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Chapter 8: Left Turn Phasing—Permitted, Protected, or Both
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The purpose of this activity is to give you the chance to compare protected and permitted left turn phasing
treatments for your design problem and to select the most appropriate phasing treatment for the intersection.
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Select optimal left turn phasing treatment based on an analysis of performance data and observation
of simulation conditions
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VISSIM input file created in Activity #43
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Prepare a spreadsheet with required data, analysis, and conclusions as per Tasks 2 through 5:
Tab 1:
Title page with activity number and title, authors, and date completed
Tab 2:
Performance data comparing both left turn treatments
Tab 3:
Ring barrier diagram for your recommended phasing plan
How will you balance the relative advantages of permitted left turn phasing compared to protected left
turn phasing? Completing the following tasks will help you make this decision.
Make a copy of the folder that includes your VISSIM files fromActivity #43. Name this new folder “a50”.
Use this VISSIM file as the basis for your analysis and design of your left turn treatments.
Change the phasing plan to “permitted left turn” operation. See the VISSIM tutorial for help in making
these changes. Collect data for delay and queue length, as in previous design activities.
Observe the simulation for the two left turn options. Make notes on your observations on the operation and
performance of both simulations.
Compare the performance data and visual observation notes for both permitted and protected left turn
treatment. Based on this comparison, make a determination of your recommended left turn treatment op-
tion.
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Analysis and Design of Left Turn Treatment