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22 CHAPTER 4 Review of Pedestrian Signal Warrant This chapter summarizes the research team's review and traffic signal. A secondary factor is walking speed, which is critique of the existing MUTCD pedestrian traffic signal war- used to adjust pedestrian volumes. rant. Details on reviews conducted on the pedestrian signal Despite the wide range of factors included in the current warrant are included in the following appendixes: pedestrian signal warrant, other factors could be considered. For example, a correlation between acceptable gap criteria and · Appendix G summarizes international signal warranting factors such as pedestrian age, pedestrian vision (and walking) practices. abilities, vehicle speed, and roadway cross section is reasonable. · Appendix H summarizes the basis for and use of the Also, the warrant does not mention safety considerations. Par- MUTCD pedestrian signal warrant. ticularly critical to this project, there is no consideration of · A workshop was held to explore the use of engineering judg- pedestrian generators, such as transit stops, within the war- ment in evaluating intersections to determine if a signal ranting criteria. There are also no allowances for pedestrian should be considered. The details of the workshop efforts are volumes that could result from the installation of pedestrian- documented in Appendix I. friendly treatments. Pedestrian delay is the measure used in the HCM (23) to determine the level of service for pedestrians. Delay is not directly considered in the signal warrant; however, The recommendations for changes to the pedestrian signal it relates to other variables such as pedestrian volume and gaps. warrant submitted to the National Committee on Uniform Other attributes of the warrant could be a reference to Traffic Control Devices in June 2005 and January 2006 are in alternative means of traffic control and how to determine the Appendix B. The development of those recommendations, size of the adequate gap length. The guidance section of the along with the pedestrian treatment guidelines (which use the MUTCD could be expanded to note that if a signal is not war- signal warrant criteria as part of the guidelines) is discussed ranted, then less restrictive controls may be appropriate, for in Appendix O. A summary of the critique of the MUTCD example, in-roadway warning lights. Information on how to pedestrian signal warrant follows. calculate critical gaps could provide the user with the pre- ferred method for determining the value. The Highway Capacity Manual has a method to calculate critical gap for a Review of Current Pedestrian single pedestrian or a group critical gap in Chapter 18 and Signal Warrant could be referenced (23). The current MUTCD pedestrian signal warrant (War- The following summarizes the key factors introduced rant 4) has many factors to be considered when evaluating above. Additional details are provided in Appendix H. whether or not a signal is warranted. For this TCRP/NCHRP project, these factors were split into three levels: primary Primary and Secondary Factors factors, secondary factors, and not related to current research study. These levels reflect the type of requirement Primary and secondary factors include the following: as indicated in the language of the MUTCD and the rele- vance to the issue being studied. Primary factors must be · Vehicular Gap. The gap criterion was introduced in 1988. considered and include available vehicular gaps (based on The criterion was derived from ITE's school crossing critical gap), pedestrian volume, and distance to the nearest guidelines (dating back to 1962). The guidelines were based
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23 on an old but common traffic signal timing scheme of fixed assumes a high number of vehicles on the major road; 60-s cycles. It is very difficult to maintain 60-s cycle lengths however, it does demonstrate a difference between vehicles because of pedestrian phasing and left-turn phasing. and pedestrians. · Pedestrian Volume. The current pedestrian volumes are · Distance to Nearest Traffic Signal. The current warrant higher than most of the previous research recommenda- includes a provision that a signal shall not be considered at tions, which were developed based on different factors. locations within 300 ft (91 m) of another signal. This is Comparing the pedestrian volumes included in Warrant 4 believed to be based on the distance a pedestrian will walk with the vehicular volumes in other warrants reveals some in order to cross the major street. The researchers did not interesting trends. Warrant 2 considers minor road traffic identify data that support this distance or other distances volume for 4 hours, while Warrant 3 considers minor road of how far beyond the desired path a pedestrian would be traffic volume for the peak hour. Warrant 4, which uses willing to walk. The U.S. DOT's 1995 Nationwide Personal pedestrian values, also includes peak hour and 4-hour cri- Transportation Survey did find that most pedestrian trips teria. A difference is that only one "minor approach" value (73 percent) are 0.5 mi (0.8 km) or less (3). With most trips is provided in Warrant 4 rather than the sliding scale pres- being about 2,600 ft (792 m), pedestrians might not be ent in Warrants 2 and 3. In other words, as the major street willing to increase their trip length by more than 10 per- volume increases in Warrants 2 and 3, the needed minor cent in order to walk to a different crossing location. As street volume to warrant a signal decreases. For the pedes- part of the on-street pedestrian surveys documented in trian warrant, a single "minor approach" value is provided. Appendix K, those interviewed were asked "if this crossing A second difference is that the vehicle warrants include a was not here, would you walk to the next intersection reduction factor for population and major roadway speed (point to intersection of interest)?" For three of the sites, only while the pedestrian warrant does not. Another difference about 25 percent of the respondents would walk to a sig- is the minimum number of vehicles or pedestrians needed nalized intersection at 550, 950, or 1,000 ft (168, 290, or to warrant a signal. A comparison of the lower threshold 305 m). For the site with a signalized intersection about volumes is shown in Table 10. For example, an intersection 200 ft (61 m) from the crossing, about 50 percent of those with only 100 vehicles for the peak hour would warrant interviewed would walk to that crossing. The remaining a signal before a midblock location with 143 pedestrians site where this question was appropriate did not follow per hour. When the 70 percent factor is used, the differ- similar findings. A much higher percentage indicated that ence becomes even more pronounced. An intersection they would be willing to walk to another crossing. Over could warrant a signal with only 75 vehicles while 143 65 percent of the respondents indicated that they would walk pedestrians would still be required. This comparison 600 ft (183 m) to cross at a signalized crossing. The greater Table 10. Comparison of vehicle and pedestrian threshold values. Lower Threshold Volume (Pedestrian or Vehicle on Highest Volume Number of Minor Road Approach) Lanes on Condition Peak Hour Four Hour Minor Road Warrant 3 b Warrant 4 c Warrant 2 d Warrant 4 e Approach Vehicular Pedestrian Vehicular Pedestrian (vph) (ped/h) (vph) (ped/h) 2 or more 150 115 Warrant 143 75 1 100 80 2 or more 100 80 70% Factor a 143 75 1 75 60 a For communities less than 10,000 population or above 40 mph (64 km/h) on major street. Only applies to Warrants 2 and 3. b The minimum minor road volume occurs when the major street volume is approximately 1,450 veh/h or at 1,050 veh/h when the community is less than 10,000 or the speed on the major road exceeds 40 mph (64 km/h). c Warrant 4 requires 190 ped/h crossing the major road in the peak hour. To compare with Warrant 3, this value was adjusted to a highest approach value by assuming a 75/25 directional distribution split. d The minimum minor road volume occurs when the major street volume is approximately 1,050 veh/h or more or at 750 veh/h when the community is less than 10,000 or the speed on the major road exceeds 40 mph (64 km/h). e Warrant 4 requires 100 ped/h crossing the major road during 4 h. To compare with Warrant 2, this value was adjusted to a highest approach value by assuming a 75/25 directional distribution split.
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24 number of individuals willing to walk such a distance was handled in the signal warranting criteria (55). The recom- influenced by the number of lanes at the site (six lanes), mendations include counting pedestrians on the minor speed and volume of traffic (high), and existing treatment approaches as vehicles and bicycles are counted now, which (marked crosswalk only). Several of the respondents would change the vehicular-based warrants to all-mode, selected "yes" to the question and then commented that intersection-based warrants and would allow the pedes- they walk to the nearby crossing "most of the time" or trian warrant to focus on just the midblock crossing, which "sometimes" depending on the weather or other factors. would make the warrant more straightforward. The largest · Reduction Criteria Based on Walking Speeds. In the current issue to be considered is how to count pedestrians versus warrant, the only reduction factor is based on walking speed, vehicles. The pedestrians are exposed to inclement weather and it only affects the pedestrian volume criterion. This reduc- conditions, have slower acceleration and speed rates result- tion factor was introduced in order to accommodate older ing in longer crossing times, and are at considerably more pedestrians and persons with disabilities. Specifically, if the risk than occupants of vehicles, especially as the major average walking speed is less than 4 ft/s (1.2 m/s), then a street speeds increase. Therefore, developing an equiva- reduction of the pedestrian volume of up to 50 percent can be lency factor for pedestrians at intersections seems reason- implemented. Chapter 6 and Appendix M include recom- able. Critical gaps for vehicles and pedestrians are provided mendations on walking speeds based on the research con- in the Highway Capacity Manual and the AASHTO Green ducted as part of this TCRP/NCHRP study. Book (23, 56). Table 11 lists the critical gaps to cross a sam- ple roadway. A pedestrian requires more time to cross an intersection than does a vehicle. To cross a two-lane road- Potential Factors way, a pedestrian needs 39 percent more time (factor of Potential factors include the following: 1.4) than does a vehicle. At a four-lane street, a pedestrian needs twice as much time (or a factor of 2.0) than does a · Pedestrian Generators (Transit Stops). The closeness of a vehicle. Canada's pedestrian signal procedure includes pedestrian generator is not considered within the current equivalent adult units with children and those with dis- pedestrian signal warrant. abilities counting as 2.0 adults and seniors counting as 1.5 · School Warrant. The school signal warrant has a unique adults. The concept of counting all road users on the minor feature that may lend itself to the handling of all pedestrian street approach is not novel to the MUTCD. The current crossing treatments. In the school warrant, the main con- MUTCD multi-way Stop warrant has a criterion that sideration is the ratio of the number of adequate gaps to includes the summation of vehicles, bicycles, and pedestri- the number of minutes the crossing is being used. This ans on the minor street approach. ratio could be used to set thresholds for various crossing · Vehicle Speed. Most of the current vehicular-based traffic treatments. signal warrants include a reduction factor based on the · Crash Experience. As indicated in Appendix G, other speed of the vehicles on the major street. The pedestrian countries use crash experience to justify the installation of signal warrant also included the same reduction factor a traffic signal. The MUTCD includes a crash experience until the 1988 revision. warrant, but it is focused on vehicular crashes. Including a · Pedestrian Delay. The HCM includes a procedure to esti- factor in the warranting criteria that considers safety in mate pedestrian delay for an unsignalized intersection. The terms of pedestrian-related crashes, especially because of average delay of pedestrians at an unsignalized intersection the vulnerability associated with pedestrian crashes, may crossing depends on the critical gap, the vehicular flow rate be reasonable. of the subject crossing, and the mean vehicle headway. The · Counting Pedestrians on the Minor Approach with HCM Exhibit 18-13 (reproduced as Table 12) is then used to Vehicular and Bicycle Volumes. Other research has rec- determine the LOS of the crossing. A signal warrant could be ommended more global changes to the way pedestrians are developed based on a function of the pedestrian delay. Table 11. Critical gaps for vehicles and pedestrians at an unsignalized intersection. Critical Gaps Through Lanes Vehicle (s) Pedestrians (s) 2 6.5 9.0 4 7.5 15.0 HCM Equation 18-17, Green Book Exhibit 9-57, assume 12-ft (4-m) lanes, 4 Source assume passenger car ft/s (1.2 m/s) walking speed, and 3-s start up