Part 2. Crashes Involving Pedestrians

Introduction

The sheer number of pedestrians killed or seriously injured in U.S. traffic collisions each year is an important consideration in the Nation's highway transportation system. The NHTSA estimated that 5,300 pedestrians were killed in the United States during 1997 (Traffic Safety Facts, 1997). NHTSA also reported 77,000 nonfatal injuries. Casualties of this magnitude take on even greater meaning in view of the national policy to encourage increased walking as a matter of both transportation and health.

Limitations of National Pedestrian Crash Data

Pedestrian crash statistics must be considered with two caveats: First, the numbers presented in this report are estimates, aggregated from information compiled in 50 States plus the District of Columbia, or taken from studies that sample pedestrian collisions. Predictably, there is some uncertainty in the reporting processes and expectable variations due to sampling differences. Second, definitions vary among agencies. Thus, fatality estimates from the National Safety Council (NSC) differ somewhat from those of the NHTSA due to their definitions of death. NSC counts a traffic fatality as any crash death that ensues within 1 year after the crash, whereas NHTSA only counts those deaths that occur within 30 days. Other totals would result if, for example, traffic death counts were confined to victims who died at the crash scene.

Another caution pertains to interpreting the following data tables, which may themselves be overly simplistic. A collision may be associated with several factors, therefore a table that displays only two or three factors leaves much unsaid. For example, a table depicting pedestrian crashes by time of occurrence will show that a certain proportion occurs at night. However, not all of the observed trends shown in such a table would be caused by reduced nighttime visibility. Although reduced visibility at night plays an important role in the likelihood of a crash, the nighttime figures are also influenced by the number of people who are exposed to risk at night as opposed to in the daytime, the ages of the pedestrians, and the role of alcohol. Thus,any table of crash data reflects the influence of variables not shown, as well as the influence of the variables that are depicted.

Moreover, many studies do not consider the number of people actually exposed to risk.

Reports reviewed here span the period during which standardized terminology was evolving. Thus, various authors use the term "accident", "collision", or "crash" to describe the phenomena under examination here. While the terms are sometimes used interchangeably, "crash" has become the term preferred by safety organizations.

The Number of Pedestrian Fatalities

The NSC annually publishes an estimate of U.S. pedestrian deaths for the most recent year available, as well as for years as far back as 1927 (Accident Facts, 1995, 1996, 1997 editions). The estimated number of pedestrian fatalities for 1927 was 10,820, as shown in table 4. The pedestrian death count irregularly grew until 1937, when 15,500 pedestrian deaths were reported, the largest number in U.S. history. Thereafter, the number declined. The number of pedestrian fatalities exceeded 10,000 during 1969, 1972, and 1973, and since then decreased to 6,100 in 1996. It should be noted that the NSC estimating procedure was changed in 1987 and the annual number of deaths it reported became substantially lower beginning that year.

It is also of interest to consider pedestrian fatalities as a percentage of total traffic fatalities. During 1927, pedestrian deaths accounted for 41.9 percent of total traffic deaths. That percentage has declined and was 14.1 percent of the total in 1996, a substantial decline from 1927 (figure 5). Increased travel by car is one factor in that change. Evans (1991), among others, has reported that the higher the degree of motorization in a country, the number of motor vehicles per 100,000 population, the lower the proportion of pedestrian deaths to total traffic deaths. The proportion of pedestrian deaths declined as the United States progressively became more motorized. This trend also is seen in less motorized countries (Choueiri et al., 1993).

This influence of car travel was highlighted by the U.S. experience during World War II when there was an interruption in the steady decline in pedestrian fatalities as a percentage of total traffic fatalities. The pedestrian fatalities were 33.9 percent in 1941. During the war years (1942-1945) the total abruptly jumped to values between 38 and 41 percent. In 1947, the figure reversed again to a new low of 32 percent, and after 1949 did not again reach 30 percent (See table 4). The increase during World War II probably reflected the fact that motor vehicle mileage fell during those years because civilian vehicle production gave way to military needs, and the existing civilian motor vehicle fleet amassed drastically fewer miles because of gasoline and tire (that is, rubber) rationing. It is also likely that the characteristics of highway users changed during that period, what with millions of young men away in the military, plus unprecedented numbers of women in the work force. It should be noted that Choueiri et al. (1993) show a greater pedestrian death decline in Europe during recent years than in the United States.

Table 5 shows a comparison of States (and Puerto Rico), using NHTSA data (Traffic Safety Facts, 1995) from highest rank to lowest according to pedestrian deaths per 100,000 population. The table is reproduced here to suggest some of the complexities that underlie pedestrian crash and death figures. The 10 States with the highest pedestrian death rate per 100,000 population vary significantly: two are urban and densely populated (DC and Puerto Rico), 3 are sparsely populated desert states, and 3 are among the 11 most populous states (California, Florida, and North Carolina). This suggests that the complex of factors producing high pedestrian death rates may differ from one State to another. Also, none of these rates consider pedestrian exposure or vehicle exposure, the proportion of pedestrians by age, or many other possible contributing factors.

At the other end of the spectrum, the 10 States with the lowest pedestrian death rate per 100,000 population also differ. The lowest 10 include rural States, cold weather States, industrial heartland states, and the agricultural midwest. This may be indicative of lower amounts of walking by pedestrians and/or less pedestrian interaction with high volumes of motor vehicles.

When Do Pedestrian Collisions Occur?

A. TIME OF DAY

Collisions can and do occur at any time, but there are trends involving the time of occurrence. Table 6 shows how pedestrian crashes, injuries, and fatalities vary by time of day.

Figure 5. Pedestrian as a percentage of total traffic fatalities, 1927-1996

Table 6 can be used to contrast the time of occurrence for "all" pedestrian crashes, fatally injured pedestrians, and pedestrians injured but not killed.

Figure 6. A disproportionately high percentage of pedestrian deaths occur at night.

Among the sample of pedestrian collisions (Hunter et al., 1996), 62 percent happened during the day between 6:00 a.m. and 6:00 p.m. Consistent with those daytime numbers are other findings, based on data from urban areas. These show general agreement that the peak time for pedestrian crashes is between 3 p.m. and 6 p.m. This peak represents about 30 to 40 percent of the collisions (Fatal Accident Reporting System, 1990; Knoblauch, 1977; Davis and Huelke, 1969; Cove, 1990) and the proportion decreases on either side of this period. Smaller secondary peaks from 7 a.m. to 9 a.m. and Noon to 1 p.m. were reported by Smeed (1968).

NHTSA figures (Traffic Safety Facts, 1995) show that the distribution by time of occurrence for pedestrian injuriesis somewhat similar to that of all collisions (about 63 percent of injuries concentrated from 6:00 a.m. to 6:00 p.m., compared with 61 percent for all collisions). This was also reported by Cove (1990), showing pedestrian injury crashes to have a major peak between 3 p.m. and 7 p.m. and a minor peak between 7 a.m. and 9 a.m., based on data from the National Accident Sampling System (see figure 7).

Figure 7. Pedestrian injuries by time of day for urban and rural land use.

The time distribution of pedestrian fatalities stands in sharp contrast to the above. Among pedestrian fatalities, 62 percent happened at night (table 6). Fatal pedestrian crashes peak in the evening hours (Cove, 1990), between 5 and 11 p.m., including one minor peak from midnight to 2 a.m. (See figure 8).

This trend in fatalities could be partly associated with rural pedestrian crashes involving high-speed vehicles and pedestrians walking along a dark road or in some cases lying unconscious (sleeping) in the road. In fact, in North Carolina, 10 percent of all pedestrian fatalities involve a pedestrian lying in the road (North Carolina Traffic Accident Facts, 1990). Thus, the role of alcohol among adults is thought to be involved in nighttime pedestrian fatalities. Fatality figures suggest that the victim profile would vary by time of day. Alcohol is a greater factor at night, but children are less likely to be involved at night.

Both the severity of pedestrian injury and the type of pedestrian crash vary by time of day. Data from six states, reported by Hunter et al. (1996), illustrate this point. Based on a sample of all pedestrian crashes, table 7 shows a breakdown of pedestrian crash types according to four different light conditions (i.e., related to time of day), distributed as follows:

These four categories create a rough scale from the greatest amount of light (daylight) to the least (dark, street not lighted), thus partly related to time of day, and table 7 shows the crash types that are most frequent under each light condition. Though daylight hours account for about 61 percent of all crashes in Hunter's study, more than 70 percent of some types of crashes occur in the daytime (e.g., 73 percent of pedestrian crashes related to buses occur in daylight).

Although unlit rural streets and roads might be considered a considerable hazard for pedestrians, the data in table 7 show that these conditions account for a much smaller percent of all crashes than, for example, walking along a roadway in daylight.

Figure 8. Pedestrian fatalities by time of day for urban and rural land use. Source: Cove, 1990.

The nighttime association with fatal crashes is emphasized in a study of the effects of daylight savings time (DST) (Ferguson et al., 1995). This study asserts that if DST were retained year-round, approximately 900 additional traffic deaths would be avoided (727 pedestrians and 174 motor vehicle occupants, say the authors) because the DST clock setting results in more daylight at the end of the day, when fatal crashes are more likely, an advantage that is apparently not fully offset by the comparably less daylight during the morning hours.

B. DAY OF WEEK

Pedestrian crashes also vary by day of week. Available data indicate that pedestrian crashes are overrepresented on Friday and Saturday and are underrepresented on Sunday. These trends may be related to such factors as: the amount of walking by day of week; less pedestrian interaction with rush-hour traffic; and/or less late-night drinking and walking. A Wayne County, MI, study (Davis and Huelke, 1969) reported that 35 percent of the crashes there occurred on Friday and Saturday. This was especially true for children, with Friday being the highest crash day. Similar patterns were found for urban, suburban, and rural data samples from a number of U.S. cities and counties (Knoblauch, 1977). The highest overrepresentation of pedestrian crashes was on Friday.

Data dealing with pedestrian fatalities also reveal that Friday and Saturday have the greatest percentages of such crashes for both rural and urban areas, with pedestrian fatalities nearly constant for Sunday through Wednesday (see figure 9). Pedestrian crashes resulting in non-fatal injuries were most prevalent on Fridays and lowest on Sundays (Cove, 1990).

Figure 9. Pedestrian fatalities by day of week for urban and rural land use. Source: Cove, 1990.

C. MONTH OF YEAR

Beyond the trends by hour of day and day of week, there are also differences in U.S. pedestrian crashes by season of year, mediated in part by factors related to pedestrian age. Figure 10 shows that among older pedestrians, more crashes occur during the fall and winter months, whereas among younger pedestrians more occur during the spring and summer (Zegeer et al., 1993).

Consistent with the above, a study conducted in Wayne County, MI (Davis and Huelke, 1969) showed that more pedestrians (13 percent) were killed during December than in any other month. A study of rural and urban data samples of U.S. areas (Knoblauch, 1977) showed December to be the month having the greatest overrepresentation. Nationwide pedestrian fatalities in 1989 were found to be highest in September through January (Figure 11), months with fewer daylight hours and more inclement weather.

Figure 10. Pedestrian crashes by age and occurring in fall or winter months. (September-February). Source: Cove, 1990.

Figure 11. Pedestrian fatalities by month. Source: Cove, 1990.

D. SUMMARY: WHEN DO PEDESTRIAN COLLISIONS OCCUR?

1. Fatal pedestrian crashes tend to occur during nighttime hours.
2. Non-fatal pedestrian crashes tend to occur during daytime hours.
3. Pedestrian crashes are more frequent on Friday and Saturday and less frequent on Sunday.
4. Child-pedestrian crashes occur more often during summer.
5. Adult pedestrian crashes occur more often in the winter.
6. Type of pedestrian crashes also varies with time of day, day of week, and season.

Who Is Involved in Pedestrian Crashes?

A. AGE

Table 8 shows that the largest percentage of pedestrian deaths is seen for the two age groups that span the 25-44 year age range. A total of 31.8 percent (15.4 percent + 16.4 percent) of pedestrian fatalities occur in this age range, a greater percentage than for the 5 preceding age groups combined. (Note the varying age intervals used in this table prepared by NHTSA [Traffic Accident Facts, 1995.] The 25-34 age category spans 10 years while the next lower category (21-24) only covers 4 years. Thus, the 15.4 percent of fatalities that falls in the 25-34 year category is not as much greater as might appear when compared with the next younger category, since the latter includes data from less than half as many years. Note also that 13.9 percent of fatalities fall in the oldest category [greater than 75 years old]; however, the open-ended age span of this category includes data from more years than the immediately preceding category. Overall, more than twice as many male pedestrians (3742) are killed as female (1727) pedestrians.

The final column shows fatalities expressed as deaths per 100,000 persons in a given age category. The oldest age category stands in greatest contrast to the rest.

The oldest age category does not contrast as sharply to the next younger age groups in terms of injury statistics (non-fatal). This may stem in part from the fact that older pedestrians are more likely to succumb to their injuries than younger adults. Children may be more likely to survive collisions on lower speed neighborhood streets. The difference in injuries between male and female pedestrians is less than that for fatalities. The ratio of male/female pedestrian injuries is 1.4 while the ratio of male/female pedestrian deaths is 2.2.

For "all" pedestrian crashes (Hunter et al., 1996), the distribution by age is more similar to injury crashes than to fatal crashes. Also, the ratio of male to female differs. In fatal crashes, there are more males in every age category, but in "all" crashes, males make up fewer than half of the cases in several age categories, including the 10-20 year age range and the categories that include persons 55 years old and older. In this database, 61 percent of the pedestrians involved in a collision were males. In short, samples of fatal pedestrian crashes are more likely to involve males and ages 25-54 compared to nonfatal pedestrian crashes.