crosswalk research

12
Field Studies of Pedestrian Walking Speed and Start-Up Time RICHARD L. KNOBLAUCH, MARTIN T. PIETRUCHA, AND MARSHA NITZBURG Today’s traffic environment is not well adapted to the needs of the older pedestrian. Unfortunately, except in the case of children, little is known about the characteristics and behavior of pedestrians. Although the simple fact that older pedestrians walk more slowly than younger ones is easily supported by field data, existing data on walking speeds and start-up time (i.e., the time from the onset of a Walk signal until the pedestrian steps off the curb) have many shortcomings. A series of field studies was conducted to quantify the walking speed and start-up time of pedestrians of various ages under different conditions. Sixteen crosswalks in four urban areas were studied. Data were collected on walking speeds and start-up times relative to site and environmental factors, including street width, posted speed, curb height, grade, num- ber of vehicle travel lanes, signal cycle length, pedestrian-signal type, street functional classification, crosswalk type, and channelization. Data on a subject group of pedestrians who appeared to be 65 years of age or older and a control group of pedestrians under age 65 were col- lected. Results indicate a broad range of walking speeds among pedes- trians. The 15th-percentile walking speed for younger pedestrians (ages 14 to 64) was 1.25 m/sec (4.09 ft/sec); for older pedestrians (ages 65 and over) it was 0.97 m/sec (3.19 ft/sec). For design purposes values of 1.22 m/sec (4 ft/sec) for younger pedestrians and 0.91 m/sec (3 ft/sec) for older pedestrians are appropriate. Results also indicated that walk- ing rates are influenced by a variety of factors, including the functional classification and vehicle volumes on the street being crossed, the street width, weather conditions, the number of pedestrians crossing in a group, the signal cycle length, the timing of the various pedestrian-signal phases, whether right turn on red is allowed, pedestrian signals, medi- ans, curb cuts, crosswalk markings, stop lines, and on-street parking. However, for each of these factors, the effect on crossing speeds, although statistically significant, is not meaningful for design. The older road user has received much attention during the past decade, and with good reason. The proportion of those over age 65 in the North American population is increasing and will continue to increase dramatically. Research related to older road users has also increased. In 1992 the Federal Highway Administration was spon- soring eight major research projects on older road users. An exam- ination of these projects indicates that older drivers, not older pedes- trians, receive the majority of attention in research related to older road users. Today’s traffic environment is not well adapted to the needs of the older pedestrian. Unfortunately, except in the case of children, very little is known about the characteristics and behavior of pedes- trians. The simple fact that older pedestrians walk more slowly than younger ones is easily supported by field data; however, the exist- ing data on walking speeds and start-up time (i.e., the time from the TRANSPORTATION RESEARCH RECORD 1538 27 onset of a Walk signal until the pedestrian steps off the curb) have many shortcomings. For example, Dahlstedt (1) instructed a group of people aged 70 or older to cross an intersection at fast, very fast, or normal speed. Fast for about 60 percent of the group was less than 1.22 m/sec (4 ft/sec); normal for 90 percent of the group was also less than 1.22 m/sec (4 ft/sec), and the 85th-percentile speed was about 0.67 m/sec (2.2 ft/sec). The Manual on Uniform Traffic Control Devices (MUTCD) (2) suggests a walking speed of 1.22 m/sec (4 ft/sec) for traffic signal timing. A literature review by McGee, et al. ( 3) indi- cated that many pedestrians—perhaps 30 percent of the population, many of whom are older—do not normally walk that quickly. In fact, the Traffic Control Devices Handbook (TCDH) (4) also notes that one-third of all pedestrians cross more slowly, with 15 percent at or below 1.06 m/sec (3.5 ft/sec). TCDH states that “those having slower walking speeds have the moral and legal right to complete the crossing once they have entered the intersection.” The Traffic Engineering Handbook (5) suggests that 0.91 to 0.99 m/sec (3 to 3.25 ft/sec) would be a more appropriate value to use for traffic signal timing. An Institute of Transportation Engineers committee concerned with pedestrian issues (6) conducted a survey at a Florida location with a large population of elderly pedestrians. The committee recommended 0.76 m/sec (2.5 ft/sec) as an appro- priate walk speed (for locations with a high volume of elderly pedestrians), and found this speed to be adequate for 87 percent of pedestrians observed. However, walking speeds are influenced by environmental, traffic, and pedestrian characteristics. The effects of terrain on walking speeds are unknown, although it can be expected that the elderly would be affected more when walking up or down a grade than the young. Similarly, it can be expected that the elderly would react more strongly to higher vehicular densi- ties and traffic speeds, out of a fear of traffic. Moore ( 7 ) noted that the closer the approaching vehicle, the faster the mean crossing time—1.52 m/sec (5 ft/sec) when the approaching vehicle was 3 sec away, 1.22 m/sec (4 ft/sec) when the approach- ing vehicle was not too close. Finally, pedestrian speed on sidewalks and crosswalks is strongly related to the number of pedestrians in the flow. The relationship between speed, flow, and space occupied (i.e., density) for a representative popula- tion group has been examined by Fruin ( 8) and others. How- ever, the abilities of the elderly in crowds have not yet been documented. Because of the shortcomings in data on the walking speeds of older pedestrians a series of field studies was conducted to quantify the walking speed and start-up time of pedestrians of various ages under different environmental conditions. R.L. Knoblauch and M. Nitzburg, Center for Applied Research, 9308 Georgetown Pike, Great Falls, Va. 22066. M.T. Pietrucha, The Pennsylva- nia State University, The Pennsylvania Transportation Institute, Research Office Building, University Park, Pa. 16802.

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Crosswalk Research

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Page 1: Crosswalk Research

Field Studies of Pedestrian Walking Speed and Start-Up Time

RICHARD L. KNOBLAUCH, MARTIN T. PIETRUCHA, AND MARSHA NITZBURG

Today’s traffic environment is not well adapted to the needs of theolder pedestrian. Unfortunately, except in the case of children, little isknown about the characteristics and behavior of pedestrians. Althoughthe simple fact that older pedestrians walk more slowly than youngerones is easily supported by field data, existing data on walking speedsand start-up time (i.e., the time from the onset of a Walk signal until thepedestrian steps off the curb) have many shortcomings. A series of fieldstudies was conducted to quantify the walking speed and start-up timeof pedestrians of various ages under different conditions. Sixteencrosswalks in four urban areas were studied. Data were collected onwalking speeds and start-up times relative to site and environmentalfactors, including street width, posted speed, curb height, grade, num-ber of vehicle travel lanes, signal cycle length, pedestrian-signal type,street functional classification, crosswalk type, and channelization.Data on a subject group of pedestrians who appeared to be 65 years ofage or older and a control group of pedestrians under age 65 were col-lected. Results indicate a broad range of walking speeds among pedes-trians. The 15th-percentile walking speed for younger pedestrians (ages14 to 64) was 1.25 m/sec (4.09 ft/sec); for older pedestrians (ages 65and over) it was 0.97 m/sec (3.19 ft/sec). For design purposes values of1.22 m/sec (4 ft/sec) for younger pedestrians and 0.91 m/sec (3 ft/sec)for older pedestrians are appropriate. Results also indicated that walk-ing rates are influenced by a variety of factors, including the functionalclassification and vehicle volumes on the street being crossed, the streetwidth, weather conditions, the number of pedestrians crossing in a group,the signal cycle length, the timing of the various pedestrian-signalphases, whether right turn on red is allowed, pedestrian signals, medi-ans, curb cuts, crosswalk markings, stop lines, and on-street parking.However, for each of these factors, the effect on crossing speeds,although statistically significant, is not meaningful for design.

The older road user has received much attention during the pastdecade, and with good reason. The proportion of those over age 65in the North American population is increasing and will continue toincrease dramatically. Research related to older road users has alsoincreased. In 1992 the Federal Highway Administration was spon-soring eight major research projects on older road users. An exam-ination of these projects indicates that older drivers, not older pedes-trians, receive the majority of attention in research related to olderroad users.

Today’s traffic environment is not well adapted to the needs ofthe older pedestrian. Unfortunately, except in the case of children,very little is known about the characteristics and behavior of pedes-trians. The simple fact that older pedestrians walk more slowly thanyounger ones is easily supported by field data; however, the exist-ing data on walking speeds and start-up time (i.e., the time from the

TRANSPORTATION RESEARCH RECORD 1538 27

onset of a Walk signal until the pedestrian steps off the curb) havemany shortcomings.

For example, Dahlstedt (1) instructed a group of people aged 70or older to cross an intersection at fast, very fast, or normal speed.Fast for about 60 percent of the group was less than 1.22 m/sec (4 ft/sec); normal for 90 percent of the group was also less than 1.22 m/sec (4 ft/sec), and the 85th-percentile speed was about 0.67 m/sec (2.2 ft/sec).

The Manual on Uniform Traffic Control Devices (MUTCD) (2) suggests a walking speed of 1.22 m/sec (4 ft/sec) for trafficsignal timing. A literature review by McGee, et al. (3) indi-cated that many pedestrians—perhaps 30 percent of thepopulation, many of whom are older—do not normally walk that quickly. In fact, the Traffic Control Devices Handbook(TCDH) (4) also notes that one-third of all pedestrians crossmore slowly, with 15 percent at or below 1.06 m/sec (3.5 ft/sec).

TCDH states that “those having slower walking speeds have the moral and legal right to complete the crossing once they have entered the intersection.”

The Traffic Engineering Handbook (5) suggests that 0.91 to 0.99m/sec (3 to 3.25 ft/sec) would be a more appropriate value to usefor traffic signal timing. An Institute of Transportation Engineerscommittee concerned with pedestrian issues (6) conducted a surveyat a Florida location with a large population of elderly pedestrians.The committee recommended 0.76 m/sec (2.5 ft/sec) as an appro-priate walk speed (for locations with a high volume of elderlypedestrians), and found this speed to be adequate for 87 percent ofpedestrians observed.

However, walking speeds are influenced by environmental,traffic, and pedestrian characteristics. The effects of terrain on walking speeds are unknown, although it can be expected that the elderly would be affected more when walking up or down a grade than the young. Similarly, it can be expected that the elderly would react more strongly to higher vehicular densi-ties and traffic speeds, out of a fear of traffic. Moore (7) noted that the closer the approaching vehicle, the faster the meancrossing time—1.52 m/sec (5 ft/sec) when the approaching vehicle was 3 sec away, 1.22 m/sec (4 ft/sec) when the approach-ing vehicle was not too close. Finally, pedestrian speed onsidewalks and crosswalks is strongly related to the number ofpedestrians in the flow. The relationship between speed, flow, and space occupied (i.e., density) for a representative popula-tion group has been examined by Fruin (8) and others. How-ever, the abilities of the elderly in crowds have not yet been documented.

Because of the shortcomings in data on the walking speeds ofolder pedestrians a series of field studies was conducted to quantifythe walking speed and start-up time of pedestrians of various agesunder different environmental conditions.

R.L. Knoblauch and M. Nitzburg, Center for Applied Research, 9308Georgetown Pike, Great Falls, Va. 22066. M.T. Pietrucha, The Pennsylva-nia State University, The Pennsylvania Transportation Institute, ResearchOffice Building, University Park, Pa. 16802.

Page 2: Crosswalk Research

METHOD

Site Selection

Sixteen crosswalks at signal-controlled intersections in four urbanareas (Richmond, Virginia; Washington, D.C.; Baltimore, Mary-land; and Buffalo, New York) were selected. Sites were selected toallow for a minimum of 26 to 30 pedestrians over 65 years of ageto be observed during an 8-hr data-collection period. During pilottesting, estimates of population variance were computed and a sam-ple size of 26 to 30 was determined to be sufficient to quantify theeffects of site-specific factors. To quantify walking speeds andstart-up times relative to different site and environmental factors,the following types of site-specific information were recorded:

• Street width,• Posted speed,• Curb height,• Grade,• Number of travel lanes,• Signal cycle length,• Pedestrian signal type,• Street classification,• Crosswalk type, and• Channelization.

Weather Conditions

Data were collected during three different types of weatherconditions:

• Dry: clear (no precipitation), with dry roads and dry sidewalk;• Rain: any type of rain from drizzle and mist to moderate rain,

with wet roads and wet curbs. Data were not collected during heavyrain because pedestrians tended not to be outside. Data were alsocollected immediately after the precipitation stopped when the roadand sidewalk were still wet; and

• Snow: when there was snow or ice in the atmosphere, on theroad or sidewalk, or both.

Data were collected on weekdays during daylight conditions.Surface conditions at the curb, in the crosswalk, weather condi-tions, and the estimated wind intensity were recorded for eachobservation.

Subject Selection

Data were collected on a subject group of pedestrians who appearedto be 65 years of age or older. Data on a control group of pedestri-ans under age 65 were also collected. The following individualswere specifically not observed:

• Children under 13 years of age;• Pedestrians carrying children, heavy bags, or suitcases;• Pedestrians pushing strollers or grocery carts;• Pedestrians holding hands or assisting others across the road-

way;• Pedestrians using a quadpod cane, walker, two canes, or

crutches;

28 TRANSPORTATION RESEARCH RECORD 1538

• People in wheelchairs; and• Pedestrians walking bikes or dogs.

To accurately quantify normal walking speeds of the varioussubject groups, pedestrians who exhibited any of the followingbehaviors were also not observed:

• Crossing diagonally,• Stopping or resting at the median,• Entering the roadway running (anything faster than a fast

walk),• Stepping into the roadway (leaving the curb) before starting to

cross or waiting for traffic during crossing, and• Entering or exiting the roadway more than 1.2 m (4 ft) outside

the crosswalk.

The gender of each subject was recorded, as well as whether heor she was walking alone or in a group. The group size was alsonoted when applicable. A group was defined as two or more pedes-trians crossing the roadway at about the same time, regardless ofwhether or not they were apparently friends or associates.

In addition, subjects’ paths were monitored to determine whetherthey started and ended their crossings inside or outside the cross-walk. Inside the crosswalk was established as within or on thepainted crosswalk lines.

Compliance with the pedestrian signal (or traffic signal for siteswithout pedestrian signals) was recorded. Observers specificallyrecorded whether the Walk, Don’t Walk, or flashing Don’t Walksignal was on at the start of the subject’s crossing. When the signalchanged during the crossing the information was recorded alongwith the subject’s location—whether the first or second half of thecrossing—at the time the change occurred. Nine other pedestrianbehaviors were recorded when they occurred:

• Confusion (hesitation, change in direction of travel) exhibitedbefore crossing;

• Confusion exhibited after entering the roadway;• Cane use;• Following the lead of other pedestrians;• Inattention when pedestrian signal changed to Walk;• Stopping in the crosswalk during the crossing;• Difficulty going down the curb;• Difficulty going up the curb; and• Running during part of the crossing (anything faster than a fast

walk).

To verify the accuracy and reliability of the age-estimationabilities of the observers, several field verifications were done. First,the age-estimation accuracy of several observers was measured,then correlations between the estimates of all of the observers weredetermined. The results of these verification procedures arediscussed after the next section.

Procedure

Pedestrian crossing times were measured with a hand-held, digital,electronic stopwatch. The watch was started as the subject steppedoff the curb and stopped when the subject stepped up on the oppo-site curb after crossing. At sites with a pedestrian signal, pedestrianstart-up times were also measured.

Page 3: Crosswalk Research

Verification of Observer Age Estimates and Start-up Time Measurement

To determine the ability of the field observers to properly identifyolder pedestrians a simple verification procedure was conducted.Five field observers estimated the ages of a randomly selected sam-ple of nine pedestrians who ranged in age from 54 to 85 years. Withone exception, a 62-year-old male, each observer correctly identi-fied as over 65 each pedestrian who subsequently reported his or herage as over 65. All five observers thought that the 62-year-old malewas over 65; estimates ranged from 68 to 75 years old.

Interrater reliability for age was assessed using intraclass corre-lations and Pearson r correlations. The intraclass correlation was .78for the five raters. Pearson r correlations between individual ratersranged from .71 to .93; between subjects’ actual age and each raterit ranged from .70 to .82. This indicates that the observers, as agroup, were quite good at identifying pedestrians over the age of 65and that there was a more than acceptable level of agreement amongobservers.

A similar procedure was used to verify the reliability of the stop-watch measurements of pedestrian crossing times. The crossingtimes of the same nine pedestrians were measured by the five fieldobservers. Again, intraclass correlations and Pearson r correlationswere used to determine interrater reliabilities. The intraclass corre-lation was .998 for the five raters, and all Pearson r correlationsbetween individual raters were greater than .99. This indicates thatthe observers were each following the timing procedure in a similarmanner.

RESULTS

The overall objectives of the research dictated the orientation of dataanalysis, the purpose of which was to gather descriptive informationon the walking abilities and street-crossing behavior of older pedes-trians. Therefore, the data analysis is descriptive, as opposed toanalytical. The walking speeds and start-up times of young and olderpedestrians across a variety of situational factors are described.Although many of the differences shown are statistically significant,it is important to consider the absolute magnitude or meaningfulnessof these differences.

Pedestrian Walking Speeds

Table 1 presents the mean and 15th-percentile walking speeds inmeters per second for young and older pedestrians at different typesof locations and under several different environmental conditions.The 15th-percentile walking speed represents the speed that 15 per-cent of the pedestrians do not exceed; conversely, it is the speed that85 percent of the pedestrians do exceed. A total of 7,123 pedestri-ans were observed. Included were 3,458 pedestrians under 65 yearsof age and 3,665 pedestrians 65 and over. These data describe all thepedestrians observed: those crossing in compliance with the signaland those crossing against the signal. As is subsequently described,those who cross against the signal tend to walk more quickly.

The table shows that each of the site and environmental factorscollected indicate a significant effect caused by age and by each ofthe site and environmental characteristics. For approximately one-half of the site factors examined there was also a significant inter-action between pedestrian age and the site factor. This is indicated

Knoblauch et al. 29

by notation of an age-by-site interaction (A 3 S) in the significancecolumn. Although many of the mean differences shown are statis-tically significant, this is in part because of the relatively largenumber of observations made. When examining these tables it isimportant to consider the relative magnitude of the differences andwhether or not the differences are meaningful. Many were found tobe statistically significant, but do not make any practical differenceto facilities design practices. The following discussion highlightssome of the walking-speed differences noted for the entire sampleof pedestrians observed.

The mean walking speed for younger pedestrians was 1.51 m/sec(4.95 ft/sec); it was 1.25 m/sec (4.11 ft/sec) for older pedestrians.The 15th-percentile speeds were 1.25 and 0.97 m/sec (4.09 and 3.19ft/sec) for younger and older pedestrians, respectively. These meandifferences are significant at the 0.05 level. Other highlights includethe following observations.

• Young male pedestrians had the fastest walking speeds [1.56m/sec (5.11 ft/sec)]; older females had the slowest [1.19 m/sec (3.89ft/sec)]. The differences between younger men and younger women[0.10 m/sec (0.32 ft/sec)] and between older men and older women[0.13 m/sec (0.42 ft/sec)] are approximately the same;

• Pedestrians who start on the Walk signal walk more slowlythan those who cross on either the flashing Don’t Walk or the steadyDon’t Walk. The differences between the Walk crossers and theflashing Don’t Walk crossers suggest that some pedestrians mayunderstand the concept of the clearance phase, specifically, thatalthough it is dangerous to cross on the steady Don’t Walk (and ifdoing so one should walk as fast as possible), it is slightly less dan-gerous to cross on the flashing Don’t Walk. [This is contrary toinformation from some other studies (e.g., Zegeer [9]), which indi-cate a general lack of understanding of the flashing Don’t Walk.] Atsites without pedestrian signals pedestrians who start to cross legally(on the green) also tend to walk more slowly than those crossingagainst the signal indication (on the red). These differences betweencompliers and noncompliers have important implications to thedesign process. It is believed that the walking speeds of compliersprovide a more appropriate basis for design than do the walkingspeeds of those who are crossing illegally;

• Locations with longer signal cycles had faster crossing speeds,probably because such locations tend to be wider roadways;

• Shorter pedestrian-signal times (Walk and flashing Don’tWalk) also tend to be associated with faster walking speeds. It is notknown if this relationship is causally related (i.e., the pedestrianswalk faster because they know the crossing times are short) or if theshorter crossing times are typically displayed where pedestrianstend to walk more quickly (i.e., local streets). As might be expected,the walking speeds associated with the various steady Don’t Walkcycle lengths are similar to those associated with the overall cyclelength.

Table 2 presents the mean and 15th-percentile of walking speedsfor younger and older pedestrians who were observed crossing withthe signal, that is, compliers. This subset included 4,460 pedestri-ans, approximately 62 percent of those included in Table 1. As agroup, they tend to walk more slowly than the pedestrians who crossillegally. The mean crossing speed for the younger compliers was1.46 m/sec (4.79 ft/sec) versus 1.51 m/sec (4.95 ft/sec) for allyounger pedestrians observed. The older compliers averaged 1.20m/sec (3.94 ft/sec), whereas all the older pedestrians observed aver-aged 1.25 m/sec (4.11 ft/sec). Both of these differences are signifi-

Page 4: Crosswalk Research

TABLE 1 Mean and 15th-Percentile Walking Speeds in Meters per Second for Young and OlderPedestrians: All Pedestrians

(continued on next page)

Page 5: Crosswalk Research

(continued on next page)

TABLE 1 (continued)

Page 6: Crosswalk Research

cant at the 0.05 level (t-test). The 15th-percentile crossing speed forthe younger compliers was 1.21 m/sec (3.97 ft/sec), whereas oldercompliers crossed at 0.94 m/sec (3.08 ft/sec). This difference wascompared using the test statistic:

This produced a Z-ratio of 23.26, indicating that the 15th per-centile values are significantly different below the 0.001 level.

Highlights of the effect of site-related and environmental factorson the walking speeds of the compliers are as follows:

• Younger females walk 0.1 m/sec (0.32 ft/sec) more slowly thanyounger males, whereas older females are 0.12 m/sec (0.4 ft/sec)slower than older males;

• Those who start or end their crossing outside the crosswalktend to walk more quickly;

• Compliers crossing at locations with pedestrian signals are notwalking more quickly than compliers crossing at locations with onlya traffic signal;

• Single compliers also tend to walk more quickly than compli-ers walking in a group;

• Weather conditions have a significant effect on walking speed.Older pedestrians, especially, walk more slowly when it is snowing.One of the slowest 15th-percentile values observed [0.9 m/sec (2.94ft/sec)] was for older pedestrians crossing snow-covered roadways;

• Longer signal cycle lengths appear to be associated with fasterwalking times;

• Compliers also tend to walk more quickly at locations withshort steady Walk and short flashing Walk intervals; and

• Longer steady Don’t Walk intervals, like longer total signalcycle length, appear to be associated with slower walking times.

Discussion of Pedestrian Walking Speed Results

Not surprisingly, the data set for all pedestrians observed containswalking speeds that are significantly faster than the data set for onlythose who crossed with the signal (compliers). For design purposesit is appropriate to use the data based on compliers. The walkingspeeds for this subset show statistically significant variations acrossa variety of site and environmental conditions. However, both themean and 15th-percentile data are tightly clustered for both youngerand older pedestrians. The 15th-percentile value represents thewalking speed that is exceeded by all but the slowest-walking 15percent of the older pedestrian population. The means for theyounger pedestrians range from 1.38 to 1.56 m/sec (4.51 to 5.12

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32 TRANSPORTATION RESEARCH RECORD 1538

ft/sec) across all conditions, with an overall mean speed of 1.46m/sec (4.79 ft/sec). The means for the older pedestrians range from1.14 m/sec to 1.29 m/sec (3.73 ft/sec to 4.24 ft/sec), with an overallmean speed of 1.21 m/sec (3.98 ft/sec). For design purposes a meanspeed of 1.22 m/sec (4.00 ft/sec) would appear appropriate.

The 15th-percentile scores are also tightly clustered. For youngerpedestrians they range from 1.18 to 1.27 m/sec (3.86 to 4.18 ft/sec)with an average 15th-percentile speed across all sites of 1.19 (3.97).For older pedestrians, they range from 0.88 to 1.01 m/sec (2.90 to3.31 ft/sec), with an average 15th-percentile speed across all sites of 0.94 m/sec (3.08 ft/sec). For design purposes for which a 15th-percentile value is appropriate it would appear that 0.91 m/sec (3 ft/sec) would be reasonable to use for older pedestrians.

Pedestrian Start-up Times

Table 3 presents the mean and 15th-percentile start-up times foryoung and older pedestrians. Because start-up times could be mea-sured for only those pedestrians who waited for the signal to changebefore starting their crossing, these pedestrians are by definitioncompliers. Start-up times were measured only at locations with apedestrian signal and were defined, as has been stated as the elapsedtime from the onset of a Walk signal to the moment when a pedes-trian steps off the curb and starts to cross. Start-up times were mea-sured only for those pedestrians who stopped at the curb and waitedfor the signal to change before starting to cross.

It is interesting that the same site and environmental factors thatalmost always showed significant interactions with walking speeds(as shown in Tables 1 and 2) did not (with the exception of roadwaywidth) have a significant interaction with start-up time. However,with the single exception of day of week, the start-up times viewedagainst every factor were significantly longer for older pedestriansthan for younger pedestrians.

It could be hypothesized that being in a group would affect start-up time. The presence of others could conceivably delay start-up or,alternatively, it might be expected that the group would start cross-ing as soon as the quickest pedestrian in the group started.

The data indicate that there is no such effect. Younger pedestrianshad identical mean start-up times (1.93 sec) whether alone or in agroup. Older pedestrians had nearly identical start-up times of 2.5sec when alone and 2.43 sec in a group.

Some of the site and environmental factors included in Tables 1and 2 are not included in Table 3. This is because the distribution ofthe sample across some of the categories did not occur with suffi-cient frequency to allow meaningful comparisons. For example, allbut 11 of the 355 younger-pedestrian observations occurred onmajor arterials, so there were insufficient cases on either collector-

TABLE 1 (continued)

Page 7: Crosswalk Research

TABLE 2 Mean and 15th-Percentile Walking Speeds in Meters per Second for Young and OlderPedestrians: All Compliers

(continued on next page)

Page 8: Crosswalk Research

TABLE 2 (continued)

(continued on next page)

Page 9: Crosswalk Research

distributor or local streets to conduct meaningful analyses. This wasbecause pedestrians rarely wait for the pedestrian signal unless theyare forced to do so by oncoming traffic.

Discussion of Pedestrian Start-Up Time Results

Start-up times for the pedestrians observed did not show the samevariability across site and environmental conditions that was notedfor the walking-speed data. This was largely because of the limitedvariability between the sites at which start-up time could be mea-sured. Start-up time could be measured only when the pedestrianschose to wait for the proper signal indication before starting to cross,which typically happens only when pedestrians are forced to waitbecause of oncoming traffic.

The mean start-up times for younger pedestrians varied from 1.83sec for males to 2.01 sec for females, with an overall mean value of1.93 sec. For older pedestrians the mean values ranged from 2.39sec for males to 2.57 sec for females, with an overall mean value of2.48 sec. For design purposes a mean value of 2.5 sec would appearsto be appropriate for older pedestrians, and a mean value of 2.0 secwould be suitable for younger pedestrians.

The 85th-percentile values for younger pedestrians ranged from2.76 sec (males) to 3.31 sec (females), with an overall value of 3.06sec. For older pedestrians start-up times varied from 3.66 to 3.95sec, with an overall value of 3.76 sec. For design purposes an 85th-percentile value of 3.75 sec would be appropriate for older pedes-trians, and an 85th-percentile value of 3 sec would be suitable foryounger pedestrians.

SUMMARY

Based on the abundance of literature on the subject it would appearthat pedestrian walking speeds have been studied by many differentresearchers in great detail. However, examination of some of thesestudies reveals many differing results for older-pedestrian walkingspeeds. There is also little or no information on the ranges or distri-butions of these older-pedestrian walking speeds. Furthermore,when specific studies are examined in detail, looking specifically atnumber of observations, age of subjects observed, and range ofconditions observed, it is clear that before the described effort adefinitive walking speed study (especially for older pedestrians) hadyet to be done.

Information on pedestrian start-up time is extremely important inmany aspects of highway design. As far as can be determined, thereis no existing information on this subject. Therefore, the resultspresented give a firm basis for the selection of reliable pedestrianwalking speeds and pedestrian start-up times.

Knoblauch et al. 35

The walking speed and start-up time data sets include informationon both compliers and noncompliers. Compliers are pedestrianswho cross during an appropriate pedestrian signal or traffic signalindication, and noncompliers are pedestrians who violate the pedes-trian signal or traffic-signal indication. Pedestrians who violatesignal indications likely do so knowingly. Therefore, they are awareof the increased (relative) risk in which they may be placing them-selves and because of this they choose to leave the sidewalk area orwalk at a speed that is different from the speed they might choose ifthey were crossing with the signal. For this reason the only infor-mation appropriate for design purposes are the data on pedestriancompliers, which are shown in (Table 2).

In most cases a designer’s interest in pedestrian start-up times andwalking speeds is twofold. First, a designer wants to have a true rep-resentation of how much time is needed by pedestrians of all agesand abilities to cross specific sections of roadway so a geometric lay-out and operational situation that is safe can be designed. Second, a designer is usually interested in having a design operate asefficiently as possible. This frequently translates into a desire tominimize the time necessary to accommodate the pedestrian andmaximize the time available for the movement of vehicle traffic.With better information on start-up times and walking speeds rela-tive to the site and environmental factors discussed, a designer canconsider the effect of many different elements relative to these twomajor design objectives.

The data indicate statistically significant differences betweenstart-up times and walking speeds by age category for most of the site and environmental factors discussed. It is also noted that the intuitive directionality of the start-up times and walking speeds(i.e., the times and speeds change in the direction expected, given anintuitively based supposition of the influence of the factor) followgeneral expectations. However, in every case the differencesbetween times and speeds, although statistically significant, are notmeaningful for a designer.

Given the practically insignificant changes between start-up timesand walking speeds by age category for most of the site and envi-ronmental factors, it is recommended that designers focus on theaggregated times and speeds for all complying walkers.

Past studies have shown that there are no defendable criteria for acceptable minimum levels of human performance. Manyresearchers have suggested that performance be arbitrarily set at the15th-85th percentile, nominally the break points in the cumulativefrequency (ogive) plot of normally distributed data. It is believedthat by using these values the bulk of the subject population isaccommodated and only the true outliers are excluded from consid-eration. Therefore, it is recommended that the 15th-percentile val-ues for older pedestrians for both start-up times and walking times(shown in Tables 2 and 3) be adopted as the standard for each ofthese parameters.

TABLE 2 (continued)

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TABLE 3 Mean and 85th-Percentile Start-Up Times in Seconds for Young and Older Pedestrians: All Pedestrians

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TABLE 3 (continued)

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ACKNOWLEDGMENT

The research reported in this paper was sponsored by FHWA, U.S.Department of Transportation.

REFERENCES

1. Dahlstedt, S. Walking Speeds and Walking Habits of Elderly People.Swedish Road and Transport Research Institute, Stockholm, undated.

2. Manual on Uniform Traffic Control Devices for Streets and Highways.FHWA, U.S. Department of Transportation, 1988.

3. McGee, H. W., K. G. Hooper, W. E. Hughes, and W. Benson. HighwayDesign and Operational Standards Affected by Driver Characteristics:Final Technical Report. Report FHWA/RD 83/015. FHWA, U.S. Depart-ment of Transportation, 1983.

4. Traffic Control Devices Handbook. FHWA, U.S. Department of Trans-portation, 1983.

38 TRANSPORTATION RESEARCH RECORD 1538

5. Dewar, R. E. Driver and Pedestrian Characteristics. In Traffic Engineer-ing Handbook (4th edition, J. Pline, ed.), Prentice Hall, Englewood Cliffs,N.J., 1992.

6. ITE Committee 4A-6, Pedestrians. Traffic Control Devices for Elderlyand Handicapped Pedestrians. Institute of Transportation Engineers,Washington, D.C., undated.

7. Moore, R. L. Psychological Factors of Importance in Traffic Engineer-ing. Presented at International Study Week in Traffic Engineering, Stresa,Italy, 1956.

8. Fruin, J. J. Pedestrian Planning and Design. Elevator World, 1987.9. Zegeer, C. V. Synthesis of Safety Research—Pedestrians. FHWA, U.S.

Department of Transportation, 1991.

The contents of this paper reflect the views of the authors and do not neces-sarily reflect the official views or policies of the U.S. Department of Trans-portation.

Publication of this paper sponsored by Committee on Pedestrians.

TABLE 3 (continued)