Traffic Signal Control Strategies for Pedestrians and Bicyclists (2022) / Chapter Skim
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Pages 85-114
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From page 85... ...
85 This chapter describes six treatments aimed at reducing delay for pedestrians and bicycles and accommodating slower pedestrians, grouped by their primary function: C H A P T E R 7 Treatments that Reduce Pedestrian and Bicycle Delays Primary Function Section Treatment Name Reduce effective red time 7.1 Short Cycle Length 7.2 Reservice Increase effective green time for pedestrians and bicycles 7.3 Maximizing Walk Interval Length 7.4 Pedestrian Clearance Settings for Better Serving Slower Pedestrians Limit impact to other road users while serving pedestrians 7.5 Pedestrian Recall versus Actuation 7.6 Pedestrian Hybrid Beacons Additional treatments for reducing delay are found in Chapter 9 (treatments focused solely on cyclist delay) and Chapter 10 (treatments for multistage crossings)
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86 Traffic Signal Control Strategies for Pedestrians and Bicyclists reduce pedestrian delay and make crossings accessible to pedestrians with lower walking speeds. National and local standards specify a minimum Walk interval length (usually 7 s)
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Treatments that Reduce Pedestrian and Bicycle Delays 87 green constraints. This allows the intersection to cycle as quickly as possible for the current level of traffic, automatically lengthening cycles when traffic is heavy and shortening them when traffic is light.
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88 Traffic Signal Control Strategies for Pedestrians and Bicyclists conflicting traffic. This leads to preference for fully actuated control at most intersections (S. Linders, personal communication, 2018)
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Treatments that Reduce Pedestrian and Bicycle Delays 89 pedestrian phase, or use a shorter cycle in which the minor street is given only the time needed to serve vehicles. In the latter case, when there is a pedestrian call, the minor-street phase runs beyond its scheduled time, and the controller then has to transition over the next one or two cycles to return the intersection to coordination.
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90 Traffic Signal Control Strategies for Pedestrians and Bicyclists There can be some tension between the desire to keep cycles short and the desire to protect pedestrians from turning conflicts using such techniques as exclusive pedestrian phases (see Section 6.3) and leading pedestrian intervals (LPIs)
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Treatments that Reduce Pedestrian and Bicycle Delays 91 Some controllers have special features that can reduce phase lengths and sometimes reduce cycle lengths. Sobie et al.
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92 Traf c Signal Control Strategies for Pedestrians and Bicyclists 7.2.1.2 Description and Objective Reservice refers to serving a tra c movement two or more times within a signal cycle. Reservice can be applied to bicycle and pedestrian crossings to reduce their delay as well as to right- and le -turn movements to limit their delay when they are converted to protected-only phasing, with the goal of improving the safety of a bicycle/pedestrian crossing.
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Treatments that Reduce Pedestrian and Bicycle Delays 93 7.2.2 Applications and Expected Outcomes 7.2.2.1 National and International Use Reservice is a well-known technique, although its application is relatively uncommon. It is sometimes used for transit signal priority; for left turns whose turn bay is too short to store the full left-turn demand of a cycle; and for pedestrians and bicycles as well.
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94 Traf c Signal Control Strategies for Pedestrians and Bicyclists 7.2.3.2 Guidance Not applicable for this treatment. 7.2.3.3 Relationships to Relevant Treatments Where crossings of channelized right turns (see Section 6.4)
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Treatments that Reduce Pedestrian and Bicycle Delays 95 Bibliography Furth, P
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96 Traffic Signal Control Strategies for Pedestrians and Bicyclists If the concurrent vehicular phase is actuated, the formula is given in Equation 7-3: ( )
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Treatments that Reduce Pedestrian and Bicycle Delays 97 then minimum green can be increased with little impact. A suggested rule of thumb is to set the minimum green equal to the 30th percentile green time for the relevant period of the day, then adjust the Walk interval based on Equation 7-3.
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98 Traffic Signal Control Strategies for Pedestrians and Bicyclists Still, many cities do not routinely apply Rest in Walk or maximize the Walk interval for non-coordinated phases. Often, a default Walk interval length (usually 7 s)
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Treatments that Reduce Pedestrian and Bicycle Delays 99 7.3.3.3 Relationships to Relevant Treatments With most controllers, the Rest in Walk setting automatically applies pedestrian recall (see Section 7.5) to coordinated phases.
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100 Traffic Signal Control Strategies for Pedestrians and Bicyclists Urbanik, T., Tanaka, A., Lozner, B., Lindstrom, E., Lee, K., Quayle, S., Beaird, S., Tsoi, S., Ryus, P., Gettman, D., Sunkari, S., Balke, K., & Bullock, D
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Treatments that Reduce Pedestrian and Bicycle Delays 101 where tcl,needed = primary pedestrian clearance time needed (s) ; D = crosswalk length, curb to curb ( )
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102 Traffic Signal Control Strategies for Pedestrians and Bicyclists where W = length of the Walk interval (s) ; FDW = length of the FDW interval (s)
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Treatments that Reduce Pedestrian and Bicycle Delays 103 Likewise, some agencies do not allow yellow or red clearance times to count toward needed pedestrian clearance time, which forces the FDW to be longer. This restriction is similar to lowering the pedestrian clearance speed in that it gives pedestrians more time to cross; however, unlike lowering clearance speed, this restriction adds time to the end of the phase that cannot be counted on to serve pedestrians.
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104 Traffic Signal Control Strategies for Pedestrians and Bicyclists the signal cycle to be longer, which can increase pedestrian delay (see Section 7.1) and make it less feasible for pedestrian phases to be on recall (see Section 7.5)
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Treatments that Reduce Pedestrian and Bicycle Delays 105 the cycle length at 90 s. As restrictions are relaxed, the Walk interval increases in length from 10 to 16 s, with corresponding reductions in pedestrian delay.
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106 Traffic Signal Control Strategies for Pedestrians and Bicyclists 7.4.4.3 Signage and Striping Not applicable for this treatment. 7.4.4.4 Geometric Elements Shorter crossings, which might be designed using corner bulb-outs, require less clearance time, making signals more efficient and improving accessibility.
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Treatments that Reduce Pedestrian and Bicycle Delays 107 pedestrian demand is large enough that there is a call for service in most cycles, as seen on the horizontal axis with total number of pedestrians (for both pedestrian crossings, unless cross streets are on split phase) per cycle.
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108 Traffic Signal Control Strategies for Pedestrians and Bicyclists associated with a non-coordinated phase are usually actuated, but they may be set to recall where pedestrian demand is high. For example, Boston's policy is to apply pedestrian recall for a crossing if pedestrians are present for at least 50% of the cycles (City of Boston, 2013)
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Treatments that Reduce Pedestrian and Bicycle Delays 109 7.5.3.2 Guidance The NACTO Urban Street Design Guide recommends using pretimed signals in urban areas, which results in pedestrian phases being on recall. STM2 indicates that pedestrian recall may be used at locations and/or times with high pedestrian-volumes.
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110 Traf c Signal Control Strategies for Pedestrians and Bicyclists Urbanik, T., Tanaka, A., Lozner, B., Lindstrom, E., Lee, K., Quayle, S., Beaird, S., Tsoi, S., Ryus, P., Gettman, D., Sunkari, S., Balke, K., & Bullock, D
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From page 111... ...
Treatments that Reduce Pedestrian and Bicycle Delays 111 • Crossings of high speed (e.g., 35 mph or more) and high-volume two-lane roadways; • Locations where local-street bicycle routes (also called bicycle boulevards and neighborhood greenways)
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112 Traffic Signal Control Strategies for Pedestrians and Bicyclists of 21 PHBs in Tucson, AZ, found that total crash rate and pedestrian crash rate were reduced by 35% and 86%, respectively. During the same before-and-after analysis, a control group of 36 signalized intersections saw a 16% reduction in both total crashes and pedestrian-related crashes, and a control group of 102 unsignalized intersections saw a 9% reduction in total crash rate and a 143% increase in pedestrian crash rate, indicating the effectiveness of PHBs in improving pedestrian safety, especially compared to unsignalized crossings (Fitzpatrick & Park, 2010)
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Treatments that Reduce Pedestrian and Bicycle Delays 113 The MUTCD's recommendations on pedestrian pushbutton location should be followed. Detectable warning surfaces and ADA-accessible curb ramps that apply at signalized crossings apply equally with PHBs.
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114 Traffic Signal Control Strategies for Pedestrians and Bicyclists This helps prevent vehicles in one lane from screening pedestrians from drivers in other lanes during the flashing red interval, in which vehicles are allowed to advance. 7.6.4.4 Geometric Elements Not applicable for this treatment.
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