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Pages 161-186

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From page 161...
... 8-1 8.1 Introduction The displaced left-turn (DLT) intersection, also called a continuous flow intersection (CFI)
From page 162...
... 8-2 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges 8.2.1 Motor Vehicles A DLT can have up to four crossovers at a four-leg intersection. However, most of the DLT intersections in the United States include crossovers on one or two approaches (Exhibit 8-2)
From page 163...
... Displaced Left-Turn (DLT) Intersections 8-3 approaches, use the displaced left-turns)
From page 164...
... 8-4 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges 8.2.2 Pedestrians Pedestrian crossings at DLT intersections differ from those at conventional intersections. The main reason for this difference is the position of left-turn lanes between opposing through lanes and right-turn lanes, which presents pedestrians with an unfamiliar crossing scenario (i.e., motor vehicle traffic approaching from a nonintuitive direction)
From page 165...
... Displaced Left-Turn (DLT) Intersections 8-5 Turns design flag in Section 4.4.10)
From page 166...
... 8-6 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges • The inside crossing achieves a shorter mainline crossing but requires more stages (compare c and d in Exhibit 8-5 to c in Exhibit 8-4)
From page 167...
... Displaced Left-Turn (DLT) Intersections 8-7 inside crossing design.
From page 168...
... 8-8 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges reduction in vehicle collisions and severity following the implementation of a DLT intersection (2) relative to comparable conventional intersections, while a 2018 study showed a total crash CMF of 0.88 (3)
From page 169...
... Displaced Left-Turn (DLT) Intersections 8-9 Exhibit 8-9.
From page 170...
... 8-10 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges For on-street bicyclists, a right-turn lane represents an uncontrolled conflict point. Depending on the distance from the intersection at which bicycle and motor vehicle paths cross, it may be a decelerating vehicle movement.
From page 171...
... Displaced Left-Turn (DLT) Intersections 8-11 8.3.2 Pedestrians–Key Safety Challenges An analysis of the design characteristics of the DLT intersection reveals several key safety challenges for pedestrians: • Providing a reasonable path and quality of service.
From page 172...
... 8-12 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges • Traveling along a turn lane and sharing the lane with turning vehicles (displaced left or channelized right-turn) can create difficulties.
From page 173...
... Displaced Left-Turn (DLT) Intersections 8-13 8.4 DLT Intersection-Level Concepts Three design concepts have been developed to present options for improving pedestrian and bicyclist safety and operational performance at DLT intersections.
From page 174...
... 8-14 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges or both; the concept also provides an example for carrying existing bike lanes through a DLT intersection. Consult Sections 3.1 and 3.3 to consider intended bicycle design users and guidance for matching a bicycle facility to speed and volume conditions.
From page 175...
... Displaced Left-Turn (DLT) Intersections 8-15 Flag Remaining Description Mode/Travel Path Motor Vehicle RightTurns (Section 4.4.1)
From page 176...
... 8-16 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges bike lane would be an appropriate design technique for locations with relatively high motor vehicle volumes, speeds, or both. The separated bike lane would provide a low-stress riding environment and encourage use by less confident bicyclists.
From page 177...
... Displaced Left-Turn (DLT) Intersections 8-17 8.4.2.1 Benefits • Motor Vehicle Right-Turns design flag: The design includes the protected intersection concept with corner refuge islands that tighten turn radii and extend physical protection for crossing pedestrians.
From page 178...
... 8-18 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges Flag Remaining Description Mode/Travel Path Motor Vehicle Right-Turns (Section 4.4.1) Channelized right-turn lanes can lead to high vehicle speeds.
From page 179...
... Displaced Left-Turn (DLT) Intersections 8-19 The core elements of the design are as follows: • As with the inside crossing concept, the median walk provides a single crossing of mainline through vehicle movements.
From page 180...
... 8-20 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges 8.4.3.1 Benefits This DLT intersection concept includes these benefits for bicyclists and pedestrians: • Multilane Crossings design flag: An inside crossing pedestrian mainline crossing minimizes crossing distance and exposure to vehicular traffic. A tapered median also allows for a relatively narrow median at the mainline crossing, to shorten the crossing distance.
From page 181...
... (continued on next page) Flag Remaining Description Mode/Travel Path Motor Vehicle RightTurns (Section 4.4.1)
From page 182...
... 8-22 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges Exhibit 8-22. Option for DLT crossing.
From page 183...
... Displaced Left-Turn (DLT) Intersections 8-23 speed, volumes, and number of lanes (though it is expected the crossing would be best served as a controlled movement)
From page 184...
... 8-24 Guide for Pedestrian and Bicyclist Safety at Alternative and Other Intersections and Interchanges 8.5.4 Bypass Lane Design If a bypass lane is used at a DLT intersection, there are two ways that DLT intersections have typically accommodated the geometry for the right-turn bypass lane to join back with the cross street through lanes. The choice between these two options will impact the pedestrian experience if pedestrians are walking along an inside path between travel lanes.
From page 185...
... Displaced Left-Turn (DLT) Intersections 8-25 8.6 References 1.

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