Traffic Signal Control Strategies for Pedestrians and Bicyclists (2022) / Chapter Skim
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From page 31... ...
31 This chapter describes the following nine treatments that address conflicts with turning traffic: C H A P T E R 6 Treatments that Reduce or Eliminate Conflicts with Turning Traffic Primary Function Section Treatment Name Separation from leftturning traffic 6.1 Protected-Only Left Turns to Address Non-motorized User Conflicts Separation from rightand left-turning traffic 6.2 Concurrent-Protected Crossings 6.3 Exclusive Pedestrian and Bicycle Phases 6.4 Channelized Right Turns/Delta Islands Partial separation from right-turning traffic 6.5 Leading Pedestrian Intervals 6.6 Delayed Turn/Leading Through Intervals 6.7 Pedestrian Overlaps with Leading Pedestrian Intervals and Vehicular Holds Preventing turns on red 6.8 No Turn on Red Encouraging turning traffic to yield 6.9 Flashing Pedestrian and Bicycle Crossing Warnings Turning vehicles are one of the greatest hazards facing pedestrians and bicycles at intersections. They have variously been estimated to represent 25%–50% of pedestrian crashes at intersections (Lord et al., 1998)
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From page 32... ...
32 Traffic Signal Control Strategies for Pedestrians and Bicyclists concurrently with parallel through traffic. The main drawback to this treatment is that it requires an exclusive right-turn lane as well as an exclusive left-turn lane.
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Treatments that Reduce or Eliminate Conflicts with Turning Traffic 33 6.1.1.2 Description and Objective Left-turning traffic is perhaps the greatest hazard that pedestrians and cyclists face at signalized intersections. A review of safety studies found that the proportion of pedestrian crashes at intersections that involved a left-turning vehicle was between 17% and 32% (Lord et al., 1998)
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From page 34... ...
34 Traffic Signal Control Strategies for Pedestrians and Bicyclists For crossing bicycles and pedestrians, risks involved with permitted left turns are especially high on multilane roads. For left-turning drivers on roads with only one through lane per direction, finding a gap requires less attention, and as a result, they are more likely to notice pedestrians and bicycles before beginning to turn.
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Treatments that Reduce or Eliminate Con icts with Turning Traf c 35 a platoon. Research done for this project found that le -turning drivers in the second or later position in a platoon were 56% less likely to yield to a crossing bicycle or pedestrian than drivers who were not immediately following another vehicle.
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From page 36... ...
36 Traffic Signal Control Strategies for Pedestrians and Bicyclists allowed on streets with one lane per direction; however, protected left turns are more common in practice, except from minor-street approaches that are too narrow to have left-turn lanes. In the United States, guidelines regarding the use of permitted left turns are comparatively less strict than in the Netherlands.
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Treatments that Reduce or Eliminate Conflicts with Turning Traffic 37 whose green duration becomes shorter. These impacts can be mitigated by using shorter cycles (see Section 7.1)
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38 Traffic Signal Control Strategies for Pedestrians and Bicyclists • If very heavy turning demand results in a short green window for bicycles, consider smallzone coordination to limit bicycle delay (see Section 9.2)
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Treatments that Reduce or Eliminate Conflicts with Turning Traffic 39 Hauer, E (2003, January)
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40 Traffic Signal Control Strategies for Pedestrians and Bicyclists 6.2.1.3 Variations Variations to this treatment arise from how the right-turn movement fits into the phasing plan. Wherever a right-turn movement has a parallel left-turn phase, it is efficient to run those turns concurrently.
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From page 41... ...
Treatments that Reduce or Eliminate Conflicts with Turning Traffic 41 This treatment also requires an exclusive right-turn lane. At intersections without exclusive right-turn lanes, it may be possible to create an exclusive right-turn lane by widening an intersection approach, converting a parking lane into a turn lane, or converting a shared throughright lane into an exclusive right-turn lane and adjusting signal timing accordingly.
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42 Traffic Signal Control Strategies for Pedestrians and Bicyclists concurrent-protected using split through phasing. The left lane was converted to an exclusive left-turn lane, leaving only one lane for through traffic.
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Treatments that Reduce or Eliminate Conflicts with Turning Traffic 43 150 vehicles per hour for one-way cycle tracks and recommend that two-way cycle tracks avoid all permitted conflicts (an increasing number of exceptions to this latter rule can be found in the Netherlands)
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44 Traffic Signal Control Strategies for Pedestrians and Bicyclists and conflicting right-turn lags (Phase 03)
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Treatments that Reduce or Eliminate Conflicts with Turning Traffic 45 6.2.4.4 Geometric Elements Concurrent-protected crossings require exclusive right-turn lanes. In some cases, a through lane can be converted into a right-turn lane while still providing sufficient through capacity.
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From page 46... ...
46 Traffic Signal Control Strategies for Pedestrians and Bicyclists 6.3.1.4 Operating Context There are several contexts for which exclusive pedestrian or bicycle phases might be appropriate: • Where either high-speed right turns, a high volume of right turns, or frequent right-turning trucks make concurrent crossings unsafe, and it is not possible to provide a dedicated rightturn lane; • At intersections with very high pedestrian-volumes -- as might be common near a busy transit station -- where concurrent crossings would conflict with right-turning traffic to the point of creating tension and/or overly restricting right-turn capacity; • At intersections with very high pedestrian-volumes -- where pedestrians need the green for a large part of the cycle -- by combining an exclusive pedestrian phase with concurrent crossings (see Exhibit 6-10[c]
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From page 47... ...
Treatments that Reduce or Eliminate Con icts with Turning Traf c 47 crossings. However, several years ago, the city retimed its signals for a crossing speed of 3.5 /s instead of 4 /s, and diagonal crossings were formally removed to avoid having to lengthen pedestrian phases.
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From page 48... ...
48 Traffic Signal Control Strategies for Pedestrians and Bicyclists Green." The main impetus for applying this treatment has been to protect cyclists from conflicts with turning traffic. Where it has been applied in Groningen, it has eliminated fatal bicycle–motor vehicle collisions; bicycle–bicycle conflicts, which are resolved without formal rules, have not been a safety problem.
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From page 49... ...
Treatments that Reduce or Eliminate Conflicts with Turning Traffic 49 6.3.3.2 Guidance The Toronto Transportation Division developed the following guidelines for implementing exclusive pedestrian phases. The treatment should be implemented only if one or more of the following conditions are satisfied (Kattan et al., 2009)
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From page 50... ...
50 Traffic Signal Control Strategies for Pedestrians and Bicyclists 6.3.4.4 Geometric Elements If bicycles will be allowed to use an exclusive phase with pedestrians, it is preferable for the intersection to be configured so that the paths of bicycles and cross-direction pedestrians meet outside the crosswalks that are regulated by traffic signals. An example of this is when bicycles are in a shared-use path or in protected bike lanes offset far enough from the curb that pedestrians have a waiting platform between the curb and the protected bike lane.
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Treatments that Reduce or Eliminate Conflicts with Turning Traffic 51 Chapter 10)
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From page 52... ...
52 Traffic Signal Control Strategies for Pedestrians and Bicyclists 6.4.2 Applications and Expected Outcomes 6.4.2.1 National and International Use In the U.S., channelized right turns are common, particularly on wide, higher speed roads. Most were not made for the benefit of pedestrians or bicyclists but rather to reduce motorist delay by increasing turning speed.
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From page 53... ...
Treatments that Reduce or Eliminate Conflicts with Turning Traffic 53 cyclist intends to turn into the crossing. Eliminating those channelized right turns could free up enough space to create a protected intersection layout in which the shared-use path is offset several feet from the road, improving visibility between bicycles and right-turning vehicles.
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From page 54... ...
54 Traffic Signal Control Strategies for Pedestrians and Bicyclists 6.4.3 Considerations 6.4.3.1 Accessibility Considerations APS must be carefully installed and adjusted when used at channelized right turns (see MUTCD, Section 4E.13)
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From page 55... ...
Treatments that Reduce or Eliminate Conflicts with Turning Traffic 55 6.4.4.2 Phasing and Timing Where channelized right turns are signalized, it makes the pedestrian -- and sometimes bicycle -- crossings multistage, which can result in long delays unless signals are timed for good progression for crossing pedestrians and cyclists. This is a challenge because four different streams of pedestrian movements cross any given channelized right-turn lane (i.e., people walking northbound, southbound, eastbound, and westbound)
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56 Traffic Signal Control Strategies for Pedestrians and Bicyclists phase runs. In addition, the timing gives bicycles two progression windows per cycle.
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Treatments that Reduce or Eliminate Conflicts with Turning Traffic 57 Bachiochi, J., & Furth, P
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58 Traffic Signal Control Strategies for Pedestrians and Bicyclists 6.5.1.4 Operating Context An LPI might be appropriate where pedestrian crossings are concurrent with a parallel vehicular phase, where right turns (in this report, "right turns" also includes left turns from a one-way street) are permitted to conflict with crossings, and the following four criteria are met: 1.
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Treatments that Reduce or Eliminate Conflicts with Turning Traffic 59 the needed length of an LPI, engineers identify the conflict zone (i.e., the area where pedestrians and turning cars conflict) and measure two distances (see Exhibit 6-19)
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From page 60... ...
60 Traffic Signal Control Strategies for Pedestrians and Bicyclists To illustrate the method, suppose dPed = 14 ft and dRT = 45 ft. Using the suggested speeds given earlier, tPed = 14/3.5 = 4.0 s, while tRT = 45/15 = 3.0 s.
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Treatments that Reduce or Eliminate Conflicts with Turning Traffic 61 A comparison of 26 intersections in New York State found that LPIs reduced pedestrian crashes with turning vehicles by 28%; the reduction was 64% after adjusting for crash severity (King, 2000)
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62 Traffic Signal Control Strategies for Pedestrians and Bicyclists the cost of the treatment is nominal, and for pedestrian phases that are actuated, there will be an impact to traffic only when the pedestrian phase is called. Furthermore, as explained earlier, LPI is appropriate where the conflicting turning volume is moderate or low but not where it is high.
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From page 63... ...
Treatments that Reduce or Eliminate Conflicts with Turning Traffic 63 motorists -- including median islands, raised centerlines, and in-street Yield to Pedestrians signs -- can also be helpful in this regard. 6.5.4 Implementation Support 6.5.4.1 Equipment Needs and Features Nearly all controllers manufactured after 2005 are programmed to allow LPIs, so no special equipment is needed.
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From page 64... ...
64 Traffic Signal Control Strategies for Pedestrians and Bicyclists Manual on Uniform Traffic Control Devices for Streets and Highways.
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Treatments that Reduce or Eliminate Conflicts with Turning Traffic 65 (a) During LTI (b)
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66 Traffic Signal Control Strategies for Pedestrians and Bicyclists during the leading interval, and a circular green is displayed during the permitted-turn interval (see Exhibit 6-22)
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Treatments that Reduce or Eliminate Conflicts with Turning Traffic 67 the intersections where it is used have only pedestrian crossings; however, it is also used where there are bicycle crossings. In New York City, delayed turn has been used since approximately 2015 -- usually with a 10 s leading through interval -- and always in conjunction with FYA during the permitted-turn interval.
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68 Traffic Signal Control Strategies for Pedestrians and Bicyclists 2016)
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Treatments that Reduce or Eliminate Conflicts with Turning Traffic 69 If turns are from an exclusive lane, then delayed turn should not affect the delay for any movements other than the turns that are held during the leading interval. If turns are from a shared through-turn lane, as in Montreal, then a small amount of additional delay to through traffic should be expected, increasing with the volume of turning traffic.
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70 Traffic Signal Control Strategies for Pedestrians and Bicyclists If a state's vehicle code is consistent with this section of the MUTCD in prohibiting turns when the only signal displayed is a green arrow, then the display used in Montreal (a through green arrow without any red arrows) should be sufficient, although an effort may be warranted to promote driver understanding and compliance.
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Treatments that Reduce or Eliminate Conflicts with Turning Traffic 71 Bibliography Furth, P G., & Saeidi Razavi, R
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72 Traffic Signal Control Strategies for Pedestrians and Bicyclists LPI to count as part of the pedestrian phase end buffer, which enables the pedestrian phases to have a longer Walk interval compared to ending FDW at the start of the yellow. This reduces pedestrian delay and creates additional crossing opportunities for slower pedestrians.
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From page 73... ...
Treatments that Reduce or Eliminate Conflicts with Turning Traffic 73 In the Netherlands, where pedestrian and bicycle phases are programmed as independent phases rather than as children of a vehicular phase, pedestrian overlaps with full and partial vehicular holds occur frequently. An example of an overlap with a partial vehicular hold is in Amsterdam, at the junction of Nobelweg (considered the north–south street)
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74 Traffic Signal Control Strategies for Pedestrians and Bicyclists 4. Lengthening pedestrian phases, reducing delay, and helping slower pedestrians.
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Treatments that Reduce or Eliminate Conflicts with Turning Traffic 75 6.7.4 Implementation Support 6.7.4.1 Equipment Needs and Features Not applicable for this treatment. 6.7.4.2 Phasing and Timing As an example of how pedestrian phases might be programmed as overlaps, consider the example in Exhibit 6-25(b)
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From page 76... ...
76 Traffic Signal Control Strategies for Pedestrians and Bicyclists right -- even when the crossing person is directly in front of the vehicle -- creating a high-risk situation, especially for pedestrians or bicycles with a low profile such as children and people in wheelchairs. 6.8.1.3 Variations Some states allow left turns on red from a one-way street to another one-way street.
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From page 77... ...
Treatments that Reduce or Eliminate Conflicts with Turning Traffic 77 A review of Fatality Analysis Reporting System data showed that in the 10-year period between 1982 and 1992, less than 1% of all national traffic fatalities involved a right-turning vehicle at an intersection that permits RTOR; however, bicyclists or pedestrians were involved in more than half of those fatal crashes (NHTSA, 1994)
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From page 78... ...
78 Traffic Signal Control Strategies for Pedestrians and Bicyclists • An unacceptable number of pedestrian conflicts with RTOR maneuvers, especially if they involve children, older pedestrians, or persons with disabilities; and • More than three RTOR crashes reported in a 12-month period for that particular approach. The MUTCD also provides guidance for the design of various types of NTOR regulatory signs.
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From page 79... ...
Treatments that Reduce or Eliminate Conflicts with Turning Traffic 79 6.8.4.4 Geometrics This treatment can be applied with and without exclusive right-turn lanes. NTOR is an effective countermeasure when (1)
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80 Traffic Signal Control Strategies for Pedestrians and Bicyclists 6.9.1.3 Variations FYA is the only commonly used flashing warning in the U.S. FYA is widely used to warn leftturning motorists of potential conflicts with oncoming traffic.
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From page 81... ...
Treatments that Reduce or Eliminate Conflicts with Turning Traffic 81 A flashing right-hook warning is also used at one intersection approach in Amsterdam. Its graphics are based on a commonly used static pedestrian/bicycle crossing warning sign.
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82 Traf c Signal Control Strategies for Pedestrians and Bicyclists Source: Boot et al.
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Treatments that Reduce or Eliminate Conflicts with Turning Traffic 83 (i.e., conflicts that required substantial braking or course adjustments by one or both vehicles) was even more pronounced (Andersen, 2015)
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From page 84... ...
84 Traffic Signal Control Strategies for Pedestrians and Bicyclists 6.9.4.3 Signage and Striping Not applicable for this treatment. 6.9.4.4 Geometric Elements Not applicable for this treatment.
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