Design Guidance for Intersection Auxiliary Lanes (2014) / Chapter Skim
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Pages 101-111
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From page 101... ...
101 Conclusions, Recommendations, and Suggested Research Project Summary Researchers reviewed recent literature, state design manuals, and multiple editions of the AASHTO Green Book to determine the state of the practice and the basis for it. The research team also interviewed practitioners at state departments of transportation to gain additional insight into current design practices for deceleration lanes, multiple turn lanes, and channelizing island design.
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102 be taken to ensure that all participants are using the same definition. • Reasons for installing a deceleration lane and/or determining its length are typically based on various other geometric and traffic considerations, capacity, and speed being among the most common.
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103 Each of the identified sites was examined using aerial imagery to gain a better understanding of the key features of the design, as implemented. A single site considered representative of the design treatment was identified for each of the five design categories.
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104 left-turn lane saturation flow rate for these 10,023 data points was 1775 pcphgpl. At some DLTL intersections, drivers may choose one leftturn lane over another left-turn lane in anticipation of a turn at a downstream intersection or because of familiarity with a downstream friction point.
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105 expected, many sites with driveways/intersections as the friction point were associated with high numbers of lanes changes. The behaviors that reflected conflicts or potential conflicts were reviewed to identify if there were common elements.
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106 drivers or 10 ft/s2 for the most aggressive drivers) could be acceptable if site constraints or other factors dictate a shorter length.
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107 Section 9.6.2, Channelization (pages 9-93 to 9-94) • Recommended addition to the text on page 9-93 to promote the use of median storage for vehicles turning left from a minor road onto a divided highway.
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108 Section 9.8.3, Minimum Length of Median Opening (page 9-149) • Recommended revising text for clarity and to provide a reference to supporting research.
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109 factor is 1/1.05. Comparing the single-lane saturation flow rate (1900/1.05 = 1810 pcphgpl)
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110 This project studied operational characteristics and their relationship to design elements. A similar study on what design characteristics (e.g., lane width on approach, receiving lane/leg width, separation between opposing left-turn lanes, presence of pavement markings, location of downstream friction points)
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From page 111... ...
111 or unsignalized, presence of left-turn lane, presence of permissive-only or permitted/permissive phasing when signalized, posted speed limit, and others. • Entry angle for right-turn lane.
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