U.S. Department of Transportation

National Highway Traffic Safety Administration

1200 New Jersey Avenue SE., Washington, DC 20590

TRAFFIC TECH

Technology Transfer Series

Number 394 September 2010

Seat Belt Use Rises in a Missouri County With 

A Primary Seat Belt Enforcement Ordinance

Statewide observed seat belt use has remained unchanged in

Missouri for the past several years. In 2007 Missouri’s usage

was 77%, five points below the nationalrate of 82% and 8 points

below the average rate of 85% in 15 States that upgraded their

seat belt laws since 1996. This plateau in usage occurred in spite

of regular and active participation in annual mobilizations. St.

Louis County has also participated regularly in high-visibility

enforcement (HVE) mobilizations over the past decade, experiencing gains through 2005 but a slight decline since that time.

In March 2007 St. Louis County implemented a seat belt ordinance that allowed for traditional enforcement procedures. In

order to increase usage on St. Louis County roads, particularly

on roadways with fatal or disabling injury crashes, the St. Louis

County Police Department (SLCPD) conducted an intense HVE

campaign along an 8-mile corridor on State Highway 21 (in the

southeastern part of the county). This corridor was selected in

part because there had been at least 8 fatal or disabling injury

crashes along this roadway in recent years. A similar roadway,

Highway 24, was selected in Jackson County (located across the

State) to serve as a comparison site for evaluation purposes.

Media

The HVE program was implemented on November 17, 2008.

A press release was issued three days prior to the start of the

enforcement activity and a media event was held on the first

day of the campaign. The press release and media event were

intendedto generate news stories in the local media.Associated

with the two-week effort, State and County officials reported

10 news stories, evenly distributed among television,radio, and

print media. Nine variable message boards and six permanent

signs were used along the 8-mile corridor to make the public

aware of the ongoing enforcement activity. The variable message boards contained a variety of messages including: “Buckle 

Up – Seatbelt Law Enforced,” “Click It or Ticket,” and “Buckle Up – 

It’s the Law – Ordinance Enforced Ahead.” All six permanent signs

read “Buckle Up. It’s the Law, County Ordinance 1217.095.” There

was no paid media and no public service media.

Enforcement

Enforcement consisted of both saturation patrols and enforcement zones with an emphasis on issuing citations rather than

warnings. The 13-day HVE effort included just over 500 total

enforcement hours. During these hours, all six officers of the

SLCPD Highway Safety Unit plus a small group of additional

officers saturated the targeted corridor, actively observing for

seat belt violations. As a result, they issued a total of 991 citations and 140 warnings for seat belt violations, plus an additional 12 citations for child passenger safety law violations.

Thus, the total number of “actions” or “contacts” for seat belt

and child seat violations was just under 1,150, with 88% of

such actions resulting in citations issued.

Awareness

There were large gains in program awareness and changes in

perceptions for the targeted corridor, Highway 21 in St. Louis

County, whereas few such changes were found for the control corridor, Highway 24 in Jackson County. Awareness of

seat belt enforcement on Highway 21 increased from 17% (preprogram) to 77% (post-program), an increase of 61 percentage

points. Results from the surveys on Highway 24 showed a less

dramatic increase of 9 percentage points in awareness of seat

belt enforcement. The perceived risk of getting a ticket forriding

unbuckled (for six months) increased from 22% to 32% in the

program area. In contrast, there was a small decline in perceived risk for Jackson County.

The percentage of respondents who favored a primary law

increased from 63% to 70% in St. Louis County. In comparison, support for a primary law declined in Jackson

0

10

20

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60

70

80

90

Aware of Police

Efforts to Enforce

17

77

35

44

22

32 36 34

Perceived Risk

of Getting a Ticket

Percent Positive Response

Program (Pre) Program (Post)

Control (Pre) Control (Post)
TRAFFIC TECH is a publication to disseminate information about

traffic safety programs, including evaluations, innovative programs, and new publications. Feel free to copy it as you wish. If you

would like to receive a copy, contact Angela H. Eichelberger, Ph.D.,

Editor, fax 202-366-7394, e-mail: angela.eichelberger@dot.gov.

1200 New Jersey Avenue SE., NTI-132

Washington, DC 20590

County (from 61% to 56%). The percentage of respondents who thought that county police could enforce the seat 

belt law as a primary offense increased from 62% to 69% in

St. Louis County.

Changes in Observed Usage

A total of 25,877 front-seat, passenger-vehicle occupants

were observed along the Highway 21 and 24 corridors.

Observed seat belt use increased by 4.9 percentage points

along the Highway 21 corridor (from 83.3% to 88.2%),

whereas observed use declined by 2.2 percentage points

along the Highway 24 (control) corridor.

Officer and Motorist Reactions

Officers in the Highway Safety Unit reported that the enforcement effort had gone very well and that it became much harder

to find violators towards the end of the campaign. They indicated that most motorists understood why county police were

enforcing the law and supported their efforts. One officer indicated that most of the motorists ticketed did not even know

that the county had a primary ordinance.

Every officerin the unit endorsed the county ordinance wholeheartedly and thought that the State should enact a statewide

primary law. Two indicated that they were now more aware

of the ordinance and were enforcing it more frequently than

before,particularlyas aprimarylaw. Severalindicatedthatthey

thought the fine should be increased from $10 to a minimum of

$25. With regard to how to increase usage or at least maintain a high 

rate in the county, these officers suggested: (a) enacting a statewide primary law; (b) publicizing the law and their efforts; (c)

increasing the fine; and (d) conducting additional enforcement

campaigns. Some additional observations were that: passengers typically did not know that the law applied to them as

well as to drivers; most teens did not know that not wearing

a seat belt was a violation of their restricted driver’s license;

and many motorists were not aware of the county’s primary

ordinance, at least not prior to this campaign.

Summary and Implications

This corridor program was characterized by a strong enforcement effort, with approximately two citations issued per officer

hour worked. Due to a lack of time and resources, there was

no paid media and little or no broadcast media. The results

showed a significant increase in all indices of public awareness

and perception and a significant increase in observed usage in

the targeted corridor. There were significant increases in usage

among pickup truck occupants as well as among occupants of

other vehicles. This is important in that occupants of pickup

trucks have historically had lower observed usage than occupants of other vehicles in Missouri.

If Missouri enacted a statewide primary law upgrade and

implemented regular HVE programs, similar to the program

implemented in St. Louis County, Missouri could experience

an estimated 30 to 70 fewer deaths, 400 to 900 fewer serious

injuries, and $110 million to $215 million in lower economic

costs annually.

How to Order

To order Evaluation of a County Enforcement Program With a 

Primary Seat Belt Ordinance: St. Louis County, Missouri (34 pages),

prepared by Preusser Research Group, write to the Office

of Behavioral Safety Research, NHTSA, NTI-132, 1200 New

Jersey Avenue SE., Washington, DC 20590, fax 202-366-7394,

or download from www.nhtsa.gov or http://ntl.bts.gov/

lib/32000/32900/32972/6804-811292-050710-v1a.pdf.

0

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70

80

Support for Primary

Enforcement

63

70

61

56

62

69

50 51

County Police Can

Enforce as Primary

Percent Positive Response

Program (Pre) Program (Post)

Control (Pre) Control (Post)

0

10

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100

Drivers

83

88

59 57

84

89

48 45

83

88

57 55

Passengers All Occupants

Percent Positive Response

Program (Pre) Program (Post)

Control (Pre) Control (Post)