Guidelines on the Use of Auxiliary Through Lanes at Signalized Intersections (2011) / Chapter Skim
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Pages 6-13
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From page 6... ...
The upstream ATL length should be sufficient to ensure the ATL is accessible throughout the cycle. Downstream ATL Length : T he downstream length of the ATL measured from the stop bar for the opposing direction and the beginning of taper.
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From page 7... ...
X T : The demand - to - capacity ratio for the through movement assuming the ATL is not in place . APPLICATION Similar to CTL s, ATLs are implemented to increase the stop - bar capacity on approaches at signalized intersections that represent a "choke point" along an arterial st reet.
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From page 8... ...
Page 9 Each of the configurations shown in Exhibit 2 - 1 consists of a right - hand lane addition upstream of the intersec tion and a right - hand merge downstream of the intersection. Results from a web survey conducted as part of this research effort found that 85 percent of ATL applications had both a right - hand lane addition upstream and right - hand merge downstream.
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From page 9... ...
The analysis of crash data certainly did not highlight any unusual safety concerns at the ATL sites investigated. GEOMETRIC AND TRAFFIC DESIGN Many fundamental geometric and traffic design principles of CTL s apply to ATLs: • The geometric design of th e ATL should meet driver s ' expectations ; • Signing and pavement markings should be applied to reinforce the messages conveyed by the geometric design of the ATL; • Adequate sight distance should be provided to adequately accommodate advance decision making and emergency stops; and • Driveways and other impedances should be located outside of the intersection influence area (which for ATLs includes the entire effective ATL length including upstream and downstream tapers)
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From page 10... ...
ATLs incr ease the total crossing distance for pedestrians, resulting in reduced pedestrian comfort and a lower level of service ( LOS ) for crossing pedestrians, per the Signalized Intersections LOS methodology for pedestrians included in the HCM 2010 ( 2 )
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From page 11... ...
Transit Bus stops could be located within an ATL on either the near side or the far side of the intersection , depending on transit agency policy, local land uses, and signal timing. Depending on the roadway classification and/or traffic volume, bus stops are sometimes also located within the near - side right - turn lane or in a bus pull out bay on the far side of the intersection.
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From page 12... ...
Other observa tions from the research indicate: • For relatively short cycle lengths, near - side bus stops had a limited impact on the intersection operations. • Far - side stops within the downstream ATL caused motorist upstream to reposition themselves.
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From page 13... ...
Aggressive drivers may choose to use the less - utilized ATL to by - pass vehicles in the CTL. Certain agencies, such as the Maryland State Highway Administration and Connecticut Department of Transportation ( 6 )
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