2000 SURVEY OF FRONT SEAT OCCUPANT RESTRAINT USE IN EIGHTEEN TEXAS CITIES

January 2001

This report was prepared in cooperation with the

Traffic Operations Division Texas Department of Transportation

Jeanne Swanson and Chris Willrich, Project Managers

National Highway Traffic Safety Administration U.S. Department of Transportation

DISCLAIMER

"The conclusions and opinions expressed in this document are those of the author, and do not necessarily represent those of the State of Texas, the Texas Department of Transportation or any political subdivision of the State or Federal Government."

ii

TABLE OF CONTENTS

PAGE

BACKGROUND..................................................................................................... 1

STUDY METHOD.................................................................................................. 2

RESULTS OF THE 2000 SURVEY....................................................................... 4

LONGITUDINAL LOOK...................................................................................... 11

CONCLUSIONS..................................................................................................... 21

SUMMARY............................................................................................................ 23

REFERENCES........................................................................................................ 25

iii

LIST OF TABLES

PAGE

TABLE 1 2000 OCCUPANT RESTRAINT USE BY GENDER................................... 4

TABLE 2 2000 DRIVER RESTRAINT USE BY AGE.................................................. 5

TABLE 3 2000 PASSENGER RESTRAINT USE BY AGE.......................................... 5

TABLE 4 2000 PERCENTAGE OF RESTRAINED DRIVERS BY AGE AND GENDER............................................................................... 6

TABLE 5 2000 PERCENTAGE OF RESTRAINED PASSENGERS BY AGE AND GENDER............................................................................... 6

TABLE 6 2000 OCCUPANT RESTRAINT USE BY VEHICLE TYPE....................................................................................... 7

TABLE 7 ASSOCIATION BETWEEN DRIVER AND PASSENGER RESTRAINT USE ................................................................................... ~....... 8

TABLE 8 2000 PERCENTAGE OCCUPANT RESTRAINT USE IN THE 18 STUDY CITIES............................................................................ 9

TABLE 9 2000 PERCENTAGE DRIVER AND PASSENGER RESTRAINT USE IN THE 18 STUDY CITIES............................................ 10

TABLE 10 COMPARISON OF 1999 AND 2000 OCCUPANT RESTRAINT USE IN THE 18 STUDY CITIES................................................... 13

TABLE 11 PERCENT OF DRIVERS RESTRAINED BY CITY OVER TIME.................................................................................................... 15

TABLE 12 PERCENT OF PASSENGERS RESTRAINED BY CITY OVER TIME.................................................................................................... 16

TABLE 13 DRIVER AND PASSENGER RESTRAINT USE BY GENDER ANDYEAR.................................................................................................... 17

TABLE 14 DRIVER RESTRAINT USE OVER TIME BY AGE AND GENDER................................................................................ 20

iv

LIST OF FIGURES

PAGE

FIGURE 1 STUDY CITIES IN THE TEXAS SAFETY BELT OBSERVATIONAL SURVEY........................................................ 3

FIGURE 2 FRONT SEAT OCCUPANT RESTRAINT USE BY YEAR.......... 14

FIGURE 3 DRIVER RESTRAINT USE BY AGE AND YEAR.................... 19

v

1.....----------------------------~~-~~~-~------

2000 SURVEY OF FRONT SEAT OCCUPANT RESTRAINT USE IN EIGHTEEN TEXAS CITIES

Background

A mandatory belt use law (MUL)-was-passed--in-the 1985 general session of the Texas

Legislature and went into effect without sanctions September 1, 1985. Enforcement with the

imposition of fines began on December 1, 1985. This law requires drivers and front seat passengers

to use safety belts. Drivers are responsible for passengers under 15 years of age, and may be issued a

citation for a front seat minor passenger's failure to use a safety belt. The Texas MUL was amended

in 1999 to include passengers under 15 years of age occupying any seat in the vehicle equipped with

a safety belt. These requirements apply to passenger cars and light pick-up trucks of not more than

3/4-ton carrying capacity. It exempts persons for medical reasons (requiring a written statement

from a licensed physician), postal employees in box-to-box delivery of mail, and employees of

public or private utility companies who are engaged in meter reading or similar duty requiring

frequent entry and exit from a vehicle. Use or non-use of safety belts is not admissible evidence in a

civil trial. The fine for non-compliance is $25 - $50. The Texas MUL allows for primary

enforcement.

In 1984, the Texas Transportation Institute (TTl) began collecting occupant restraint use data

in a sample of Texas cities for the Texas Department of Transportation (TxDOT). At that time

occupant restraint legislation was not under consideration in Texas. It was agreed, however, that

collecting baseline data on occupant restraint use would prove beneficial for information purposes in

response to legislative initiative. The background, methodology and results of the baseline study, as

well as a review of other relevant studies, were presented in a 1985 TTl report (Hatfield, et al.,

1985).

In order to assess changes in occupant restraint use after passage of the law and to provide

current usage rates, TTl has continued to conduct observational surveys each year since the MUL has

been in effect. From 1987 through 1990, data was collected at two intervals annually (January and

1

June). From 1991 through 2000, the survey was conducted at one interval during late spring/early

summer. The 2000 survey was conducted beginning May 20 and continuing through the month of

June. This report presents the results ofthe 2000 survey, and compares these findings with the

results of previous surveys.

Study Method

For the 1985 pre-law observational survey 12 Texas cities were selected to represent the

major population centers in the East, Central, and Gulf Coast regions of the State, as well as the less

populated areas of West Texas, the Panhandle, and the Rio Grande Valley. At the request of

TxDOT, two additional cities were included in the 1986 post-law survey and four additional cities

were included in the 1988 post-law survey. Figure 1 shows the sample of 18 cities currently used as

observation sites.

In each study city, six sites were selected to represent a geographic cross-section ofthe city.

Each intersection selected for observation was controlled by either a stop sign or traffic signal, and

on roadways with sufficient traffic volume such that 200 vehicles could be observed within an hour

or less time. All observations were recorded during daylight hours and on weekdays.

Observations were limited to drivers and right front seat (outboard) passengers, with restraint

use determined by the use of a shoulder harness. Eligible vehicles included passenger cars and

standard size or light duty pick-up trucks.

The following information was collected for each eligible vehicle:

• Driver and front seat outboard passenger restraint use (yes or no)

• Front seat occupant gender (male or female)

• Estimated driver age (15-19, 20-60, 61+)

• Estimated front outboard passenger age (0-4, 5-14, 15-19,20-60, 61+)*

• Pick-up truck (yes or no)

* No information on passengers under 15 was recorded in the 1985 baseline study.

2

FIGURE 1 STUDY CITIES IN THE SAFETY BELT OBSERVATIONAL SURVEY

El Paso

• Amarillo

• • Wichita Falls Lubbock

Ft. Worth • • Dallas Abilene • •Tyler

• Midland

3

• Waco

Bryan/College Station •

Austin •

• San Antonio

TTl project staff and Texas A&M University students conducted the observations. Each

observer was provided individual instruction and field training by TTl project staff. To assure

accuracy of data collection, observers were monitored during the survey period by the study staff.

Results of the 2000 Survey

In the combined 18-city sample, data regarding 26,942 front seat occupants were

collected at a total of 108 intersections. The percentage of front seat occupants restrained in

these urban area locations was 79.0. 80.6 percent of the drivers and 73.0 percent of the

passengers observed were using safety belts.

Analysis of the sites in each city where detailed data were collected revealed a higher usage

rate for females than males. As shown in Table 1, female drivers and passengers were restrained

over 7 percentage points more often than male drivers and passengers (84.9 percent compared to

77.5 percent for drivers and 76.9 percent compared to 68.0 percent for passengers).

TABLE 1. 2000 OCCUPANT RESTRAINT USE BY GENDER

Driver Passenger

Male Female Male Female

% Restrained 77.5 84.9 68.0 76.9

%Unrestrained 22.5 15.1 32.0 23.1

Total Occupants (N) 12,318 8,937 2,528 3,159

4

The driver restraint usage rate increased as age increased. The restraint usage rate for drivers

over age 60 was 82.4 percent compared to 77.4 percent for teenage drivers (Table 2). For

passengers, the relationship between age and restraint use was similar. Generally, restraint use

increased as age increased (Table 3). The age group with the lowest passenger restraint use was

infants and young children (0 to 4 years). The sample size forthis group was very small (81), and

only 45.7 percent of those observed were restrained. Teen passengers were restrained only slightly

less often than passengers in the 5 to 14 year age group (68.0 percent and 69.3 percent, respectively).

As with drivers, older passengers were most often restrained.

TABLE 2. 2000 DRIVER RESTRAINT USE BY AGE

Driver Age

15-19 20-60 Over60

%Restrained 77.4 80.4 82.4

0/o Unrestrained 22.6 19.6 17.6

Total Drivers (N) 610 18,013 2,632

TABLE 3. 2000 PASSENGER RESTRAINT USE BY AGE

Passenger Age

0- 4* 5-14 15-19 20-60 Over60

% Restrained 45.7 69.3 68.0 73.6 80.9

%Unrestrained 54.3 30.7 32.0 26.4 19.1

Total Passengers (N) 81 655 723 3,475 753

*Restramt use was considered either safety belt or child safety seat.

5

Cross-classification of the data by age and gender (Table 4) revealed that female drivers are

more likely than male drivers to wear safety belts at every age level. The difference in usage rates by

males and females were most pronounced within the 20 to 60 year age group, and least pronounced

among teens.

TABLE 4. 2000 PERCENTAGE OF RESTRAINED DRIVERS BY AGE AND GENDER

Driver Gender

Driver Age Male Female

15-19 (n=610) 74.3 80.3

20- 60 (n=l8,013) 77.2 84.9

Over 60 (n=2,632) 80.1 86.5

Restraint use among passengers was also analyzed by gender and age (Table 5). The highest

restraint use was evidenced by females over 60 (83.2 percent). Females 0 to 4 years evidenced the

lowest level ofuse (40.6 percent).

TABLE 5. 2000 PERCENTAGE OF RESTRAINED PASSENGERS BY AGE AND GENDER

Passenger Gender

Passenger Age Male Female

0- 4 (n=81) 49.0 40.6

5- 14 (n=655) 68.1 70.7

15- 19 (n=723) 60.8 74.5

20- 60 (n=3,475) 68.9 77.3

Over 60 (n=753) 75.8 83.2

6

For both drivers and passengers, restraint use was found to be higher for occupants of

passenger cars than for pick-up trucks, as seen in Table 6. The difference was 8.5 percentage points

for drivers and 7.6 percentage points for passengers.

TABLE 6. 2000 OCCUPANT RESTRAINT USE BY VEHICLE TYPE

Driver Passenger I

Car Pick-up Car Pick-up

% Restrained 82.6 74.1 74.6 67.0

%Unrestrained 17.4 25.9 25.4 33.0

Total Occupants (N) 16,168 5,087 4,448 1,239

As was true in previous surveys, there was a strong association between driver restraint use

and passenger restraint use, often referred to as the audience effect. In the 2000 survey, 26.4 percent

of all vehicles observed had a passenger in the front outboard seating position. In this sample of

5,610 vehicles, if the driver was restrained, it was very likely that the passenger was also restrained

(81.8 percent of the time). Likewise, if the driver was unrestrained, it was likely that the passenger

was· also unrestrained (62.2 percent of the time). Restrained passengers were riding with

unrestrained drivers only 37.8 percent of the time (Table 7).

7

TABLE 7. ASSOCIATION BETWEEN DRIVER AND PASSENGER RESTRAINT USE

Drivers Restrained Passengers Restrained

%Unrestrained % Restrained Total

%Unrestrained 62.2 (676) 37.8 (411) 100 (1087)

% Restrained 18.2 (821) 81.8 (3702) 100 (4523)

Table 8 shows the observed restraint usage rate for each of the 18 cities using data from the 6

sites used to represent geographic cross sections of each city. These estimates provide the usage rate

for all front seat occupants observed in each city and does not differentiate among drivers and

passengers. Citywide occupant restraint use ranged from a low of 68.7 percent in Abilene to a high

of 88.5 percent in Amarillo. Eight of the 18 cities had usage rates above 80 percent for drivers and

passengers in passenger cars and pick-ups combined.

The data that provided information regarding driver and passenger were analyzed separately

for each of the 18 cities. Table 9 shows that driver restraint use ranged from a low of70.5 percent in

Abilene to a high of89.9 percent in Amarillo. Passenger restraint use ranged from 61.2 percent in

Abilene to 83.5 percent in Austin. The total percentage of drivers restrained was greater than the

observed percentage of passengers restrained, with an average difference of approximately 7.5

percentage points.

8

TABLE 8. 2000 PERCENTAGE OCCUPANT RESTRAINT USE IN THE 18 STUDY CITIES

Number Percent City Observed Restrained

Abilene 1,491 68.7

Amarillo 1,498 88.5

Austin 1,478 83.6

Beaumont 1,540 79.6

Brownsville 1,327 78.2

Bryan/College Station 1,504 80.6

Corpus Christi 1,531 81.1

Dallas 1,482 76.9

El Paso 1,569 81.2

Ft. Worth 1,404 72.6

Houston 1,473 77.2

Laredo 1,605 78.7

Lubbock 1,502 84.6

Midland 1,477 81.6

San Antonio 1,550 73.7

Tyler 1,515 84.2

Waco 1,485 70.8

Wichita Falls 1,511 79.1

9

L_ ___________________________________________________ __

TABLE 9. 2000 PERCENTAGE DRIVER AND PASSENGER RESTRAINT USE IN THE 18 STUDY CITIES

City ........ ·--······ Drivers Passengers

Abilene 70.5 61.2

Amarillo 89.9 82.9

Austin 83.7 83.5

Beaumont 81.0 74.7

Brownsville 81.4 68.6

Bryan/College Station 82.6 73.1

Corpus Christi 81.3 80.4

Dallas 77.9 72.7

El Paso 83.8 72.6

Ft. Worth 74.7 65.9

Houston 78.0 73.6

Laredo 82.2 68.4

Lubbock 85.9 79.5

Midland 84.5 69.6

San Antonio 75.7 66.9

Tyler 85.1 80.8

Waco 72.0 66.1

Wichita Falls 80.1 75.3

10

Longitudinal Look

Conducting annual surveys of restraint use is useful for analyzing changes over time. It is

important when using longitudinal data to assure that the data are comparable over time. If the

variable being measured is not a fixed population, as in the traffic observed to collect restraint usage

data, comparability can be achieved by: 1) holding the sites and data collection procedures constant

within cities, or 2) by using identical sampling methods each year within cities. Neither of these

safeguards has been kept throughout the survey period from the beginning (1985) to the current wave

of data collection. The sites and data collection procedures were held constant from 1985 through

1991. However, the implementation of a statewide sampling methodology in 1992 introduced a

change in both the site selection and the data collection procedures used for the 18-city surveys. In

an effort to consolidate survey efforts, data representing citywide estimates were collected from sites

selected in the probability based sample design to estimate statewide restraint use. The data

collection procedure was also changed from a quota of observations per site to a time based volume

of observations per site. The result was that the 1992-1998 data for each city was not comparable to

the cross-sectional data of 1985-1991. Nevertheless, the 1992-1998 data was collected in such

manner as to describe a city-wide estimate of front seat restraint use, and was therefore reported and

analyzed in comparison with prior years' city-wide results. The 1999 survey of front seat occupant

restraint use in 18 Texas cities represented a transition back to a methodology that is more consistent

with the pre-1992 surveys. In the 1999 and 2000 surveys, a quota of observations were made at half

the number of sites ( 6) using similar methods as were used in each city in the 1985-1991 surveys.

This provides a snapshot look at restraint use in the 18 cities for 1999 and 2000 that represent

restraint use for a cross-section of each city, but is not statistically comparable (at the city level) to

results from years prior to 1999. Therefore, in this year's report the longitudinal look is restricted to

the presentation of results by year, and the trend analysis at the city level is limited to 2000

compared to 1999.

Table 10 shows the comparison of front seat occupant restraint use for 1999 and 2000.

Again, the sites included in this two-year comparison are matched. The sample size at each site was

increased in the 2000 survey from 150 vehicles per site to 200 vehicles per site. The statistical test

used to determine significant changes in belt use ( z-test referenced above) revealed that eight of the

11

18 cities increased in belt use from 1999 to 2000, four of the 18 cities decreased in belt use, and the

belt use rates in six cities stayed statistically the same. Increases were observed in Beaumont,

Brownsville, Corpus Christi, Dallas, Laredo, Lubbock, Tyler, and Wichita Falls. The largest

percentage point gain was seen in Lubbock (9 percentage points). Decreases were observed in

Abilene ( -4.1 percentage points), Bryan/College Station (-5.3 percentage points), San Antonio (-3. 8

percentage points), and Waco (-12.9 percentage points).

Figure 2 is a composite view of restraint use for each year using the various data collection

methods described above. The data used for this graph are from the combined sites across all cities,

and include driver and outboard passenger belt use. Tables 11 and 12 show driver and passenger

restraint use for each year in each city. Again, variations over time shown in these two tables may be

attributable in part by variations in the study methodology.

Table 13 shows changes over time in driver and passenger restraint use by males and females

for all cities included in the observational survey. These data show a drop in use by both males and

females following the first full year of the MUL. However, the drop in female restraint use was not

as large and rebounded more quickly than usage for males. Belt use among males and females in

1992 was approximately 10 percentage points higher than 1991. Again, the sites included in the

1992 survey were a subset of earlier surveys and therefore do not represent a replication of earlier

surveys. A significant decrease from the 1992 usage rate was observed in 1993 for males and

females. In 1994, however, the male and female driver restraint usage rate returned to approximate

the 1992 rate. A small, but statistically significant increase in belt use for male drivers was observed

in 1995. This increase for males was again observed in the 1997 survey and continued to be

observed in the 1998 survey. The usage rate for male drivers remained statistically the same in 1999

and in 2000. The female driver restraint use slipped to the 1996 level in 1999 and remained

statistically the same in 2000.

12

Table 10. COMPARISON OF 1999 AND 2000 OCCUPANT RESTRAINT USE IN THE 18 STUDY CITIES

1999 2000 Percentage

City Percent Percent Point

Restrained Restrained Change

Abilene 72.8 68.7 -4.1

Amarillo 89.1 88.5 NS*

Austin 84.8 83.6 NS*

Beaumont 75.0 79.6 +4.6

Brownsville 72.3 78.2 +5.9

Bryan/College Station 85.9 80.6 -5.3

Corpus Christi 76.7 81.1 +4.4

Dallas 72.9 76.9 +4.0

El Paso 84.0 81.2 NS*

Ft. Worth 72.2 72.6 NS*

Houston 76.0 77.2 NS*

Laredo 70.1 78.7 +8.6

Lubbock 75.6 84.6 +9.0

Midland 82.3 81.6 NS*

San Antonio 77.5 73.7 -3.8

Tyler 80.7 84.2 +3.5

Waco 83.7 70.8 -12.9

Wichita Falls 75.4 79.1 +3.7

*Change is not statistically significant.

13

1-' .j::--

Figure 2. Front Seat Occupant Restraint Use in Texas Over Time

90~----------------------------------------------------------------------------------~

80 78.0 79.0

72.4 73.3 73.9

69.0 68.8 70+---~~------------------------------~~~~~~----~

60 -t---1 58.2 58.6 59.2 61.3

52.1

50 +---1

40 -t---1

30 I 11111!1-----l

20 4.2

10

0

1985 1986 Jan- Jun- Jan- Jun- Jan-

87 87 88 88 89 Jun- Jan-

89 90 Jun- 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 90

1-' \JI

City

Abilene

Amarillo

Austin

Beaumont

Brownsville

Bryan/CS

Corpus Christi

Dallas

El Paso

Ft. Worth

Houston

Laredo

Lubbock

Midland

San Antonio

Tyler

Waco

Wichita Falls

Average

1985

NA

10.8

28.1

NA

3.4

16.4

13.4

20.6

15.0

NA

19.7

NA

14.3

NA

13.3

16.7

9.7

NA

15.2

TABLE 11. PERCENT OF DRIVERS RESTRAINED BY CITY OVER TIME

1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996

NA NA 52.8 57.3 63.7 69.3 75.6 73.8 71.9 75.5 78.4

65.2 66.2 60.4 57.8 61.4 61.7 71.2 72.4 75.9 70.0 70.4

74.6 74.3 72.7 70.1 76.8 79.1 81.2 81.2 85.0 88.7 86.1

60.0 52.0 59.3 65.2 72.0 73.5 66.8 75.4 71.0 63.7 64.8

63.3 43.6 35.9 51.5 63.5 68.9 NA 67.7 79.3 80.1 81.3

70.4 64.1 61.5 56.9 63.7 67.8 87.2 83.9 87.7 88.3 86.8

76.8 65.9 83.3 75.6 77.5 71.4 81.0 76.8 83.3 81.8 80.7

70.9 58.4 67.6 59.2 67.1 66.0 77.0 55.2 72.2 76.4 80.6

63.8 63.9 72.0 64.6 72.9 68.2 62.6 68.9 65.4 74.0 68.0

63.3 61.2 55.0 57.8 60.7 62.1 62.2 68.6 70.0 67.4 80.5

68.6 66.0 53.3 62.1 65.4 58.3 76.5 70.3 76.1 73.9 79.2

NA NA 50.1 61.8 73.0 78.4 71.0 72.8 71.9 78.0 76.7

63.3 57.6 61.0 66.4 72.0 60.5 82.4 78.8 85.7 77.8 76.0

NA NA 55.2 69.7 67.9 73.3 86.6 85.8 86.7 86.5 84.2

60.6 58.7 47.4 44.2 50.2 56.3 78.6 68.8 72.4 71.8 76.1

67.0 59.2 72.4 76.5 80.8 81.1 77.6 76.6 76.9 83.9 77.4

57.5 48.0 45.9 47.9 53.8 55.8 73.3 74.4 73.0 79.9 75.3

NA NA 59.9 56.3 73.6 64.2 71.6 72.8 74.8 75.9 76.3

66.8 60.5 59.2 61.2 67.6 67.5 77.3 74.5 77.2 78.7 78.0

1997 1998 1999 2000

77.1 74.5 74.9 70.5

82.9 87.5 89.8 89.9

87.5 90.7 86.9 83.7

70.9 75.5 78.0 81.0

77.8 77.2 73.8 81.4

87.4 87.5 86.4 82.6

82.7 84.1 78.9 81.3

73.9 73.8 72.5 77.9

74.4 83.5 85.4 83.8

75.8 80.1 73.4 74.7

81.3 75.3 76.8 78.0

79.0 73.1 72.2 82.2

76.2 78.3 77.3 85.9

80.3 83.5 84.3 84.5

75.1 76.8 80.0 75.7

83.9 83.9 81.5 85.1

78.0 78.0 84.2 72.0

71.0 76.9 74.9 80.1

79.4 80.8 79.5 80.6

..... "'

City

Abilene

Amarillo

Austin

Beaumont

Brownsville

Bryan/CS

Corpus Christi

Dallas

El Paso

Ft. Worth

Houston

Laredo

Lubbock

Midland

San Antonio

Tyler

Waco

Wichita Falls

Average

1985

NA

8.7

18.1

NA

2.9

14.7

8.2

11.9

11.4

NA

8.2

NA

9.3

NA

4.9

12.1

6.7

NA

9.6

TABLE 12. PERCENT OF PASSENGERS RESTRAINED BY CITY OVER TIME

1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996

NA NA 39.2 52.6 61.6 67.2 69.0 62.1 63.9 73.2 74.6

55.8 52.4 46.8 41.8 51.2 53.3 67.0 67.0 68.0 60.1 67.2

60.5 64.4 67.3 60.3 65.4 73.4 69.7 76.8 77.7 84.2 90.8

47.2 45.5 50.9 54.3 62.0 66.0 61.5 67.4 74.2 49.3 60.9

54.6 32.5 24.1 35.1 43.3 50.1 NA 56.2 63.3 69.6 70.0

60.4 58.1 58.3 56.5 53.8 58.3 78.0 76.5 75.8 79.8 84.7

67.0 59.3 75.2 67.4 67.3 62.1 71.7 62.7 70.0 69.6 70.1

68.3 47.2 54.0 55.7 55.3 58.1 54.8 49.2 68.7 66.0 63.4

60.3 60.7 58.8 49.6 60.1 54.6 53.2 56.4 56.7 68.2 55.6

54.0 53.2 45.9 48.1 50.2 46.4 34.8 56.8 75.8 61.8 89.4

6.6 59.6 52.6 52.9 49.7 42.9 76.1 62.9 66.7 69.8 68.2

NA NA 42.7 52.9 55.8 67.4 59.0 61.3 55.2 63.7 62.4

53.0 50.8 40.9 44.1 57.5 51.7 72.8 71.8 72.1 69.9 73.4

NA NA 40.2 56.5 65.1 56.9 80.6 67.4 79.3 78.2 68.5

46.6 44.4 32.2 35.6 34.2 41.6 67.7 59.2 71.4 59.8 69.1

56.9 48.8 64.3 72.8 69.7 76.4 65.8 62.9 68.7 79.8 71.4

49.2 35.3 32.3 36.4 47.1 41.1 65.3 82.1 73.3 76.8 84.5

NA NA 46.2 48.1 67.0 56.5 53.5 61.5 59.7 54.8 70.7

58.7 51.1 48.2 50.7 55.0 56.1 67.4 64.2 68.3 69.7 71.0

1997 1998 1999 2000

68.6 68.2 63.9 61.2

77.1 81.8 86.2 82.9

83.5 82.1 75.0 83.5

62.9 66.3 62.7 74.7

58.8 59.1 67.3 68.6

79.5 79.2 83.2 73.1

77.0 80.4 67.8 80.4

65.7 75.8 74.2 72.7

59.5 74.5 79.2 72.6

77.0 78.9 68.1 65.9

84.1 73.3 73.1 73.6

66.7 60.5 63.5 68.4

69.9 76.6 68.7 79.5

72.5 76.2 72.7 69.6

66.2 70.2 69.1 66.9

78.0 71.3 77.7 80.8

71.8 75.3 81.7 66.1

58.6 67.2 76.8 75.3

71.1 73.4 72.6 73.1

TABLE 13. DRIVER AND PASSENGER RESTRAINT USE BY GENDER AND YEAR

Percent Restrained Percent Restrained

Year Drivers Passengers

Male Feniale-- ·· Male Female

1985 13.8 16.9 7.5 10.8

1986 64.8 67.8 55.1 58.0

1987 (June) 57.0 63.8 44.7 53.4

1988 (June) 54.9 64.7 42.2 50.0

1989 (June) 57.2 66.3 45.4 54.8

1990 (June) 64.2 71.8 52.1 57.1

1991 63.9 72.3 51.6 59.1

1992 73.5 82.7 60.0 72.6

1993 70.1 80.7 60.5 67.1

1994 73.2 83.0 62.4 72.6

1995 74.9 84.1 63.0 74.5

1996 73.8 83.8 67.1 73.7

1997 75.2 85.0 66.8 74.4

1998 76.8 86.2 67.4 77.6

1999 76.4 83.9 68.3 76.0

2000 77.5 84.9 68.0 76.9

Table 13 also shows a similar trend in restraint use for male and female passengers over time.

As with drivers, male passengers were less likely to be belted prior to safety belt legislation (7 .5

percent male passengers restrained and 10.8 percent female passengers restrained in 1985). Male

passenger usage dropped to a greater degree after the first year of the enactment period (from 55.1

17

percent in 1986 to 44.7 percent in 1987, compared to 58.0 and 53.4 percent for female passengers).

The decrease in passenger restraint use from June of 1987 to June of 1988 was significantly smaller

for both males and females. The slow downward trend was reversed for both male and female

passengers in 1989. The trend of gradual increases in passenger restraint use for both males and

females has continued in the 90's. The slight changes observed in 2000 were not statistically

significant.

Changes in restraint use by the three age groups over time were also analyzed. The results

revealed that the oldest group of drivers (over 60 years) showed the highest increase in belt use for

the first year after the law went into effect (52 percentage points) and the lowest decrease in belt use

during the second year (four percentage points) compared to the other two age groups (Figure 3).

Although teen restraint use steadily decreased since 1986, a dramatic increase occurred in 1989 and

continued in 1990 and 1991 for teen belt use. Adult and senior use both increased significantly in

1990 (adults by 6.5 percentage points and seniors by 5.0 percentage points) and did not significantly

change in 1991. In 1992, all three age groups experienced significant increases. However, in 1993,

teen and older driver restraint use remained constant, while the adult age 20 to 60 group significantly

increased restraint use. Both teens and adults showed increases in restraint use in 1994, while no

change was observed in senior belt use. In 1995 a significant increase in adult belt use was

observed, while teenage and senior belt use stayed statistically the same. Adult belt use returned to

the 1994 level in 1996. The adult category significantly increased again in 1997 and 1998, and teen

belt use increased dramatically in 1998. However, in 1999 belt use among teens returned to the pre-

1998 level, and adult belt use significantly decreased. Belt use among all three age categories was

statistically the same in 2000 as in 1999.

18

1-' 1.0

100

80

60

40

20

0

%

85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 4

--e- Teen +Adult -$-Senior

Figure 3. Driver Restraint Use By Age and Year

When gender and age were analyzed together (Table 14), the results show that through the

years male and female drivers at each age level have seldom shown the same belt wearing behavior.

With some exceptions in some years, females in each age group were restrained more often than

males. Note that teen and adult males and adult females increased as a group from 1999 belt use

rates. Decreases in teen female and senior male and. female belt use percentages were quite small

and not statistically significant.

Year

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

TABLE 14. DRIVER RESTRAINT USE OVER TIME BY AGE AND GENDER

Percent Restrained By Age and Gender

15-19 20-60 Over60

Male Female Male Female Male Female

6.5 12.0 13.8 16.9 15.9 18.3

46.9 51.9 64.9 68.0 68.8 69.3

45.1 44.0 56.9 63.7 61.8 69.3

38.9 46.8 54.8 59.7 63.0 72.6

51.0 61.9 57.0 66.3 63.6 69.5

54.9 63.4 64.3 71.9 67.7 74.2

53.1 60.7 64.0 72.4 67.0 74.6

65.5 73.9 73.3 82.6 77.4 85.5

64.5 71.0 69.7 80.7 75.7 84.0

72.6 79.4 72.7 83.0 78.3 84.4

70.4 69.2 74.8 84.3 76.8 84.5

72.0 81.4 73.4 83.6 79.5 87.9

68.7 79.0 75.0 85.0 79.5 85.9

72.2 91.2 76.4 85.8 81.9 88.8

72.0 81.1 76.1 83.7 80.7 86.6

74.3 80.3 77.2 84.9 80.1 86.5

20

Conclusions

The initial survey of 1985 showed front seat occupant restraint use in 12 Texas cities

averaging 14.2 percent for all front seat occupants observed. Not surprisingly, a dramatic increase in

belt use was observed during the first year of the post-MUL period. Restraint use rates in the 1986

survey were 64.9 percent overall. At that time, compliance was considerably higher than reported

usage rates in other MUL States.

In the second year of the post-law period (1987), observed usage rates for front seat

occupants decreased by approximately seven percent to a 57 percent usage rate for all cities

combined. During this second year of MUL experience, decreases in use were attributed to those

segments of the population that were least likely to be restrained prior to seat belt legislation.

Specifically, males, teens, and pick-up occupants showed the largest decreases in use.

The January survey of 1988 seemed to support further evidence of the post-law decline. The

average belt use rate of 52 percent for 18 cities surveyed in January of 1988 was six percentage

points lower than June of 1987. One factor contributing to the decrease was the inclusion of the four

additional cities for this survey wave. Without the new cities the 14-city average was 55.7 percent.

Observed usage rates rose to an average of 56.9 percent for the 18 cities surveyed in June of

1988. As with the downward shift from June of 1987 to June of 1988, this upward change may have

been due in part to normal fluctuations in the data.

The 1989 survey indicated a leveling off for the average restraint usage rate across the 18

study cities of 59 percent. Three survey waves (June 1988 through June 1989) reflected a

consistency in the overall restraint use average that, incidentally, was not reflected uniformly at the

city level.

21

The 1990 survey revealed a significant increase in safety belt use. The average percentage of

front seat occupants restrained across all 18 cities was the highest ever observed in the June survey

wave. Every city in the sample experienced an increase in driver restraint use from June of 1989 to

June of 1990, with the exception of Midland (which experienced a statistically non-significant

decrease in use). Eight of the 18 cities reached the national (NHTSA) and state (TxDOT) target goal

of70 percent by 1990.

No significant changes in the combined 18-city safety belt use rate were revealed in the 1991

survey from June of 1990. At the city level, six cities showed increases and five cities showed

decreases in belt use. Six of the 18 cities surveyed sustained a usage rate above 70 percent.

The 1992 survey revealed significant increases in front seat restraint use in 11 cities. Five of

these cities showed increases in driver restraint use by over 15 percentage points. Eight of the 18

cities surveyed in 1992 sustained a usage rate above 70 percent, and of those, three had over 80

percent restraint use by front seat occupants.

A statistically significant change in the combined 18-city safety belt use rate was not

observed in 1993 from the overall rate observed in 1992. At the city level, only one city increased in

driver usage in 1993, whereas four cities had statistically significant decreases. In 1993, 12 of the 18

cities had occupant restraint usage rates above 70 percent, and two cities had usage rates above 80

percent.

Statistically significant increases in the combined 18-city safety belt use rates were observed

in 1994, 1995, 1996, and 1997. The safety belt use rate for front seat occupants in 1998 was

statistically equal to the estimate in 1997. All of the 18 cities had safety belt use rates above 70

percent in 1998, and seven cities were above 80 percent. The national goal of 85 percent by 2000

was attained in three cities. In 1999, the usage rate in the 18 urban areas increased again with

statistical significance. Using six sites to observe 900 vehicles in each city revealed that the 80

percent restraint usage rate for front seat occupants was attained in seven cities, as in 1998. Amarillo

22

and Bryan/College Station also surpassed the 2000 goal of 85 percent. In 2000, only Amarillo has

sustained the targeted goal of 85 percent or more front seat occupant restraint use. However, using

matched sites from the 1999 observations, eight of the 18 cities surveyed have surpassed the 80

percent usage rate.

Analysis of safety belt use for males and females and for the three age groups revealed

comparable patterns in the 2000 survey to previous observed usage patterns. Females evidenced

higher usage rates than males, both as drivers and as passengers. Teenage driver restraint use was

lowest, and senior driver restraint use was highest. An upward progression in belt use by age was

found for passengers. Infants were least likely to be restrained ( 45.7 percent) and passengers over 60

were most likely to be restrained (80.9 percent).

Occupants of cars (driver and passenger) were restrained 80.9 percent of the time. However,

occupants of pick-up trucks (driver and passenger) were restrained 72.7 percent of the time, a

difference of 8.2 percentage points. This gap in usage between occupants of cars and pickups is

larger than in the previous year.

As in earlier years, the audience effect was found to be quite strong. In other words, two

front seat occupants were shown to behave in a very similar manner in terms of restraint use--either

both individuals used the available restraint system, or both rode unrestrained. The gap between

driver restraint use and passenger restraint use was 7.6 percentage points, a difference that was larger

than the difference observed in 1998 and 1999, but consistent with the spread observed in previous

surveys.

SUMMARY

In summary, 2000 observation of occupant restraint use revealed an average usage rate across

the 18 cities of79.0 percent. Seventeen ofthe 18 cities in the sample had greater than 70 percent

usage rates for front seat occupants. Additionally, eight cities surveyed had greater than 80 percent

restraint usage for front seat occupants, which was established as a national target usage rate for

23

1994. The current national goal is for 85 percent restraint usage rate by the year 2000. This goal

was attained in Amarillo in 2000.

The collection of data specific to the occupants observed revealed that female drivers used

seat belts more often than male drivers, and female passengers were belted more often than male

passengers were belted. Young children and infants were least likely to be buckled as passengers.

Additionally, restraint use in cars was higher than restraint use in pick-up trucks.

24

REFERENCES

Hatfield, N.G., W.M. Hinshaw, N.G. Bunch, and R. Bremer, Observed Pre-Law Safety Belt Use by Adult Front Seat Occupants in Twelve Texas Cities, Texas Transportation Institute, Texas A&M University System, December, 1985.

Downie, N.M. and R.W. Heath, Basic Statistical Methods, Harper and Row, New York, NY, 1965.

25