CE 578 Highway Traffic Operations

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CE 578 Highway Traffic Operations

• Lecture 14 Modeling Climbing Lanes HCM 2000

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Objectives

1. Understand how to apply procedure for climbing
   lane (focus is on PTSF, but the procedure is the
   same for ATS)

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Directional Analysis for Specific Grade Section

• Choose section
• If single grade OK
• If combination grade
• Analyze traffic with peak traffic going up the
  upgrade
• Add climbing lane to each upgrade section
• Adjust PTSF and ATS of upgrade section for
  climbing lane effects

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Given Information for Climbing Lane
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Adjusting the Peak Direction Volume
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Adjusting the Peak Direction Volume (cont.)
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Calculating BPTSFd
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Calculating PTSFd
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Given Information for the Climbing Lane
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Adjusting for Climbing Lane Effects
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Adjusting for Climbing Lane Effects (cont.)
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Comparison of With and Without Scenarios

• PTSFd 70
• PTSFpl 33
• This is a very sizable reduction on the grade.
• Will the improvement be so pronounced when
  including adjacent highway sections?

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Including Adjacent Highway Sections?
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Including Adjacent Highway Sections? (cont.)

• ISSUE What is the best way to accommodate Lde
  on group of subsections.
• ISSUE Lde is the same for climbing lane and
  passing lanes
• What should we do?

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Including Adjacent Highway Sections? (cont.)

• AASHTO helps address this perspective issue and
  its associated conflicts through criteria 3
• Reductions in speed of 10 mph or more (focus is
  on the upgrade)
• Upgrade level of service of E or F (focus is on
  the upgrade)
• change of two or more levels of service from
  approach to specific grade. (focus is across
  adjacent sections)