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Sub-problem 3b - Page 6 of 10

ID# C403B06

Sub-problem 3b: Ramps

Merging Analysis
In order to address the merge issues, we'll focus on two merge situations.

The analysis of a merging (or diverging) location involves several things:

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the concept of an influence area (i.e., where the merge occurs - the entering ramp and the two adjacent lanes on the freeway)

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the notion of an upstream ramp and a downstream ramp (either on- or off-ramp)

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the concept that there may be a test for facility failure (i.e., LOS F) that is different from having the LOS metric density in the influence area exceed a particular threshold

The HCM procedure focuses on an area about 1,500 feet long, including the acceleration or deceleration lanes, and one or two freeway lanes.

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