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Length of deceleration lane

Alexandre Hering Coelho
Universidade Federal de Santa Catarina
Length of deceleration lane was posted on December 8th, 2017 at 12:15 PM EST
regarding Chapter 13: Freeway Merge and Diverge Segments

Hi! I have two consecutive off ramps in a freeway and I have to determine de length of deceleration lane for both. The situation is represented on the picture in this link: http://ahcoelho.net/downloads/question_ld_2_ramps.pdf. The length for the first ramp is 500 ft, ok. But for the second, 800 ft or 1300 ft? Thank you!

Scott Washburn
University of Florida
RE: Length of deceleration lane was posted on December 8th, 2017 at 12:47 PM EST

Alexandre: If this is an existing facility, I would use field observations as a guide. If the vehicles destined for the downstream off-ramp tend to move into the deceleration lane after they pass the upstream off-ramp, then use 800 ft. If this is the case, that would also simply the analysis somewhat, as using the full 1300 ft for the downstream off-ramp segment creates an overlap with the upstream off-ramp segment.

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