Number 333 August 2007

Traffic Safety Facts

Traffic Tech – Technology Transfer Series

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

National Highway Traffic Safety Administration

Automated Speed Enforcement (ASE) combines speed

measurement and imaging of speeding vehicles to provide for automatic ticketing of vehicles exceeding a

preset threshold. ASE has the potential to deter speeding over a specific location if drivers are aware of the 

presence of ASE systems. Many communities that have

used ASE report a reduction in speeds, and some have

reported a reduction in crashes following implementation of ASE programs (e.g., Cunningham, Hummer, &

Moon, 2005; Retting & Farmer, 2003; Cities of Beaverton & Portland, 1997; Elvik, 1997).

Since 1995, 170 school-age pedestrians (younger than

19) have died in school-transportation-related crashes.

While 70 percent of these children were killed by school 

buses (or by vehicles functioning as school buses), 30

percent were killed by other vehicles involved in the 

crashes. Due to their lower awareness of risk and impulsive behavior, child pedestrians are particularly vulnerable. Nearly half of all school-age pedestrians killed in

school transportation-related crashes were age 5 to 7. 

ASE technology provides a highly visible speed enforcement presence with minimal disruption of traffic 

flow, and is well suited to speed enforcement in school 

zones. NHTSA contracted with Westat, Inc., to conduct 

a demonstration of ASE in school zones in Portland, Oregon, and to evaluate the program’s effects on reducing

traffic speeds along with the public attitudes and perceptions toward ASE. 

Method

ASE was deployed two to three times per week at five 

school zones in Portland, Oregon, during a three-month

period from March through May 2005. Five additional

school zones, located in north, northeast, and southwest 

Portland, served as comparison sites without ASE. 

In Portland, school zones have a 20 mph speed limit 

24 hours a day. All of the demonstration school zones

(and four of the comparison schools) also had flashing beacons, activated during school hours, signifying

higher fines for speeding. 

The Portland Police Bureau Traffic Division, using two 

ASE unit vans, deployed ASE two to three times per 

week at each of the five demonstration school zones. 

ASE was in place for a total of 331 hours across all sites.

To maximize deterrence, a publicity campaign including a press conference that attracted citywide media attention was held prior to the deployment of ASE. The 

campaign targeted the neighborhoods of the five demonstration school zones. Road signs were also installed 

stating“PhotoEnforced”tosupplementexisting“School

Speed 20” signs in the demonstration school zones.

Public perceptions and awareness of the ASE program 

were surveyed on a sample of 400 residents both prior 

to and during the demonstration program. Traffic volume and speeds were measured by means of JAMAR 

TRAX RD pneumatic road tube traffic counters for at 

least 24 hours prior to, during, and following the ASE 

deployment program.

Findings

When ASE was present and the flashing beacon was off, 

85th percentile speeds at demonstration school zones

were reduced by approximately 5 mph compared to 

before the ASE demonstration. Eighty-fifth percentile 

speeds decreased from 32.4 mph to 27.8 mph. When

ASE was present and the flashing beacon was on, 85th 

percentile speeds were approximately 8-9 mph lower 

in the demonstration zones than when neither ASE nor 

the beacon was present (see Figure 1).

Automated Speed Enforcement in School Zones 

in Portland, Oregon
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 Patricia Ellison-Potter, Ph.D., 

Editor, fax 202-366-7096, e-mail: traffic.tech@dot.gov.

Figure 1. 85th Percentile Speeds for Demonstration Sites 

by Beacon and Test Condition

Figure 2 shows the data for comparison sites. In the 

comparison school zones, no difference in speeds

was observed between the pre-demonstration period, 

demonstration period, and post-demonstration period

when the flashing beacon was on. A small decrease in 

the 85th percentile speeds of 0.6 mph was observed 

from the pre-demonstration to post-demonstration

with the beacon off, similar to the decrease of 0.8 mph 

at the demonstration school zones.

One notable finding was that speed reduction effects 

achieved at the demonstration school zones lasted for

at least a full month after ASE ceased.

Implications

ASE can be used to reduce speeds in school zones. ASE

was shown to be most effective in this application when 

combined with a flashing beacon. 

How to Order

For a copy of Automated Speed Enforcement in School 

Zones in Portland, Oregon (45 pages plus appendices),

prepared by Westat, write to the Office of Behavioral 

Safety Research, NHTSA, NTI-130, 1200 New Jersey 

Avenue SE., Washington, DC 20590, send a fax to 202-

366-7096, or download from www.nhtsa.dot.gov. Paul

J. Tremont, Ph.D., was the project officer.

1200 New Jersey Avenue SE., NTI-130

Washington, DC 20590

24

25

26

27

28

29

30

31

32

Speed (mph)

Comparison Sites

Beacon Off

Comparison Sites

Beacon On

Beacon Condition

31.2

27.0

30.8

27.0

30.6

27.0

Predemonstration

During - WO ASE

Post

Figure 2. Percentile Speeds for Comparison Sites by 

Beacon & Test Condition

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

Speed (mph)

Demonstration Sites

Beacon Off

Demonstration Sites

Beacon On

Beacon Condition

32.4

29.8 31.6

27.8 27.6

31.6

23.4

28.0

Predemonstration

During - WO ASE

During With ASE

Post