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Sub-problem 2a - Page 1 of 2

ID# C202A01

Sub-problem 2a: Moe Road AM peak hour - Existing Conditions

Pedestrians, who must be taken into account during intersection analyses, have very different needs from those of the vehicles. Pedestrians have conflicts with the right-turning vehicles, they sometimes need an all-walk phase with no vehicular movements, and they need very different signal timings.

We will start our analysis with the signal timings. To cross the intersection, regardless of direction, the pedestrians always need two to three times as much time as the vehicles do. In fact, the pedestrian times tend to be distributed exactly opposite to the vehicle times. For the vehicles, the largest green time is usually needed for the main street and much less time is needed for the side street. Itís the other way around for pedestrians, where the street widths dictate the green times, not the pedestrian volumes. Most often, the street thatís widest to cross is the main street. And since the pedestrians cross the main street concurrent with the side street throughs-and-rights, the side street green time is boosted considerably. Similarly, the pedestrian times for the main street are much shorter than the vehicular times because the width of the side street is typically less.

In an intersection where vehicular greens are 30 seconds for the main street and 10 seconds for the side street, pedestrian timings need to be quite different. The pedestrian greens might be 20 seconds for the main street (7 seconds of walk plus 13 seconds of flashing donít walk, based on a 40-foot wide street) and 28 seconds for the side street (7 seconds of walk plus 21 seconds of flashing donít walk, based on a 70-foot wide street). In this situation, the usual solution is to boost the vehicular signal timings so that 1) the 24-second minimum for the side street is met, and 2) the 30:10 ratio for the vehicular times still pertains. Thus, the main street green would have to be 72 seconds to satisfy the 30:10 ratio, given the 24-second green on the side street. Assuming 4 seconds for the yellow and all red, the 48-second cycle without the pedestrians (30+4+10+4) becomes a 104-second cycle with pedestrians (72+4+24+4).

At Moe Road, pedestrians are important during the AM Peak hour. Students cross Route 146 going south on their way to school. Consequently, for an AM peak hour analysis, we have to take into account the pedestrians on the north-south phase.

This is the only time pedestrians are considered in the Clifton Park case study. Think about intersections in which you have had to take pedestrians into account. What did you learn? What were the constraints the pedestrians imposed? How often are they given appropriate treatment? At this intersection, or one with which you are familiar, what kinds of design features need to be incorporated to ensure the pedestrians are appropriately accommodated?

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