LOS C B C D B C - C - B B -

27 Internal 8:30-8:45 Yes delay 20.8 10.8 18.4 28.4 11.0 16.3 19.4 19.7 19.6 17.1 17.1 17.8

LOS C B B C B B B B B B B B

28 Internal 8:45-9:00 Yes delay 34.9 18.0 18.0 37.6 12.9 21.3 26.5 34.0 31.7 24.9 24.9 26.7

LOS C B B D B C C C C C C C

In the original analysis, the average delay per vehicle is 25.9 seconds. When we use movement-specific PHF values, the average delay is 38 seconds, or 47% higher. Is this realistic? We’ll see. The average delays on a 15-minute basis range from 17.8 to 29.2 seconds per vehicle. So the 38.0 seconds is clearly too high. The original analysis underestimates the delays during the peak 15 minutes where it is 13% higher.

Discussion:
Look at the datasets used for each of the 15-minute analyses. Check the values for the analysis parameters we set, such as the value for T, the duration of the analysis, and the peak hour factor. Think about whether you would have chosen the same or a different set of parameter values.

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