Traffic Safety Facts 

Traffic Tech – Technology Transfer Series 

Number 388	 April 2010

Nighttime Enforcement of Seat Belt Laws: 

An Evaluation of Three Community Programs 

Background 

Enforcement of seat belt laws has been conducted largely 

during daylight hours. Daytime enforcement programs 

have worked well to improve observed belt use rates during 

the day, but have been shown less often to affect nighttime 

use. Fatality data show that unbelted occupants at night are 

a large portion of the motor vehicle fatality problem, with 

belt use at its lowest around 1 a.m. A substantial reduction in 

fatalities could be achieved by getting late-night occupants 

to buckle up. 

This study had two objectives. The first objective was to collect information regarding methods of nighttime enforcement. The second objective was to implement and evaluate 

programs that enforced the seat belt use law at night. 

Methods of Nighttime Enforcement 

Discussions were conducted with law enforcement agencies 

(LEAs) to better understand current or planned approaches 

to night belt enforcement and determine prerequisites to 

those approaches. From these discussions, four general techniques were identified with sub-types: 

1.	 Checkpoints/Safety Zones/Mini-Cades: 

Seat Belt Checkpoint—This is a set point somewhere 

on a roadway where highly visible law enforcement 

officers with marked vehicles check motorists for seat belt 

violations. 

Combined Alcohol/Belt Checkpoint—A seat belt checkpoint and a sobriety checkpoint are implemented at the 

same time. 

Safety Enforcement Zone—Like a checkpoint operation 

but with signage indicating a “safety enforcement zone” 

is ahead. 

Mini-Cade—This tactic requires as few as three officers 

who put up signs stating that a “seat belt check” or “safety 

check” is ahead. Patrol car lights are left on for attention. 

Moving violations are not necessarily ticketed due to a 

relatively low number of officers on the scene. A warning 

and safety literature is often provided to passing motorists 

who are not complying. 

2.	 Unsigned Enforcement Spotters—A plain clothes or uniformed officer stands well ahead of other enforcement 

officers and spots violations. This enforcement tactic is 

judged to be the most productive for issuing seat belt tickets when done in a primary law environment. 

3.	 Saturation Patrols—This tactic includes putting more 

patrol vehicles than usual in a designated area and asking officers to spot and stop motorists not complying with 

the seat belt law. It can lack mobility at night because it is 

limited to lighted locations. This approach is very difficult 

in secondary law locations. 

4.	 Routine Patrol—Officers are asked to spot and enforce 

seat belt violations during their normal traffic patrol activities. This technique lacks mobility because it is limited to 

lighted locations. This approach is very difficult in secondary law locations. 

Evaluation of Nighttime Enforcement Methods 

Three study communities participated in high-visibility 

enforcement (HVE) demonstration programs designed to 

improve nighttime seat belt use: Asheville and Greenville, 

North Carolina, and Charleston, West Virginia. The HVE 

programs consisted of four 10-day periods of nighttime traffic enforcement during each quarter of calendar year 2007. At 

a minimum, the belt enforcement occurred between 10 p.m. 

and 2 a.m. Enforcement efforts were supported with paid and 

earned media that focused on nighttime belt enforcement. 

Program evaluation included collection of enforcement and 

media data, program awareness surveys, and observation 

surveys of seat belt use at night. Breath tests at roadside to 

obtain blood alcohol concentration (BAC) measures, and 

analysis of data on single-vehicle nighttime crashes, were 

used in Asheville to determine whether the night belt program affected drinking and driving. 

Asheville implemented seat belt checkpoints in a State containing primary enforcement provisions. Greenville chose 

U.S. Department of Transportation 1200 New Jersey Avenue SE., Washington, DC 20590 

National Highway Traffic Safety Administration 
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

saturation patrols as its intervention approach. Charleston, 

working with a law containing secondary enforcement provisions, used safety enforcement zones. Table 1 describes 

the enforcement effort at each site. Personnel hours differed 

between the test communities, and enforcement hours varied across waves. Nonetheless, all three test sites had a large 

enforcement presence in each wave. The type of enforcement 

clearly affected the number of seat belt tickets issued; officers 

in Asheville and Charleston wrote far fewer seat belt citations 

compared to Greenville. Belt enforcement at night also led to 

DUI arrests, speeding tickets, and other citations.

Table 3: Asheville Drivers With Positive BACs

Wave

Pre

Po

Diff

BAC > .00 BAC > .049 BAC > .079

 1

st

.

16%

11%

-5a

6%

4%

-2

2%

3%

+1

Wave 3

Pre

Post

Diff.

14%

14%

0

4%

3%

-1

2%

2%

0

Wave 4

Pre

Post

Diff.

14%

10%

-4a

3%

3%

0

2%

1%

-1

a

Chi-square Test; Statistically Significant at p<.05

includes the drivers in the column and columns to the right). 

The Wave 3 post-test doubled as the Wave 4 pre-test because 

the close proximity of the two enforcement waves to each 

other did not allow sufficient time to conduct two BAC data 

collection waves. Table 3 shows the percentage of drinking 

drivers decreasing over the course of the program. Crash 

data analysis showed the number of single vehicle nighttime 

crashes appearing to decrease during the one month following each program wave. This suggested that the Asheville 

night belt program also deterred alcohol-impaired driving. 

Table 1: Enforcement Efforts

Wave 1 Wave 2* Wave 3 Wave 4

Asheville:

Program Checkpoints 10 10 13 15

Personnel Hours 518 720 592 406

Seat Belt Tickets 32 20 60 35

DUI Arrests 21 31 17 8

Speeding 9 9 40 77

Other Tickets/Arrests 283 396 364 161

Greenville:

Spotter/Saturation Patrols 35 34 35 36

Personnel Hours 536 536 329 370

Seat Belt Tickets 421 301 223 149

DUI Arrests 25 18 17 16

Speeding 51 11 25 44

Other Tickets/Arrests 222 210 198 166

Charleston:

Traffic Safety Zones 17 10 10 9

Personnel Hours 739 1009 1041 640

Seat Belt Tickets 40 32 31 27

DUI Arrests 26 34 36 17

Speeding 24 74 150 225

Other Tickets/Arrests 229 461 250 78

*Coincided with National Click It or Ticket Campaign

Table 2: Observed Nighttime Belt Use Rate

a

Chi-s

b

Chi-s

1

Binar

2

Binar

Asheville

Raw/Weighted

Greenville

Raw/Weighted

Charleston

Raw/Weighted

Wave 1

Pre

Post

Diff.

83.3% 85.6%

85.5% 87.5%

+2.2b +1.92

86.1% 83.4%

85.8% 84.6%

-0.3 +1.2

58.4% 58.4%

66.7% 61.8%

+8.3a

 +3.42

Wave 3

Pre

Post

Diff.

85.9% 86.3%

89.3% 89.5%

+3.4a

 +3.21

86.3% 86.2%

88.5% 87.6%

+2.2a

 +1.4

70.2% 66.1%

71.4% 70.2%

+1.2 +4.11

Wave 4

Pre

Post

Diff.

83.7% 83.4%

91.0% 92.5%

+7.3a

 +9.11

87.2% 86.8%

87.3% 87.1%

+0.1 +0.3

63.2% 64.5%

66.5% 60.2%

+3.3b

 -4.31

quare Test; Statistically Significant at p<.01

quare Test; Statistically Significant at p<.05

y Logistic Regression; Statistically Significant at p<.01

y Logistic Regression; Statistically Significant at p<.05

Table 2 shows the observed nighttime belt use rate before 

and after the enforcement intervention for three of the four 

enforcement waves. No observations were conducted surrounding Wave 2, which coincided with the national Click It or 

Ticket mobilization. Nighttime belt use increased in Asheville 

and Charleston using checkpoint style enforcement. Greenville, which issued the greatest number of seat belt tickets 

through saturation patrols, had less improvement. While 

Charleston showed a decrease in observed belt use during 

Wave 4 according to weighted numbers, this was attributed 

to a handful of observation sites with relatively few observations collected at night. Examination of raw data showed a 

contrasting increase.

Voluntary breath tests were conducted at Asheville checkpoints. Table 3 shows the percentage of tested drivers found 

to be above each of three specified BAC levels (each column 

How to Order

For a copy of Nighttime Enforcement of Seat Belt Laws: An 

 Evaluation of Three Community Programs (37 pages plus 

 appendices) prepared by Preusser Research Group, Inc., 

write to the Office of Behavioral Safety Research, NHTSA, 

NTI-130, 1200 New Jersey Avenue SE., Washington, DC 

20590, or send a fax to 202-366-7394, or download from 

www.nhtsa.gov.