FEDERAL MOTOR CARRIER SAFETY ADMINISTRATION

FMCSA Contact: Larry Minor, MC-PS, (202) 366-4009

Evaluation of Infrared Brake

Screening Technology

Introduction

The Federal Motor Carrier Safety Administration (FMCSA) sponsored a field study

to evaluate the effectiveness of a technology that uses infrared imaging to screen

commercial motor vehicles (i.e., large trucks and buses) for subsequent inspection.

The technology detects malfunctioning brakes and other problems such as flat

tires. This Tech Brief summarizes the final report, Evaluation of Infrared Brake

Screening Technology: Final Report, which is available from the National

Technical Information Service, and the Department of Transportation's Intelligent

Transportation Systems Electronic Document Library at

www.its.dot.gov/itsweb/welcome.htm.

Background

The Infrared Inspection System (IRISystem) is a minivan equipped with an infrared

camera on the roof and a display screen inside the vehicle. Enforcement

personnel tested its effectiveness at roadside inspection facilities by screening for

brake defects and producing results in a matter of seconds, known as “real time.”

As a commercial motor vehicle decelerates to enter a roadside inspection facility,

an IRISystem operator scans the wheels with the camera. A thermal image of the

wheels, showing their relative temperature, is displayed on the screen inside the

van. Because the application of brakes creates heat, the wheels with functional

(warm) brakes appear bright white in the infrared image, while the wheels with

inoperative (cold) brakes appear dark. A color image enables the operator to

easily identify a vehicle with functional or inoperative brakes.

The goal of the Federal Motor

Carrier Safety Administration

(FMCSA) is to reduce commercial

vehicle related fatalities, as well

as the number of persons injured

in commercial vehicle related

crashes, by 50 percent by the

year 2010. 

FMCSA's Research and

Technology programs encompass

a range of issues and disciplines,

all related to motor carrier and

bus safety and security. FMCSA

defines a “research program” as

any systematic study directed

toward fuller scientific discovery,

knowledge, or understanding

that will improve safety and

security, and reduce the number

and severity of commercial

motor vehicle crashes. Similarly,

a “technology program” includes

those that adopt, develop, test

and/or deploy innovative driver

and/or vehicle best practices, and

technologies that will improve

safety and security, and reduce

the number and severity of

commercial motor vehicle

crashes.

Currently, FMCSA's Office of

Research and Technology

conducts programs in the area of

Driver Safety Performance,

Commercial Vehicle Safety

Performance, Carrier Compliance

and Safety, Safety Systems and

Technology, Cross-Cutting Safety

Initiatives, and Security. The

study described in the following

Tech Brief was designed and

developed as part of FMCSA's

Research and Technology

Commercial Vehicle Safety

Performance Program. The

primary goal of this program is

to improve truck and bus

performance through vehiclebased safety technologies.

Office of Research and Technology

400 Seventh Street, SW

MC-RT, Room 3107

Washington, DC 20590

Tech Brief

Before: Shot of Commercial

Motor Vehicle (CMV) as it enters 

a roadside inspection facility. 

After: Shot of Commercial Motor

Vehicle (CMV) after it has been

scanned by the Infrared Inspection

System (IRISystem). Wheels that

are white indicate that they are

warm/functional. Wheels that are

dark indicate they are

cold/inoperable. 
Purpose

The purpose of the study was to determine the effectiveness of infrared technology in enhancing the

safety screening of commercial motor vehicles in “real time” at the roadside. Researchers evaluated

the IRISystem as a means to: 

• Detect problematic commercial motor vehicle conditions (mainly brake-related defects)

• Improve existing screening methods

Methodology

Four states participated in the yearlong evaluation: Kentucky, Georgia, North Carolina, and

Tennessee. States used the IRISystem at various locations—primarily scale sites on highways—where

commercial motor vehicles could be readily screened and inspected. Operators usually screened

vehicles traveling less than 10 miles per hour (16 kilometers per hour), though experienced operators

assessed vehicles moving up to approximately 40 miles per hour (64 kilometers per hour). At each site

the vehicles were screened by an IRISystem operator and then subjected to a standard Commercial

Vehicle Safety Alliance Level 1 inspection. The inspector was unaware of the results of the IRISystem

screening. 

Approximately 400 vehicles were screened by the IRISystem and subjected to a Level 1 inspection. To

improve the objectivity of the study, 62 vehicles with no apparent problems (according to IRISystem

operators) were selected for Level 1 inspections. These non-problematic vehicles represented 16

percent of the total population of commercial motor vehicles tested. 

Eighty-eight percent of the commercial motor vehicles screened were tractor-trailer combinations.

Operators also inspected bobtail tractors, straight two- and three-axle trucks, and other tractor-trailer

combinations. Approximately 70 percent of the vehicles inspected were loaded. 

The IRISystem results were compared directly with the roadside inspection results. Researchers

conducted both a wheel-by-wheel and a vehicle-by-vehicle comparison. To evaluate the system as a

screening device, researchers then compared the IRISystem results to current screening method results

using SAFETYNET data for the four participating states. SAFETYNET is a state-level information

management system for motor carrier safety. It includes interstate and intrastate driver and vehicle

inspection data, accident data, carrier compliance reviews, enforcement data, and carrier

identification data. 

Results and Implications

Researchers determined that the IRISystem could be used to effectively screen commercial vehicles for

inspection of brake-related problems. Sixty-nine to 76 percent of the wheels identified as

problematic by the IRISystem—whether for malfunctioning brakes, flat tires, under-inflated tires, hot

bearings, or other problems—were confirmed as defective by the Level 1 inspections. Most of these

were brake-related defects.

Kentucky established an effectiveness criterion that 50 percent of the vehicles identified as

problematic by the IRISystem should be confirmed as defective by the Level 1 inspections. All four

states met this criterion. Overall, 59 percent of the vehicles identified as problematic by the IRISystem

were placed out-of-service for brake violations. 

Approximately 10 percent (399 of 3769) of the wheels screened by the IRISystem were identified as

problematic and cold (typically a wheel without braking action). About 1 percent (44 of 3769) were

identified as problematic and hot (usually caused by hot bearings, flat tires, or dragging brakes). The

trailer wheels on the far side (with respect to the IRISystem van) of the commercial motor vehicle

exhibited most of the problems during the screening. Wheel covers on the near-side wheels tended

to obscure the infrared image, whereas the far-side wheels were easier to evaluate because of a

better view of the back of the wheel, and slightly more viewing time as the vehicle passed in front of

the IRISystem van. Researchers found that the presence of brake defects or deficiencies on a

commercial motor vehicle often indicated that other repairs were needed.
Identification of Out-of-Service Commercial Motor Vehicles

Fifty-nine percent (194 of 330) of vehicles identified by the IRISystem as problematic were

subsequently placed out-of-service in the Level 1 inspection. Of these vehicles, 79 percent (153) were

placed out-of-service as a result of brake violations. Twenty-two percent (42) had brake violations

and other out-of-service violations, such as driver-related violations. Of the vehicles initially identified

as non-problematic in the IRISystem screening, 19 percent (12 of 62) were ultimately placed out-ofservice. 

IRISystem As a Screening Device

The results of the evaluation were compared to 1997-1999 SAFETYNET data for the four participating

states. Fifty-nine percent of vehicles were placed out-of-service after IRISystem screening, more than

double the 27 percent placed out-of-service using the current screening methods. The percentage of

vehicles placed out-of-service with brake problems more than doubled after using the IRISystem to

screen vehicles for inspection, from 34 percent with current screening to 84 percent with IRISystem

screening. 

Other Considerations

Training

One-half to one day of training was necessary. Officers with previous IRISystem experience shared

their insight with new trainees. 

Skill Level Requirements

The IRISystem is an operator friendly device and its use is relatively easy to learn. Prior experience

with infrared imaging or the joystick control configuration of the camera helped some operators

collect data more quickly and accurately than less experienced operators. Screening effectiveness

increased with practice.

Owner's Manual

The owner's manual was detailed and included all documentation needed to operate the IRISystem.

However, the manual would benefit from the inclusion of sample IRISystem photographs of

commercial vehicles with typical problems. 

System Set Up and Shutdown

The IRISystem can be set up and shut down with relative ease.

Mainline Screening

Although mainline screening (tests at speeds greater than 55 miles per hour/88.5 kilometers per hour)

was attempted with the IRISystem, no useful results were obtained. Officers indicated that mainline

screening was not practical because of the difficulty in identifying the target vehicle, the inability to

observe all wheels on a commercial motor vehicle traveling at highway speeds, the difficulty of

intercepting the target commercial motor vehicle downstream, and overall safety concerns.

Identification of Non-Brake Related Problems

The IRISystem frequently identified flat tires. Although the system has the capability, no exhaust

leaks, or frame cracks were identified during the testing. 
U.S. Department of Transportation

Researcher

This study was performed by

Battelle Memorial Institute 505

King Avenue, Columbus, OH

43201. Contract No.

DTFH61-96-C-00077.

Distribution

This Tech Brief is distributed

according to a standard

distribution. Direct distribution

is made to the Service Centers

and Divisions.

Availability

The study final report 

DOT-MC-01-007 is available 

from the National Technical

Information Service

(PB2001-100010INZ).

Key Words

brake, brake tester, brake

testing, infrared, screening,

inspection, commercial motor

vehicle

Notice

This Tech Brief is disseminated

under the sponsorship of the

Department of Transportation in

the interest of information

exchange. The Tech Brief

provides a synopsis of the study’s

final publication. The Tech Brief

does not establish policies or

regulations, nor does it imply

USDOT endorsement of the

conclusions or

recommendations. The U.S.

Government assumes no liability

for its contents or their use.

Web Site

All FMCSA Tech and Analysis

Briefs may be accessed at:

www.fmcsa.dot.gov. 

Technical Writer

Craig Steinberg, C2 Technologies, Inc.

July 2002

Publication No. FMCSA-MCRT-02-100

Federal Highway Administration

Location and Speed

The IRISystem is a mobile device and can be used at various scale sites and other

suitable inspection locations. To achieve effective use, the IRISystem should be

placed at sites where commercial motor vehicles must apply their brakes to enter.

Vehicles are typically screened at speeds less than 10 miles per hour (16

kilometers per hour), although experienced and skilled operators can screen

vehicles moving up to about 40 miles per hour (64 kilometers per hour). It is

recommended that the IRISystem van be set up with the center of the camera

range roughly perpendicular to the direction of the traffic flow, so the operator

can track vehicles easily and with an unobstructed view of the wheels. 

Temperature

The use of the IRISystem is not dependent upon outside temperature or day/night

conditions.

Funding/Eligibility

FMCSA has approved the IRISystem as an eligible expense under the Motor

Carrier Safety Assistance Program, which enables states to use Federal funds

toward the purchase of the technology. 

References

Christiaen, Anne-Claire; and Steve J. Shaffer. Evaluation of Infrared Brake

Screening Technology: Final Report, FMCSA, Publication No. DOT-MC-01-007, NTIS

No. PB2001-100010INZ, Washington, DC, December 2000.