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Sub-problem 3a: Weaving Analysis

The results for these three performance analyses (Datasets XX, XX & XX) are shown in Table 2a-2. Due to the relatively low volumes, the LOS did not change greatly as we adjusted the distribution of the flows. This is important information. It means you don’t have to be extraordinarily worried about being precise about determining what the distributions are. It also means the facility’s performance is not that sensitive to what the distributions are. So if the distributions change from day to day or for other reasons, you’re assessment of the facility’s performance is still valid.

Table 2a-2. Flow Distribution Analysis Results
Scenario Ww Wnw Sw mph Snw mph S mph Density pcpmpl LOS Operation of Type
1 0.7 0.42 47.35 53.79 51.53 24.21 C Unconstrained
2 0.65 0.34 48.35 55.94 53.58 23.29 C Unconstrained
3 0.61 0.3 49.1 57.46 55.13 22.62 C Unconstrained

You should also realize that as the overall volumes in the weaving segment increase, these changes in the flow distributions will become more significant. If we focus on the changes in the densities, we can see that as the total number of weaving movements decreases the density decreases. You should also notice the impact that the distributions have on the various speed measures. As the weaving movements decrease and the non-weaving movements increase, both the weaving and non-weaving speeds both increase. This is to be expected because as the weaving volumes are reduced there is a decrease in the conflicts that arise in the segment allowing the speeds to increase. Therefore, the overall speed in the weave should also be expected to increase and the density should decrease.

Weaving Segment E. The weaving segment at location E is also interesting. It is a 3-lane, Type A weave located on I-787 northbound between an on-ramp (from Rte. 7 eastbound) and an off-ramp (to Rte.7 westbound). It is a short weave (792 feet) with heavy PM peak hour volumes. The weaving movements are easy to determine: very few if any of the people coming from the on-ramp want to go to the off-ramp. So, all of the on-ramp traffic goes north on 787 and all of the off-ramp traffic comes from 787 north. The free flow speed of the freeway is 55 mph, while the speed of the on- and off-ramps is 25 mph. The analyses will be done with a peak hour factor of 1.0.

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