Left-Turn Accommodations at Unsignalized Intersections (2013) / Chapter Skim
Currently Skimming:
Pages 12-22
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 12... ...
12 Introduction Once the decision has been made to provide a left-turn lane at a particular intersection, and the preliminary planning has been completed to determine the basic elements of the lane relative to the characteristics of the location (e.g., right-of-way, traffic volumes, etc.) , the dimensions and other physical characteristics of the lane must be specified based on geometric design principles.
|
From page 13... ...
13 representative of the vehicles likely to most commonly use the left-turn lane. When selecting a design vehicle, the designer must first consider the mix of vehicle types that use the adjacent roadway and then which of those vehicles are expected to use the left-turn lane.
|
From page 14... ...
14 same approach as the added turn lane was shifted to the right the full width of the turn lane. This condition is known as a full-shadowed left-turn lane.
|
From page 15... ...
15 For urbanized areas, short tapers appear to produce better visual "targets" for the approaching drivers and to give more positive identification to an added left-turn lane. Short tapers are preferred for deceleration lanes at urban intersections because of slow speeds during peak periods.
|
From page 16... ...
16 T-intersections, where there is no median in which to install a shadowed left-turn lane, and/or at locations where right-ofway is limited. At these locations, through traffic is directed to shift its path, while turning traffic can travel straight into the turning lane.
|
From page 17... ...
17 or high volumes. Therefore, the no-speed-reduction lengths given in Table 6 should be accepted as a desirable goal and should be provided where practical.
|
From page 18... ...
18 resulting capacity for the movement used in these procedures can have a significant effect on the calculated storage length recommendations as demonstrated by several researchers (11, 13, 14)
|
From page 19... ...
19 ing collector streets and most local streets, with a minimum length of 100 ft at local streets and minor driveways. The designer should also consider that if the appropriate design vehicle is a truck or other large vehicle instead of a passenger car, the minimum storage length must be extended accordingly.
|
From page 20... ...
20 provide space for signs, markers, and luminaire supports; and to protect pedestrians. To serve these purposes satisfactorily, a minimum narrowed median width of no less than 4 ft is recommended and one of 6 to 8 ft wide is preferred.
|
From page 21... ...
21 and continue through the intersection. It is commonly called a bypass lane.
|
From page 22... ...
22 It is often useful to provide additional guidance to through drivers that they need to change lanes at bypass lanes. This can be accomplished through dotted-line pavement markings that have a much shorter stroke length and shorter spacing than broken lane markings that permit passing.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.