Decision-Making Guide for Traffic Signal Phasing (2020)

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47 7 Pedestrian Phasing While pedestrians are more prevalent at some traffic signals than others, signalized intersections should be configured to accommodate pedestrians where pedestrian traffic is permitted and reasonably foreseeable. Pedestrians can be served using either of two types of signal indications: • Pedestrian signal indications, which display a walking person (symbolizing WALK) or an upraised hand (symbolizing DONT WALK). • Vehicular signal indications, where pedestrians are guided by signal indications also used by vehicular traffic. Where vehicular signal indications are used to control pedestrian traffic, the indications must provide clear guidance to pedestrians crossing in both directions about the appropriate time to cross. For instance, intersections with protected-permissive or protected-only left-turn phasing mode usually cannot provide this clear guidance. No matter which type of signal indications are used to serve pedestrians, signals must provide a sufficient time for pedestrians to cross the street and a way for pedestrians to call for a crossing phase. Pedestrian signal timing provisions can be found in the MUTCD. 7.1 Pedestrian Phasing Types Pedestrians are normally served by one of two signal phasing treatments: • Concurrent phasing, where pedestrians are directed to cross a street at the same time as the parallel vehicle movements. When concurrent phasing is used, parallel permissive right turns and parallel permissive left turns conflict with (and must yield to) pedestrians. Conflicts can be avoided by using protected-only phasing mode for conflicting left and right turns. When all conflicting turns use protected-only phasing mode, the pedestrian movement is sometimes called Protected or Protected yet Concurrent. • Exclusive phasing, where a portion of the traffic signal cycle is reserved solely for pedestrians to cross, usually in any direction, while all vehicle movements have a red indication. Exclusive phasing, shown in Figure 16 and sometimes called a “Barnes Dance” or “Pedestrian Scramble,” eliminates conflicts between vehicular and pedestrian movements. A 2012 New York study showed that exclusive pedestrian phasing reduced vehicle-pedestrian crashes by 51 percent, although the same study showed a 10 percent increase in other vehicular crash types (Chen et al. 2012). Although near-miss conflicts are difficult to quantify, exclusive pedestrian phasing, in theory, also reduces near-miss conflicts, which typically occur more frequently than pedestrian crashes. At an intersection with exclusive pedestrian phasing, pedestrians can either be permitted or prohibited from crossing during the concurrent vehicular phases. The former option introduces conflicts between pedestrians and turning vehicles, but the latter option requires pedestrians to

48 wait longer to be served, possibly contributing to pedestrian crossing violations. In both options, exclusive pedestrian phasing tends to degrade traffic operations because all traffic is stopped while pedestrians are served. Figure 16 – Typical Phasing Diagram for Exclusive Pedestrian Movement (NCHRP 2008) Exclusive phasing is uncommon, but it may be appropriate at urban intersections with high volumes of both pedestrians and turning traffic. A threshold of 1,200 pedestrian crossings per day, when considering pedestrians on all legs of an intersection, has been identified above which exclusive pedestrian phasing may offer a safety benefit over concurrent phasing (FHWA 1983; FHWA 2002). Right turns on red are often (but not always) prohibited at intersections with exclusive pedestrian phasing to ensure that no traffic movements cross pedestrians’ paths, but the RTOR prohibition can even further degrade operational performance. When static full-time RTOR restrictions are used, rights on red are prohibited during all portions of the cycle, even phases other than the exclusive pedestrian phase, when rights on red may be safe. Rights on red can also be prohibited only during an exclusive pedestrian phase using a blank-out sign, but this increases complexity, cost, and maintenance commitment. The MUTCD recommends that APS should be considered at intersections with exclusive pedestrian phasing to communicate when to cross to vision-impaired pedestrians, since it is not possible to use the sound of traffic as a guide. APS is a critical tool to inform vision-impaired pedestrians of the appropriate time to cross. 7.1.1 Pedestrian Prohibition It is also possible to prohibit pedestrians across one or more legs of an intersection. However, pedestrian prohibitions should be used sparingly. A pedestrian prohibition on even one leg of an intersection can significantly increase pedestrians’ travel time and traffic exposure. If a pedestrian is prohibited from crossing a desired leg of a typical intersection, the pedestrian would need to cross all three remaining legs to accomplish the same movement, usually at a high cost of delay, redundant travel distance, and exposure to potential conflicts on the other three legs. Furthermore, pedestrian compliance is often poor if pedestrians feel the prohibition is unreasonable.

49 The prohibition of pedestrians on an intersection leg cannot be accomplished solely by a lack of crosswalk markings and a lack of pedestrian signal indications. In most states, a legal crosswalk exists at every intersection, across every approach, even if unmarked. The MUTCD recommends No Pedestrian Crossing (R9-3) signs when pedestrians are prohibited on intersections legs without “a barrier or other physical feature to physically prevent the pedestrian movements” (FHWA 2009b). 7.1.2 Leading Pedestrian Interval A LPI can be considered a middle ground between exclusive and concurrent pedestrian phasing. During an LPI, shown in Figure 17, pedestrians are given a WALK signal at least 3 seconds prior to the green indication for parallel vehicular movements, allowing pedestrians to get a head start to cross the street. When pedestrians start crossing on an LPI, the start of their crossing feels the same as an exclusive pedestrian phase (albeit without the diagonal crossings), since all motor vehicle movements are stopped. Pedestrians can establish themselves in the crossing and become more visible to conflicting turning motorists during the LPI, promoting safety. An LPI provides much better traffic operational characteristics than an exclusive pedestrian phase, because it lasts for only a few seconds rather than the length of the entire pedestrian phase. However, pedestrian-vehicle conflicts do exist with an LPI, unlike in an exclusive pedestrian phase. Figure 17 -Typical Phasing Diagram for LPI ( NCHRP 2008) A 2009 Pennsylvania study found that LPIs reduce vehicle-pedestrian crashes by about 59 percent, (Fayish and Gross 2010) suggesting strong safety benefits. The MUTCD recommends that an LPI be at least 3 seconds in duration, (FHWA 2009b) and most LPIs range from 3 to 7 seconds long. However, some agencies have used longer LPIs, sometimes more than 20 seconds. As an LPI increases in duration, an intersection’s operations begin to more closely match that of an exclusive pedestrian phase, both in terms of pedestrian comfort and motorist delay. Some intersection characteristics are more suited than others to the use of an elongated LPI (Dittberner and Vu 2017). If an LPI is used, the MUTCD recommends considering turn prohibitions across the crosswalk during the LPI (FHWA 2009b). An LPI may not be effective if it occurs when RTOR movements cross the pedestrian

50 path. Some turns are prohibited by the red signal indications, but RTOR may need particular attention. Where a dedicated right-turn lane exists, right-turn prohibitions during an LPI can be accomplished using a separate right-turn signal face that includes a right-turn steady red arrow during the LPI. Right turns can also be accommodated by serving the pedestrian crossings during the first part of the parallel through vehicular phase and allowing uninterrupted turning movements after the pedestrian crossing and clearance intervals have been terminated during a later part of the vehicular phase. LPIs are not normally used where the parallel vehicular movement is served by leading protected- permissive left turns. In this case, the LPI would follow the protected left-turn phase and precede the through movement, which could introduce confusion for left-turning motorists. The MUTCD recommends that APS should be considered at crossings with an LPI to communicate to pedestrians with vision impairment (FHWA 2009b). Another way to accommodate vision-impaired pedestrians at a crossing with an LPI is to provide the minimum WALK time when measured from the start of the parallel vehicular through movement. For example, at a crossing with a 3-second LPI and a 7-second minimum WALK interval, a WALK interval of at least 10 seconds would appropriately accommodate vision- impaired pedestrians. 7.2 Pedestrian Detection Two methods can be used to accommodate pedestrians at traffic signals: • In an actuated pedestrian phase, the signal provides a WALK indication only during cycles when a pedestrian has been detected. The most common method of detecting pedestrians is a pushbutton. However, passive pedestrian detection (also known as automatic pedestrian detection) is sometimes used, avoiding the need for a pushbutton press (or to supplement a pushbutton). Passive detection uses technologies such as video, microwave, or thermal to identify the presence of a pedestrian waiting to cross. While passive detection can produce some false calls and missed calls, it overcomes the typically large segment of pedestrians who do not press the pushbutton. Actuated pedestrian crossings are normally used on crossings with a low volume of pedestrians and a low volume of parallel through vehicles, and where serving a pedestrian phase every cycle would significantly degrade intersection operations. These conditions typically exist at wide suburban intersections. Actuated pedestrian crossings should also be used at traffic signals where the parallel vehicular through movement is actuated, such that it is only served when a vehicle is detected. • In pedestrian recall operation, pedestrian crossings are assumed to occur on every signal cycle, and the signal should provide sufficient time for pedestrians to cross on every cycle. Pedestrian recall provides better pedestrian comfort and convenience than actuated operation. It is most commonly used in urban areas with concurrent pedestrian phasing and a volume of pedestrians so high that pedestrians cross on most signal cycles. The City of El Cerrito, Calif., recommends

51 pedestrian recall when pedestrians cross on at least 75 percent of signal cycles for three or more hours per day (City of El Cerrito 2016). Pedestrian pushbuttons are currently not required when a crossing always operates on pedestrian recall, reducing construction and maintenance costs. However, if adopted, the Public Right-of- Way Accessibility Guidelines (PROWAG) proposes to require APS pushbuttons at all signalized pedestrian crossings (including those using pedestrian recall) to communicate with vision- impaired pedestrians. If PROWAG is adopted, APS pushbuttons will be required for new construction or retrofits. Some agencies are already providing APS pushbuttons at all new signals in anticipation of PROWAG adoption in its current form. It is not necessary to use the same detection type at every crossing at a signalized intersection. In fact, where a low-volume street crosses an arterial, it is likely that the pedestrian crossings of the minor street can operate on pedestrian recall, since the pedestrian movement across the narrow minor street occurs at the same time that the high-volume major street is served. Pedestrian recall on these crossings typically does not degrade traffic operations. In contrast, pedestrian crossings of the major street occur at the same time as low-volume minor street movements with little green time. These movements are usually actuated, because pedestrian recall would delay the high-volume major street traffic unnecessarily when pedestrians are not present. A crosswalk with pedestrian pushbuttons can also operate in pedestrian recall mode. For instance, an intersection may be timed such that pedestrian recall does not disrupt operations during peak and midday periods, but a change in traffic patterns at night and a reduction of pedestrian volume make pedestrian recall disruptive at that time. This is a preferred operating strategy where possible, because it provides the comfort and convenience of pedestrian recall at key times of day and provides a pushbutton for pedestrian actuation at other times. 7.3 Two-Stage Crossing Long pedestrian crossings require long pedestrian crossing durations, which may take green time away from higher-volume traffic movements and create unreasonably long intersection delays. It is sometimes useful to time a crossing to allow pedestrians to cross only half the street at a time, to a sufficiently sized median refuge area with pedestrian pushbuttons. Pedestrians are expected to wait in the median until the next cycle, when they can complete their crossing. The two-stage crossing, depicted in Figure 18, allows for much shorter clearance intervals for pedestrians which is often a major factor in green splits and ultimately cycle length. A two-stage crossing should only be considered when the median refuge area is at least 10 feet wide. Wider medians are desirable for streets with higher speeds (40 mph or higher) to provide a greater level of pedestrian comfort while waiting in the median. While a two-stage crossing can reduce the pedestrian clearance time and improve traffic operations, it should usually be used as a last resort. It is usually unreasonable to expect a pedestrian to wait in the median for an entire signal cycle, and observations have revealed that many pedestrians do not wait in

52 the median for the next signal cycle, which creates unanticipated conflicts. Two-stage crossings significantly increase pedestrians’ delay in crossing a street. However, two-stage crossings can be valuable at unconventional intersections or interchanges such as a SPUI. At a typical SPUI with three signal phases, all the phases conflict with pedestrians crossing the entire street in one stage. A pedestrian crossing can be implemented without increasing the number of phases by allowing pedestrians to cross halfway across the street during one left-turn phase and the rest of the way across during another left-turn phase. At signals that serve only pedestrian crossings, such as midblock locations, a two-stage offset crossing can help promote both pedestrian safety and traffic operations by stopping only half the street at a time. The signal timing can be set to minimize the delay to crossing pedestrians, and the crossing can reduce motorist delay by about half. A two-stage crossing can help provide two-way corridor signal progression, since each direction can be synchronized separately. A raised median island with pedestrian barriers and an accessible path is essential to distinguish the two crossings, and unless the median is sufficiently wide (at least 24 feet), the crossings should be offset longitudinally from each other along the roadway to ensure that pedestrians are not led to believe they can cross the entire roadway in one signal cycle, and preclude the chance that a pedestrian may be looking at the wrong pedestrian signal at the crossing. Offsetting the two crossings can help to eliminate these concerns but may be difficult to accomplish at intersections. Figure 18 - Two-Stage Pedestrian Crossing