9478 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

1 49 CFR 571.111, Standard No. 111, Rearview 

Mirrors. 

2We note that this is different than what many 

people informally call a ‘‘blind spot,’’ a term used 

to describe an area to the side of the car where 

people may not be able to see a vehicle when 

changing lanes. 

DEPARTMENT OF TRANSPORTATION 

National Highway Traffic Safety 

Administration 

49 CFR Part 571 

[Docket No. NHTSA–2009–0041] 

RIN 2127–AK43 

Federal Motor Vehicle Safety Standard; 

Rearview Mirrors 

AGENCY: National Highway Traffic 

Safety Administration (NHTSA), 

Department of Transportation (DOT). 

ACTION: Advance notice of proposed 

rulemaking (ANPRM). 

SUMMARY: This document initiates 

rulemaking to amend Federal Motor 

Vehicle Safety Standard (FMVSS) No. 

111, Rearview Mirrors,1 to improve a 

driver’s ability to see areas to the rear 

of a motor vehicle in order to mitigate 

fatalities and injuries associated with 

backover incidents. The agency and 

Congress are concerned that vehicles 

have ‘‘blind zones,’’ 2 areas behind the 

vehicle in which drivers may have 

difficulty seeing and avoiding a person 

or other obstacle. Through this notice, 

NHTSA presents its initial research 

efforts and solicits additional 

information that will enable the agency 

to develop an effective proposal to 

mitigate backover incidents related to 

vehicle rear blind zones. 

DATES: Comments must be received on 

or before May 4, 2009. 

ADDRESSES: You may submit comments 

to the docket number identified in the 

heading of this document by any of the 

following methods: 

• Federal eRulemaking Portal: Go to 

http://www.regulations.gov. Follow the 

online instructions for submitting 

comments. 

• Mail: Docket Management Facility: 

U.S. Department of Transportation, 1200 

New Jersey Avenue, SE., West Building 

Ground Floor, Room W12–140, 

Washington, DC 20590–0001. 

• Hand Delivery or Courier: 1200 

New Jersey Avenue, SE., West Building 

Ground Floor, Room W12–140, between 

9 a.m. and 5 p.m. ET, Monday through 

Friday, except Federal holidays. 

• Fax: 202–493–2251 

Instructions: For detailed instructions 

on submitting comments and additional 

information on the rulemaking process, 

see the Public Participation heading of 

the SUPPLEMENTARY INFORMATION section 

of this document. Note that all 

comments received will be posted 

without change to http:// 

www.regulations.gov, including any 

personal information provided. Please 

see the Privacy Act heading below. 

Privacy Act: Anyone is able to search 

the electronic form of all comments 

received into any of our dockets by the 

name of the individual submitting the 

comment (or signing the comment, if 

submitted on behalf of an association, 

business, labor union, etc.). You may 

review DOT’s complete Privacy Act 

Statement in the Federal Register 

published on April 11, 2000 (65 FR 

19477–78) or you may visit http:// 

DocketInfo.dot.gov. 

Docket: For access to the docket to 

read background documents or 

comments received, go to http:// 

www.regulations.gov or the street 

address listed above. Follow the online 

instructions for accessing the dockets. 

FOR FURTHER INFORMATION: For technical 

issues: Ms. Elizabeth Mazzae, Vehicle 

Research and Test Center, Telephone: 

(937) 666–4511. Facsimile: (202) 366– 

3171. For legal issues: Ari Scott, Office 

of Chief Counsel, Telephone (202) 366– 

2992. Facsimile: (202) 366–3820. You 

may send mail to these officials at: The 

National Highway Traffic Safety 

Administration, Attention: NVS–010, 

1200 New Jersey Avenue, SE., 

Washington, DC 20590. 

SUPPLEMENTARY INFORMATION: 

I. Executive Summary 

II. Cameron Gulbransen Kids Transportation 

Safety Act of 2007 

III. Existing Regulatory Requirements for Rear 

Visibility 

A. U.S. 

B. Other Countries 

IV. Backover Safety Problem 

A. Injuries and Fatalities in Backing 

Incidents 

B. Vehicle Type Involvement in Backing 

Incidents 

C. Age Involvement in Backing Incidents 

D. SCI Backover Case Summary 

E. Assessment of Backover Crash Risk by 

Pedestrian Location 

V. Technologies for Improving Rear Visibility 

A. Rear-Mounted Convex Mirrors 

B. Rearview Video Systems 

C. Sensor-Based Rear Object Detection 

Systems 

D. Multi-Technology (Sensor + Video 

Camera) Systems 

E. Future Technologies 

F. Summary and Questions Regarding 

Technologies for Improving Rear 

Visibility 

VI. Drivers’ Use and Associated Effectiveness 

of Available Technologies to Mitigate 

Backovers 

A. Rear-Mounted Convex Mirrors 

B. Rearview Video Systems 

C. Sensor-Based Rear Object Detection 

Systems 

D. Multi-technology (Sensor + Camera) 

Systems 

E. Summary 

F. Questions 

VII. Rear Visibility of Current Vehicles 

VIII. Relationship Between Rear Visibility 

and Backing/Backover Crashes 

IX. Options for Mitigating Backover Incidents 

A. Approaches for Improving Vehicles’ 

Rear Visibility 

B. Cost Benefit Scenarios 

C. Questions 

X. Options for Measuring a Vehicle’s Rear 

Visibility 

A. Rear Visibility Measurement Procedures 

B. Rear Visibility Measurement Method 

Variability 

C. Comparison of Human-Based Versus 

Laser-Based Rear Visibility Measurement 

Protocols 

D. Input From Industry Regarding Rear 

Visibility Measurement 

E. Questions 

XI. Options for Assessing the Performance of 

Rear Visibility Countermeasures 

A. Countermeasure Performance Test 

Object 

B. Countermeasure Performance Test Area 

C. Countermeasure Performance Test 

Procedure 

D. Questions 

XII. Options for Characterizing Rear Visibility 

Countermeasures 

A. Options for Display Characteristics 

B. Options for Rearview Video System 

Camera Characteristics 

C. Questions 

XIII. Conclusion 

XIV. Public Participation 

XV. Rulemaking Analyses and Notices 

Appendix A—Methodology for Assessing 

Backover Crash Risk by Pedestrian 

Location 

Appendix B—Method for On-Road Study of 

Drivers’ Use of Rearview Video Systems 

Appendix C—Details Regarding Development 

of a Possible Countermeasure 

Application Threshold Based on Rear 

Blind Zone Area 

Appendix D—Results for Analysis of 

Correlation Between Rear Blind Zone 

Area Measurement Field Size and 

Backing Crashes 

I. Executive Summary 

This advance notice of proposed 

rulemaking (ANPRM) initiates 

rulemaking to amend Federal Motor 

Vehicle Safety Standard (FMVSS) No. 

111, Rearview Mirrors, to improve a 

driver’s ability to see areas to the rear 

of a motor vehicle to reduce backover 

incidents. The agency is issuing an 

ANPRM for two reasons. First, the 

agency is obligated, pursuant to the 

Cameron Gulbransen Kids 

Transportation Safety Act of 2007 (the 

‘‘K.T. Safety Act’’) Public Law 110–189, 

February 28, 2008, 122 Stat. 639, to 

undertake rulemaking to expand the 

required field of view to enable the 

driver of a motor vehicle to detect areas 

Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9479 

3We note that this is different than what many 

informally call a ‘‘blind spot,’’ a term used to 

describe an area to the side of the car where people 

may not be able to see a vehicle when changing 

lanes. 

4Safe, Accountable, Flexible, Efficient 

Transportation Equity Act: A Legacy for Users 

(SAFETEA–LU), Public Law No. 109–59, section 

1109, 119 Stat. 1114, 1168 (2005). 

5Fatalities and Injuries in Motor Vehicle Backing 

Crashes, NHTSA Report to Congress (2008). 

6Partyka, S., Direct-View Rear Visibility and 

Backing Risk for Light Passenger Vehicles (2008). 

7PRIA, Executive Summary. 

8 $6.1 million is the comprehensive value that 

NHTSA used for a statistical life. Further 

information about this value is available in the 

PRIA published with this notice. 

behind the vehicle to reduce death and 

injury resulting from backing incidents 

and initiate the rulemaking in a 

specified time period. Second, as there 

are a wide variety of means to address 

the problem of backover incidents, the 

National Highway Traffic Safety 

Administration (NHTSA) is interested 

in soliciting public comment on the 

current state of research and the efficacy 

of available countermeasures. 

The problem of backovers claims the 

lives of approximately 292 people, 

many of them children every year. A 

backover is a specifically-defined type 

of incident, in which a non-occupant of 

a vehicle (i.e., a pedestrian or cyclist) is 

struck by a vehicle moving in reverse. 

Unlike most other types of crashes, 

many backovers occur off public 

roadways, in areas such as driveways 

and parking lots. Furthermore, a 

disproportionate number of victims of 

backovers are children under 5 years old 

and adults 70 or older. While there are 

several potential reasons for this, 

children are particularly likely to be 

missed by drivers of rear-moving 

vehicles because they cannot be seen 

due to a ‘‘blind zone’’ 3 in the area 

directly to the rear of vehicle. In 

addition, children are more likely to 

move unknowingly into a blind zone 

when the driver does not suspect 

anyone to be there. 

NHTSA believes that the problem of 

backovers warrants an appropriate 

agency action. In response to a 

Congressional requirement of the Safe, 

Accountable, Flexible, Efficient 

Transportation Equity Act: A Legacy for 

Users (SAFETEA–LU) 4, NHTSA has 

been gathering data on backover 

incidents from a wide variety of sources. 

Based on this research, the agency 

estimates that on average there are 292 

fatalities and 18,000 injuries (3,000 of 

which are judged to be incapacitating) 

resulting from backovers every year. Of 

those, 228 fatalities and 17,000 injuries 

were attributed to backover incidents 

involving passenger vehicles under 

10,000 pounds. While all passenger 

vehicle types (cars, sport utility 

vehicles, pickups, and vans) are 

involved in backover fatalities and 

injuries, the data indicate that backover 

fatality numbers show pickup trucks (72 

of 288) and utility vehicles (68 of 228) 

to be overrepresented when compared 

to all non-backing traffic injury crashes 

and to their proportion to the passenger 

vehicle fleet. Regardless of the type of 

vehicle involved, backover incidents 

have garnered significant attention, due 

to the fact that many have involved 

parents accidentally backing over their 

own children or similar situations. In 

this notice, NHTSA describes some of 

the research and information-gathering 

activities it has performed. This 

research centers on four major topic 

areas. 

The first area involves the nature of 

backover incidents and backing crashes 

generally. NHTSA has reviewed the 

details of documented backover 

incidents, including the locations of 

backover victims, the paths the victims 

took to enter the path of the vehicle, and 

the visibility characteristics of the 

vehicles involved. This notice outlines 

the information we have about these 

crashes, whether the lack of visibility is 

playing a significant role, and whether 

or not the characteristics of a class or 

type of vehicle are a contributing factor. 

A second area of focus involves the 

evaluation of various strategies for 

improving rear visibility. For example, 

one strategy could be to ensure that the 

vehicles which are over represented in 

terms of fatalities and injuries are 

improved. Such a strategy would focus 

on pickup trucks or utility vehicles.5

Another strategy, could seek to establish 

a minimum blind zone area for vehicles 

under 10,000 pounds. Our research 

indicates that a vehicle’s rear blind zone 

area is statistically correlated with its 

rate of backing crashes.6 Using this 

correlation, it may be possible to 

determine which vehicles most warrant 

rear visibility improvement based on the 

size of their rear blind zones and the 

setting of a ‘‘threshold’’. Possible 

strategies such as these are discussed in 

this notice and comments are requested. 

The third topic involves the 

evaluation of various countermeasures. 

NHTSA has consulted past agency 

research, industry and other outside 

sources, and conducted new research to 

help determine the costs, effectiveness, 

and limitations of a wide variety of 

countermeasures. Four types of 

countermeasures are described in this 

notice, including direct vision (i.e., 

what can be seen by a driver glancing 

directly out a vehicle’s windows), rearmounted convex mirrors, rear object 

detection sensors (such as ultrasonic or 

radar-based devices), and rearview 

video (RV) systems. While research is 

ongoing, this notice describes how these 

systems work, how well they perform in 

identifying pedestrians, and how 

effectively drivers may use them. Where 

possible, we have also included 

preliminary cost and benefit 

information. While we examine several 

application scenarios (all passenger cars 

and all light trucks, only light trucks, 

and some combinations) and discount 

rates of 3 and 7 percent, the net cost per 

equivalent life saved for camera systems 

ranged from $13.8 to $72.2 million.7 For 

sensors, it ranged from $11.3 to $62.5 

million. According to our present 

model, none of the systems are cost 

effective compared to our 

comprehensive cost estimate for a 

statistical life of $6.1 million.8

A fourth topic involves consideration 

of technical specifications and test 

procedures that could be used to 

describe and evaluate the performance 

aspects of direct view, and rearmounted convex mirrors, rear object 

detection sensors, and rearview video 

(RV) systems. The agency presents 

preliminary information on potential 

technical specifications and test 

procedures that we have identified and 

we want to solicit information on how 

these specifications and procedures 

should be refined for the purposes of 

developing repeatable compliance tests. 

Finally, NHTSA presents a series of 

questions in this notice. We are 

requesting public input on a variety of 

areas, including the areas described 

above, studies on the effectiveness of 

various indirect rear visibility systems 

(i.e., devices that aid a driver in seeing 

areas around a vehicle, such as mirrors 

or video systems) that have been 

implemented in the U.S. and abroad, or 

technological possibilities that can 

enhance the reliability of existing 

technologies. The agency is also seeking 

information on the costs of 

implementation of all available 

technologies to develop more robust 

cost and benefit estimates. 

II. Cameron Gulbransen Kids 

Transportation Safety Act of 2007 

Subsection (b) of the Cameron 

Gulbransen Kids Transportation Safety 

Act, directs the Secretary of 

Transportation to initiate rulemaking to 

amend Federal Motor Vehicle Safety 

Standard (FMVSS) No. 111, Rearview 

Mirrors, to expand the required field of 

view to enable the driver of a motor 

vehicle to detect areas behind the motor 

9480 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

9Cameron Gulbransen Kids Transportation Safety 

Act of 2007, S.694, 110th Cong. section 4 (2007). 10 49 CFR 571.111, Standard No. 111, Rearview 

mirrors. 11See Federalism discussion below in section XV. 

vehicle to reduce death and injury 

resulting from backing incidents. 

The relevant provisions in subsection 

(b) are as follows: 

(b) Rearward Visibility—Not later than 12 

months after the date of the enactment of this 

Act, the Secretary shall initiate a rulemaking 

to revise Federal Motor Vehicle Safety 

Standard 111 (FMVSS 111) to expand the 

required field of view to enable the driver of 

a motor vehicle to detect areas behind the 

motor vehicle to reduce death and injury 

resulting from backing incidents, particularly 

incidents involving small children and 

disabled persons. The Secretary may 

prescribe different requirements for different 

types of motor vehicles to expand the 

required field of view to enable the driver of 

a motor vehicle to detect areas behind the 

motor vehicle to reduce death and injury 

resulting from backing incidents, particularly 

incidents involving small children and 

disabled persons. Such standard may be met 

by the provision of additional mirrors, 

sensors, cameras, or other technology to 

expand the driver’s field of view. The 

Secretary shall prescribe final standards 

pursuant to this subsection not later than 36 

months after the date of enactment of this 

Act. 

(c) Phase-In Period— 

(1) PHASE-IN PERIOD REQUIRED—The 

safety standards prescribed pursuant to 

subsections (a) and (b) shall establish a 

phase-in period for compliance, as 

determined by the Secretary, and require full 

compliance with the safety standards not 

later than 48 months after the date on which 

the final rule is issued. 

(2) PHASE-IN PRIORITIES—In establishing 

the phase-in period of the rearward visibility 

safety standards required under subsection 

(b), the Secretary shall consider whether to 

require the phase-in according to different 

types of motor vehicles based on data 

demonstrating the frequency by which 

various types of motor vehicles have been 

involved in backing incidents resulting in 

injury or death. If the Secretary determines 

that any type of motor vehicle should be 

given priority, the Secretary shall issue 

regulations that specify— 

(A) which type or types of motor vehicles 

shall be phased-in first; and 

(B) the percentages by which such motor 

vehicles shall be phased-in. 

Congress emphasized the protection 

of small children and disabled persons, 

and added that the revised standard 

may be met by the ‘‘provision of 

additional mirrors, sensors, cameras, or 

other technology to expand the driver’s 

field of view.’’ While NHTSA does not 

interpret the Congressional language to 

necessarily require that all of these 

technologies eventually be integrated 

into the final requirement, we are 

examining the merits of each of them. 

Applicability 

With regard to the scope of vehicles 

covered by the mandate, the statute 

refers to all motor vehicles less than 

10,000 pounds (except motorcycles and 

trailers). This language means that the 

revised regulation would apply to 

passenger cars, multipurpose passenger 

vehicles, buses, and trucks with a Gross 

Vehicle Weight Rating (GVWR) less than 

10,000 lbs. 

Statutory Deadline 

The Cameron Gulbransen Kids 

Transportation Safety Act of 2007 

specified a rapid timeline for 

development and implementation of 

this rulemaking. Specifically, the 

Secretary is required to publish a final 

rule within 36 months of the passage of 

the Act (February 28, 2011). Moreover, 

the agency must initiate rulemaking 

within 12 months of the Act (February 

28, 2009). However, it should be noted 

that under Section 4 of the Act,9 if the 

Secretary determines that the deadlines 

applicable under this Act cannot be met, 

the Secretary shall establish new 

deadlines, and notify the Committee on 

Energy and Commerce of the House of 

Representatives and the Committee on 

Commerce, Science, and Transportation 

of the Senate of the new deadlines 

describing the reasons the deadlines 

specified under the Act could not be 

met. 

III. Existing Regulatory Requirements 

for Rear Visibility 

As of today, no country has minimum 

rear field of view requirements for 

vehicles weighing less than 10,000 lbs. 

All countries do, however, have 

standards for side and interior rearview 

mirrors, although differences do exist in 

terms of mirror requirements. No 

country requires rearview video systems 

or any other type of indirect vision 

device for viewing areas directly behind 

the vehicle; however, Europe does have 

performance requirements for systems 

for indirect vision, if installed. 

A. U.S. 

FMVSS No. 111, Rearview Mirrors 

establishes requirements for the use, 

field of view, and mounting of motor 

vehicle rearview mirrors for rear 

visibility.10 This standard was enacted 

in 1976 and applies to passenger cars, 

multipurpose passenger vehicles, 

trucks, buses, school buses and 

motorcycles. The purpose of this 

standard is to reduce the number of 

deaths and injuries that occur when the 

driver of a motor vehicle does not have 

a clear and reasonably unobstructed 

view to the rear. With respect to 

passenger cars, the standard requires 

that manufacturers mount flat (also 

referred to as ‘‘plane’’ or ‘‘unit 

magnification’’) mirrors both inside the 

vehicle and outside the vehicle on the 

driver’s side. The inside mirror must, 

except as specified below, have a field 

of view at least 20 degrees wide and a 

sufficient vertical angle to provide a 

view of a level road surface extending 

to the horizon beginning not more than 

200 feet (61 m) behind the vehicle. In 

cases where the interior mirror does not 

meet the specified field of view 

requirements, a plane or convex exterior 

mirror must be mounted on the 

passenger’s side of the car. While a 

specific field of view is not indicated for 

the passenger-side rearview mirror, the 

driver’s side rearview mirror is required 

to be a plane mirror that provides ‘‘the 

driver a view of a level road surface 

extending to the horizon from a line, 

perpendicular to a longitudinal plane 

tangent to the driver’s side of the 

vehicle at the widest point, extending 

2.4 m (7.9 ft) out from the tangent plane 

10.7 m (35.1 ft) behind the driver’s eyes, 

with the seat in the rearmost position.’’ 

If a manufacturer uses an interior 

rearview mirror which meets the field of 

view requirements, and wishes to install 

an exterior passenger-side mirror 

voluntarily, it may use any type of 

mirror for that purpose. In the case of 

light trucks, manufacturers may either 

comply with the passenger car 

requirement or have plane or convex 

outside mirrors with reflective surface 

area of not less than 126 square 

centimeters (19.5 square inches) on each 

side of the vehicle. Reflectance (image 

brightness) criteria are also established 

in this standard. 

FMVSS No. 111 does not currently 

establish minimum rear field of view 

requirements for vehicles, nor does it 

contain minimum requirements for 

indirect vision systems, such as 

rearview video systems. Because of the 

current absence of a federal regulation 

of this aspect of performance, there is 

the possibility that there may be existing 

State laws or regulations that regulate 

the vehicle’s rear field of view of 

passenger vehicles.11 However, as of 

this time, NHTSA is not aware of any 

such State laws or regulations. However, 

we request comment on existing or 

pending State laws or regulations in this 

area, as well as the basis and effect of 

such regulation, if any exist. 

B. Other Countries 

ECE 

In 1981, the United Nations Economic 

Commission for Europe (ECE) enacted 

Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9481 

12ECE 46–02, Uniform Provisions Concerning the 

Approval of: Devices for Indirect Vision and of 

Motor Vehicles with Regard to the Installation of 

these Devices, (August 7, 2008). 

13 ISO 15008:2003 Road vehicles—Ergonomic 

aspects of transport information and control 

systems—Specifications and compliance 

procedures for in-vehicle visual presentation. 

14Section 15.3.5 of ECE 46–02, Uniform 

Provisions Concerning the Approval of: Devices for 

Indirect Vision and of Motor Vehicles with Regard 

to the Installation of these Devices, (August 7, 

2008). 

15 Japanese Safety Regulation Article 44 and 

attachments 79–81. 

16 Vehicles manufactured for the Japanese market 

are right-hand drive. 17 Korean Safety Regulation Article 50. 

Regulation 46 which details uniform 

provisions concerning the approval of 

devices for indirect vision.12 ECE 46 

defines devices for indirect vision as 

those that observe the area adjacent to 

the vehicle which cannot be observed 

by direct vision, including 

‘‘conventional mirrors, camera-monitors 

or other devices able to present 

information about the indirect field of 

vision to the driver.’’ While ECE 46 

contains specifications for exterior 

rearview mirrors, it does not, directly 

regulate the rear field of view. 

Specifications are provided to define the 

required minimum size of the interior 

rearview mirror’s surface area, but not 

its field of view. This regulation applies 

to all power-driven vehicles with at 

least four wheels that are used for the 

carriage of people or goods, and vehicles 

with less than four wheels that are fitted 

with bodywork which partly or wholly 

encloses the driver. 

ECE 46 requires driver and passenger 

‘‘flat’’ side rearview mirrors as found in 

FMVSS No. 111. ECE 46 differs from 

FMVSS No. 111 in that it also permits 

wide-angle convex mirrors on the 

driver’s side of the vehicle for all classes 

of vehicles except for certain vehicles 

over 7.5 tons, for which they are 

required. 

The ECE 46 regulation also outlines 

requirements for devices for indirect 

vision other than mirrors for vehicles 

with more than eight seating positions 

and those configured for refuse 

collection. Specifically, it contains a 

general requirement that cameramonitor devices, if present, shall 

perceive a visible spectrum and shall 

always render this image without the 

need for interpretation into the visual 

spectrum. The device’s visual display is 

required to be located approximately in 

the same direction as the interior 

rearview mirror. The monitor is 

required to render a minimum contrast 

under various light conditions as 

specified by International Organization 

for Standardization (ISO) 15008:2003 13

and have an adjustable luminance level. 

The regulation also defines detection 

distance, the distance measured at 

ground level from the eye point to the 

extreme point at which a critical object 

can be perceived, as an aspect of 

camera-monitor device performance. 

A January 2008 amendment to ECE 

Regulation 46 required that a cameramonitor system must display to the 

driver a flat horizontal portion of the 

road directly behind the vehicle from 

the rear bumper outward to a distance 

of 2000 mm (6.6 ft). It further specified 

that if an indirect vision device other 

than a camera-monitor is used, a test 

object 50 cm (19.7 in) in height and 30 

cm (11.8 in) in diameter must be visible 

in the specified area. However, in a later 

amendment of UNECE 46 (dated August 

7, 2008) this requirement was removed 

and replaced with the statement, 

‘‘Vehicles may be equipped with 

additional devices for indirect 

vision.’’ 14 This change allows for 

indirect vision systems to be installed 

on European vehicles without meeting 

any performance requirements. 

Canada 

Canada has rearview mirror 

requirements that are essentially 

identical to those in the U.S. All 

passenger cars are required to have a 

driver’s-side outside rearview mirror. 

Passenger cars are also required to be 

equipped with an interior rearview 

mirror providing ‘‘the driver with a field 

of view to the rear that is not less than 

20 degrees measured horizontally 

rearward from the projected eye point 

and extends to the horizon and includes 

a point on the road surface not more 

than 60 m (200 feet) directly behind the 

vehicle.’’ If the interior rearview mirror 

does not meet these requirements, a side 

rearview mirror must be mounted on the 

passenger side of the vehicle opposite 

the driver’s side. 

Japan 

Japanese regulation, Article 44, 

provides a performance based 

requirement for rearview mirrors.15 For 

light vehicles, rearview mirrors must be 

present that enable drivers to check the 

traffic situation around the left-hand 

lane edge and behind the vehicle from 

the driver’s seat.16 The regulation 

requires that the driver be able to 

‘‘visually confirm the presence of a 

cylindrical object 1 m high and 0.3 m 

in diameter (equivalent to a 6-year-old 

child) adjacent to the front or the lefthand side of the vehicle (or the righthand side in the case of a left-hand 

drive vehicle), either directly or 

indirectly via mirrors, screens, or 

similar devices.’’ Article 44 does not 

specify requirements for rear-mounted 

convex mirrors and rearview video 

systems, therefore these devices are 

allowed, but not required under the 

standard. Rear-mounted convex mirrors 

are commonly used as backing aids on 

sport utility vehicles (SUVs) and vans in 

Japan; however, NHTSA is not aware of 

research documenting the effectiveness 

of these mirrors in mitigating backover 

crashes. 

Korea 

The Korean regulation on rearview 

mirrors, Article 50,17 outlines rearview 

mirror requirements for a range of 

vehicles. Article 50 requires a flat or 

convex exterior mirror mounted on the 

driver’s side for passenger vehicles and 

buses with less than 10 passengers. For 

buses, cargo vehicles, and special motor 

vehicles, flat or convex rear-view 

mirrors are required on both sides of the 

vehicle. Article 50 does not address 

rear-mounted convex mirrors and 

rearview video systems, therefore these 

devices are allowed, but not required 

under the standard. Again, rearmounted convex mirrors are commonly 

used as backing aids on SUVs and vans 

in Korea; however, NHTSA is not aware 

of research documenting the 

effectiveness of these mirrors in 

mitigating backover crashes. 

IV. Backover Safety Problem 

Based on our information to date, 

NHTSA has found that the problem of 

backovers claims the lives of hundreds 

of people every year. NHTSA defines 

backover as a specifically-defined type 

of incident, in which a non-occupant of 

a vehicle (i.e., a pedestrian or cyclist) is 

struck by a vehicle moving in reverse. 

However, because many backovers 

occur off public roadways, in areas such 

as driveways and parking lots, NHTSA’s 

ordinary methodologies for collecting 

data as to the specific numbers and 

circumstances of backover incidents 

have not always given the agency a 

complete picture of the scope and 

circumstances of these types of 

incidents. The following sections detail 

NHTSA’s attempts to both quantify the 

number of backover incidents and 

determine their nature. 

A. Injuries and Fatalities in Backing 

Incidents 

In response to SAFETEA–LU Sections 

2012 and 10305, NHTSA developed the 

Not in Traffic Surveillance (NiTS) 

system to collect information about all 

nontraffic crashes, including nontraffic 

backing crashes. NiTS provided 

information on these backing crashes 

9482 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

18Fatalities and Injuries in Motor Vehicle Backing 

Crashes, NHTSA Report to Congress (2008). 

19 Id. 

that occurred off the traffic way and 

which were not included in NHTSA’s 

Fatality Analysis Reporting System 

(FARS) or the National Automotive 

Sampling System—General Estimates 

System (NASS–GES). The subset of 

backing crashes that involve a 

pedestrian, bicyclist, or other person not 

in a vehicle, is referred to as 

‘‘backovers.’’ This is distinguished from 

the larger category of ‘‘backing crashes,’’ 

which would include such nonbackover events such as a vehicle going 

in reverse and colliding with another 

vehicle, or a vehicle backing off an 

embankment or into a stationary object. 

While the primary purpose of this 

rulemaking is to prevent backovers, any 

technology that improves rear visibility 

should have a positive effect on backing 

crashes in general. 

Based on 2002–2006 data from FARS 

and NASS–GES, and 2007 data from 

NiTS, NHTSA estimates that 463 

fatalities and 48,000 injuries a year 

occur in traffic and nontraffic backing 

crashes.18 Most of these injuries are 

minor injuries, but an estimated 6,000 

per year are incapacitating injuries. 

Overall, an estimated 65 percent (302) of 

the fatalities and 62 percent (29,000) of 

the injuries in backing crashes occurred 

in nontraffic situations. 

With regard to injuries and fatalities 

related specifically to backovers, these 

account for an estimated 63 percent 

(292) of the fatalities and 38 percent 

(18,000) of the injuries in backing 

crashes for all vehicles (cars, light trucks 

or vans, heavy trucks, and other/ 

multiple vehicles). Other backing crash 

scenarios account for an estimated 171 

fatalities (37 percent) and 30,000 

injuries (62 percent) per year. Table 1 

shows the fatalities and injuries in all 

backing crashes. Table 1 also 

demonstrates that backover victims tend 

to be more seriously injured than 

individuals in other backing crashes 

(i.e., non-backover crash incidents). In 

fact, more than half (10,000 of 18,000) 

of the injuries in backovers are more 

severe than possible (minor) injuries. 

TABLE 1—ANNUAL ESTIMATED FATALITIES AND INJURIES IN ALL BACKING CRASHES FOR ALL VEHICLES 19

Injury severity Total Backovers Other backing crashes 

Estimated 

total 

Sample 

count 

Estimated 

total 

Sample 

count 

Estimated 

total 

Sample 

count 

Fatalities ........................................................................... 463 1,610 292 716 171 894 

Incapacitating Injury ......................................................... 6,000 304 3,000 131 3,000 173 

Non-incapacitating Injury ................................................. 12,000 813 7,000 372 5,000 441 

Possible Injury .................................................................. 27,000 929 7,000 179 20,000 750 

Injured Severity Unknown ................................................ 2,000 48 1,000 23 2,000 25 

Total Injuries ............................................................. 48,000 2,094 18,000 705 30,000 1,389 

Source: FARS 2002–2006, NASS–GES 2002–2006, NiTS 2007. 

Note: Estimates may not add up to totals due to independent rounding. 

B. Vehicle Type Involvement in Backing 

Incidents 

Most backover fatalities and injuries 

involve passenger vehicles. As indicated 

in Table 2, 78 percent of the backover 

fatalities and 95 percent of the backover 

injuries involved passenger vehicles. An 

estimated fifteen percent (68) of the 

backing crash fatalities occur in 

multivehicle crashes, and an estimated 

thirteen percent (62) occur in singlevehicle non-collisions such as 

occupants who fall out of and are struck 

by their own backing vehicles. About 

half of the backing crash injuries (20,000 

per year) occur in multivehicle crashes 

involving backing vehicles. Table 3 

indicates that all major passenger 

vehicle types (cars, utility vehicles, 

pickups, and vans) are involved in 

backover fatalities and injuries. 

However, the data indicate that some 

vehicles may have a greater risk of 

involvement in backing crashes than 

other vehicles. Table 3 illustrates that 

pickup trucks and utility vehicles are 

overrepresented in backover fatalities 

when compared to all non-backing 

traffic injury crashes and to their 

proportion to the passenger vehicle 

fleet. 

TABLE 2—INJURIES AND FATALITIES AND INJURIES BY BACKING CRASH TYPE FOR ALL VEHICLES

Backing crash scenarios 

All vehicles Passenger vehicles 

Fatalities Injuries Fatalities Injuries 

Backovers: Striking Nonoccupant .................................................................................... 292 18,000 228 17,000 

Backing: Striking Fixed Object ........................................................................................ 33 2,000 33 2,000 

Backing: Noncollision ....................................................................................................... 62 1,000 53 1,000 

Backing: Striking/Struck by Other Vehicle ....................................................................... 68 24,000 39 20,000 

Backing: Other ................................................................................................................. 8 3,000 8 3,000 

Total Backing ............................................................................................................ 463 48,000 361 43,000 

Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9483 

TABLE 3—PASSENGER VEHICLE BACKOVER FATALITIES AND INJURIES BY VEHICLE TYPE

Backing vehicle type Fatalities 

Percent 

of 

fatalities 

Estimated 

injuries 

Estimated 

percent of 

injuries 

Percent 

of vehicles in 

non-backing traffic 

injury 

crashes 

Percent 

of fleet 

Car ....................................................................................................... 59 26 9,000 54 62 58 

Utility Vehicle ....................................................................................... 68 30 3,000 20 14 16 

Van ....................................................................................................... 29 13 1,000 6 8 8 

Pickup .................................................................................................. 72 31 3,000 18 15 17 

Other Light Vehicle .............................................................................. 0 0 * 2 1 <1 

Passenger Vehicles ............................................................................. 228 100 17,000 100 100 100 

Source: FARS 2002–2006, NASS–GES 2002–2006, NiTS 2007. 

Note: * indicates estimate less than 500, estimates may not add up to totals due to independent rounding. 

C. Age Involvement in Backing Incidents 

Table 4 contains the age of the 

backover victim for fatalities and 

injuries for all backovers as well as 

backovers involving passenger vehicles. 

Table 4 also details the proportion of the 

United States (U.S.) population in each 

age category from the U.S. Census 

Bureau’s Population Estimates Program 

for comparison. Similar to previous 

findings, backover fatalities 

disproportionately affect children under 

5 years old and adults 70 or older. When 

restricted to backover fatalities 

involving passenger vehicles, children 

under 5 account for 44 percent of the 

fatalities, and adults 70 and older 

account for 33 percent. The difference 

in the results between all backovers and 

passenger vehicle backovers occurs 

because large truck backovers, which 

are excluded from the passenger vehicle 

calculations, tend to affect adults of 

working age. 

TABLE 4—ALL BACKOVER FATALITIES AND INJURIES BY AGE OF VICTIM

Age of victim Fatalities 

Percent 

of 

fatalities 

Estimated 

injuries 

Estimated 

percent of 

injuries 

Sample 

count of 

injuries 

Percent of 

population 

All Vehicles: 

Under 5 ..................................................................................... 103 35 2,000 8 37 7 

5–10 .......................................................................................... 13 4 * 3 33 7 

10–19 ........................................................................................ 4 1 2,000 12 75 14 

20–59 ........................................................................................ 69 24 9,000 48 383 55 

60–69 ........................................................................................ 28 9 2,000 8 54 8 

70+ ............................................................................................ 76 26 3,000 18 107 9 

Unknown ................................................................................... * 2 16 

Total ................................................................................... 292 100 18,000 100 705 100 

Passenger Vehicles: 

Under 5 ..................................................................................... 100 44 2,000 9 35 7 

5–10 .......................................................................................... 10 4 1,000 3 30 7 

10–19 ........................................................................................ 1 1 2,000 12 71 14 

20–59 ........................................................................................ 29 13 8,000 46 319 55 

60–69 ........................................................................................ 15 6 1,000 8 46 8 

70+ ............................................................................................ 74 33 3,000 19 95 9 

Unknown ................................................................................... * 2 12 

Total ................................................................................... 228 100 17,000 100 608 100 

Source: U.S. Census Bureau, Population Estimates Program, 2007 Population Estimates; FARS 2002–2006, NASS–GES 2002–2006, NiTS 

2007. 

The proportion of backover injuries 

by age group is more similar to the 

proportion of the population than for 

backover fatalities. However, while 

children under 5 years old appear to be 

slightly overrepresented in backover 

injuries compared to the population, 

adults 70 and older appear to be greatly 

overrepresented. One reason for the 

relatively large proportion of injuries in 

backover crashes among older adults 

may be that backovers involving 

younger nonoccupants may not result in 

an injury while the same backover 

involving an older nonoccupant may 

result in a fall and a broken bone. 

Table 5 presents passenger vehicle 

backover fatalities by year of age for 

victims less than 5 years old. Out of all 

backover fatalities involving passenger 

vehicles, 26 percent (60 out of 228) of 

victims are 1 year of age and younger. 

9484 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

20Fatalities and Injuries in Motor Vehicle Backing 

Crashes, NHTSA Report to Congress (2008). 

21Since SCI investigates as many relevant cases 

that they are notified about as possible and not on 

a statistical sampling of incidents, results are not 

representative of the general population. 

22The data obtained for the SCI cases cited in this 

report are based on preliminary case information. 

Data are subject to change based on final 

investigative findings. 23Note that one or more cases examined involved 

multiple victims, causing the total of the path 

breakdown scenarios to be 53 rather than 52. 

24Mazzae, E. N., Barickman, F. S., Baldwin, G. H. 

S., and Ranney, T. A. (2008). On-Road Study of 

Drivers’ Use of Rearview Video Systems 

(ORSDURVS). National Highway Traffic Safety 

Administration, DOT 811 024. 

TABLE 5—BREAKDOWN OF BACKOVER

FATALITIES AND INJURIES INVOLVING

PASSENGER VEHICLES FOR VICTIMS

UNDER AGE 5 YEARS

Age of victim 

(years) 

Number of 

fatalities 

0 ................................................ <1 

1 ................................................ 59 

2 ................................................ 23 

3 ................................................ 14 

4 ................................................ 3 

Total ................................... 100 

Note: Estimates may not add to totals due 

to independent rounding. 

Source: U.S. Census Bureau, Population 

Estimates Program, 2007 Population Estimates; FARS 2002–2006, NASS–GES 2002– 

2006, NiTS 2007. 

D. Special Crash Investigation Backover 

Case Summary 

In addition to collecting policereported backovers through NHTSA’s 

data collection infrastructure, NHTSA’s 

efforts to understand backover incidents 

have included a Special Crash 

Investigation (SCI) program. The SCI 

program was created to examine the 

safety impact of rapidly changing 

technologies and to provide NHTSA 

with early detection of alleged or 

potential vehicle defects. 

SCI began investigating cases related 

to backovers in October 2006.20 SCI 

receives notification of potential 

backover cases from several different 

sources including media reports, police 

and rescue personnel, contacts within 

NHTSA, reports from the general public, 

as well as notifications from the NASS. 

As of July 1, 2008, SCI had received a 

total of 52 notifications from a 

combination of all sources regarding 

backovers.21 For the purpose of the SCI 

cases, an eligible backover was defined 

as a light passenger vehicle where the 

back plane strikes or passes over a 

person who is either positioned to the 

rear of the vehicle or is approaching 

from the side. SCI primarily focuses on 

cases involving children; however, it 

investigates some cases involving 

adults. The majority of notifications 

received do not meet the criteria for case 

assignment. Typically the reasons for 

not pursuing further include: 

Æ The reported crash configuration is 

outside of the scope of the program, 

Æ Minor incidents with no fatally or 

seriously injured persons, or 

Æ Incidents where cooperation can 

not be established with the involved 

parties. 

As an example, many reported 

incidents are determined to be side or 

frontal impacts, which exclude them 

from the program. NHTSA requests that 

commenters submit any other existing 

backover incident data that could aid in 

providing a clearer picture of the range 

of backover accidents. 

The SCI effort to examine backover 

crashes includes an on-site inspection of 

the scene and vehicle, as well as 

interviews of the involved parties when 

possible. When an on-site investigation 

is not possible, backover cases are 

investigated remotely through an 

examination of police-provided reports 

and photos as well as interviews with 

the involved parties. For each backover 

case investigated, a case vehicle 

visibility study is also conducted to 

determine the vehicle’s blind zones and 

also to determine at what distance 

behind the vehicle the occupant may 

have become visible to the driver. 

Through July 2008, NHTSA had 

completed special crash investigations 

of 52 backover cases.22 The 52 backing 

vehicles were comprised of 17 

passenger cars, 21 sport utility vehicles, 

and 14 pickup trucks. Only 4 of the 

cases (8 percent) contained vehicles 

equipped with a backup or parking aid. 

Eighty-eight percent of the backover 

crashes (46 of the 52) involved children, 

ranging in age from less than 1 year old 

up to 13 years old, who were struck by 

vehicles. Adults were generally 

excluded from the study unless they 

were seriously injured or killed or if the 

backing vehicles were equipped with 

backing or parking aids. A total of 6 

cases were investigated involving struck 

adults. Of the 52 backover cases, exactly 

half (26) involved fatally injured 

nonoccupants. 

A breakdown of the victim’s path of 

travel prior to being struck is as follows: 

24 were approaching from the right or 

left of the vehicle, 19 were stationary 

behind the vehicle, 10 were unknown, 

and one was ‘‘other.’’ 23

E. Assessment of Backover Crash Risk 

by Pedestrian Location 

NHTSA believes it would be helpful 

to know whether and to what degree the 

pedestrian’s location at the start of a 

vehicle’s backing plays a part in the 

likelihood of the pedestrian being 

struck. As such, NHTSA used data from 

a recent NHTSA study of drivers’ 

backing behavior 24 to estimate the 

relative risk of a pedestrian colliding 

with a vehicle during a backing 

maneuver. 

A Monte Carlo simulation was used to 

calculate a probability-based risk 

weighting for a test area centered behind 

the vehicle. The probability-based risk 

weightings for each grid square were 

based on the number of pedestrianvehicle backing crashes predicted by the 

simulation for trials for which the 

pedestrian was initially (i.e., at the time 

that the vehicle began to back up) in the 

center of one square of the grid of 1-foot 

squares. A total of 1,000,000 simulation 

trials were run with the pedestrian 

initially in the center of each square. 

Additional details about assumptions 

relating to the vehicle and pedestrian, as 

well as the simulation, are presented in 

Appendix A. 

Figure 1 summarizes the calculated 

relative crash risk for each grid square. 

Note that the white shaded area does 

not have a zero backover risk; it merely 

has a low (less than 15 percent of the 

maximum) risk. This analysis shows 

that the probability of crash decreases 

rapidly as the pedestrian’s initial 

location is moved back, further away, 

from the rear bumper of the vehicle. 

There are substantial side lobes, giving 

pedestrians some risk of being hit even 

though they were not initially directly 

behind the vehicle. The results suggest 

that coverage of an area 12 feet wide by 

36 feet long centered behind the vehicle 

would address pedestrian locations 

having relative crash risks of 0.15 and 

higher. To address crash risks of 0.20 

and higher, an area 7 feet wide and 33 

feet long centered behind the vehicle 

would need to be covered. NHTSA 

seeks comment on the coverage area that 

is needed to establish a reasonable 

safety zone behind the vehicle. 

BILLING CODE 4910–59–P 

Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9485 

BILLING CODE 4910–59–C 


EP04MR09.000</GPH>
9486 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

25 2008 Ward’s Automotive Yearbook. 

26Rear cross-view mirrors have been available on 

the Toyota 4Runner base model vehicles since MY 

2003. 

27SAFETEA–LU, Sec. 1109, 119 Stat. 1168. 

28Mazzae, E.N. and Garrott, W.R., Experimental 

Evaluation of the Performance of Available 

Backover Prevention Technologies, NHTSA 

Technical Report No. DOT HS 810 634, September 

2006. 

V. Technologies for Improving Rear 

Visibility 

Since the early 1990s, NHTSA has 

actively researched approaches to 

mitigate backing crashes for heavy and 

light vehicles by assessing the 

effectiveness of various backing aid 

technologies. In recent years, 

manufacturers have added object 

detection sensors and video cameras to 

vehicles to aid drivers in performing 

backing maneuvers. According to 

Ward’s 2008 Automotive Yearbook, 

backing aids utilizing sensors and/or 

video cameras were installed in 

approximately 14 percent of model year 

2007 light vehicles.25 While these 

systems are becoming increasingly 

available, they have typically been 

marketed as parking aids to help drivers 

detect and avoid obstacles in low-speed 

backing scenarios. 

To assess whether or not these 

systems could also be used to detect 

pedestrians, the agency has, and 

continues to, evaluate them. The agency 

has also evaluated rear-mounted convex 

mirrors and rearview video systems. In 

the following sections, we outline the 

technologies we have evaluated, 

research conducted by the agency and 

others, and offer our preliminary 

observations on how they would meet 

the Congressional directive to improve 

the rear visibility of current vehicles. 

A. Rear-Mounted Convex Mirrors 

Description 

Rear-mounted convex mirrors are 

mirrors with a curved reflective surface 

thereby providing a wider field of view 

than plane (i.e., flat) mirrors. These 

mirrors can be mounted at the upper 

center of the rear window with the 

reflective surface pointing at the ground 

(commonly referred to as backing 

mirrors, under mirrors, or ‘‘look-down’’ 

mirrors), the driver’s side upper corner 

of the vehicle (commonly seen on 

delivery vans or mail delivery trucks 

and called ‘‘corner mirrors’’), or 

integrated into the inside face of both 

rearmost pillars (called ‘‘cross-view’’ 

mirrors). While center or cornermounted convex rearview mirrors show 

the driver an area behind the vehicle, 

rear cross-view mirror pairs are 

intended to aid a driver when backing 

into a right-of-way by showing objects 

approaching on a perpendicular path 

behind the vehicle. 

To view the area behind a vehicle, 

interior rear-mounted convex mirrors 

can be viewed directly by the driver, if 

in his direct line of sight, or they may 

be looked at indirectly by viewing their 

reflection in the interior or exterior 

rearview mirror. In the case of a rear 

‘‘look-down mirror,’’ the driver can 

either glance rearward directly at this 

mirror, or view its reflection in the 

interior rearview mirror. For a rear 

convex corner mirror, the driver must 

look into the driver’s side (i.e., exterior) 

rearview mirror to view the reflection of 

the rear convex corner mirror. In the 

case of rear cross-view mirrors, they can 

be viewed directly by the driver or 

indirectly by viewing their reflection in 

the interior rearview mirror. 

In the U.S., rear-mounted convex 

mirrors are sometimes seen on delivery 

trucks and vans. Rear-mounted convex 

mirrors are primarily available as 

aftermarket products in the U.S., but are 

also available as original equipment on 

one sport utility vehicle.26 In Korea and 

Japan, rear-mounted convex mirrors are 

used on small school buses, short 

delivery trucks, and some multipurpose 

vehicles (e.g., SUVs) to allow drivers to 

view areas behind a vehicle. 

While rear convex cross-view mirrors 

are available as aftermarket products 

that mount to the inside of the rear 

window for all passenger car body 

types, this is not the case for look down 

mirrors. Rear convex look-down or 

corner convex mirrors need to have a 

rear window that is vertically aligned 

with the rear of the vehicle (such as a 

station wagon, SUV or van) in order to 

have a clear view of the area behind the 

vehicle. 

Research 

NHTSA has conducted research on 

rear-mounted convex mirrors for use on 

medium straight trucks and to a limited 

extent, passenger vehicles (i.e., cars, 

trucks, vans, SUVs). The research and 

how its results may be related to the 

improvement of rear visibility are 

discussed below. 

Passenger Vehicle Research 

In response to Section 10304 of the 

Safe, Accountable, Flexible, Efficient 

Transportation Equity Act: A Legacy for 

Users (SAFETEA–LU),27 NHTSA 

conducted a study to evaluate methods 

to reduce the incidence of injury, death, 

and property damage caused by backing 

collisions of passenger vehicles.28 The 

examination of two convex mirror 

systems revealed that pedestrians and 

objects were not visible in some areas 

directly behind the vehicle (this area 

could be described as the area bounded 

by the vertical planes formed by the 

sides of the vehicle, and extending 

rearward). The research also found that 

the convexity of the mirrors caused 

significant image distortion, and 

reflected objects were difficult to 

discern. It is unknown if this issue can 

be addressed in future designs. For the 

tested designs, concentrated glances 

were necessary to identify the nature of 

rear obstacles; it is not known if a driver 

making quick glances prior to initiating 

a backing maneuver would allocate 

sufficient time to allow recognition of 

an obstacle or pedestrian shown in the 

mirror. 

Current Mirror Research 

NHTSA is currently evaluating the 

image quality (distortion and 

minification) and field of view of rearmounted convex mirrors. The mirror 

types being examined include an 

aftermarket rear convex look-down 

mirror, aftermarket rear corner convex 

mirror, aftermarket rear convex crossview mirrors designed for SUVs and 

passenger cars (e.g., sedans, coupes), 

and original equipment rear convex 

cross-view mirrors on a 2003 Toyota 

4Runner. 

Figure 2 below illustrates the types of 

measurements that NHTSA plans to 

collect to evaluate the image quality and 

field of view for rear convex mirrors. As 

illustrated in the Figure, using a test 

device that simulates a 1-year-old child, 

the rear convex look-down mirror shows 

an area directly behind a vehicle (a 2007 

Honda Odyssey minivan) but beyond 15 

feet from the bumper, the image could 

not be discerned. 

BILLING CODE 4910–59–P 

Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9487 

BILLING CODE 4910–59–C 


EP04MR09.001</GPH>
9488 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

29Mazzae, E.N., and Garrott, W.R., Experimental 

Evaluation of the Performance of Available 

Backover Prevention Technologies for Medium 

Straight Trucks, NHTSA Technical Report No. DOT 

HS 810 865, November 2007. 30Measured minutes of arc subtended by the test 

object were first linearly extrapolated to estimate 

the effects of differences in the distance from the 

driver eyepoint to the side rearview mirror and the 

distance from the side rearview mirror to the rear 

corner convex mirror. Two-dimensional linear 

interpolation was then used to correct for reducing 

the vehicle width from the 7.0 feet for the step van 

to the 6.0 feet more typical of light passenger 

vehicle and for estimating minutes of arc subtended 

at the four locations, A through D. Note that 

estimates based upon multiple multi-linear 

extrapolation/interpolation were made because they 

could be done quickly using data that NHTSA had 

previously collected. 

Using the same 1-year-old child-sized 

test device, Figure 3 illustrates the 

measured field of view for an exemplar 

rear convex cross-view mirror system. 

The area behind the vehicle cannot be 

seen, rather, only the area that extends 

outward from both rear corners of the 

vehicle. 

NHTSA previously evaluated the 

quality of images displayed by a rear 

corner convex mirror mounted on a 

1996 Grumman-Olsen step van with a 

12-foot long box.29 Using those data, an 

analysis was performed in which linear 

extrapolation and two-dimensional 

interpolation 30 were applied to estimate 

at which of four locations behind the 

vehicle a 1-year-old child dummy (i.e., 

anthropomorphic test device, or ATD) 

could be visible to a driver using a rear 

corner convex mirror. The four locations 

assessed are labeled A through D in 

Figure 4. 


EP04MR09.002</GPH>
Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9489 

The reflected image of the 1-year-old 

dummy becomes less minified and is 

easier for the driver to discern as the 

location of the dummy moves either 

forward towards the rear bumper of the 

vehicle or laterally towards the driver’s 

side of the vehicle. Therefore, for a 

vehicle for which the dummy is visible 

at Point A, the dummy is expected to be 

visible anywhere across the entire width 

of the vehicle for distances up to at least 

10 feet from the vehicle’s rear bumper. 

Estimated visibility of the 1-year-old 

dummy for each of the four locations 

(identified in Figure 4) for 9 vehicles is 

shown in Table 6. 

TABLE 6—VISIBILITY OF A 1-YEAR-OLD CHILD DUMMY USING A CORNER REAR CROSS-VIEW MIRROR

Year Make Model Can see 

Point A? 

Can see 

Point B? 

Can see 

Point C? 

Can see 

Point D? 

2008 ............ Chevrolet ............... Express ................. No ......................... No ......................... No ......................... Yes. 

2003 ............ Volvo ..................... XC90 ..................... No ......................... No ......................... Yes ........................ Yes. 

2005 ............ Nissan ................... Armada ................. No ......................... No ......................... No ......................... Yes. 

2007 ............ Saturn ................... Vue ........................ No ......................... No ......................... Yes ........................ Yes. 

2007 ............ Jeep ...................... Commander .......... No ......................... No ......................... Yes ........................ Yes. 

2008 ............ Toyota ................... Highlander ............. No ......................... No ......................... Yes ........................ Yes. 

2007 ............ Ford ....................... Edge ...................... No ......................... No ......................... Yes ........................ Yes. 

2005 ............ Chevrolet ............... Uplander ............... No ......................... No ......................... No ......................... Yes. 

2003 ............ Toyota ................... 4Runner ................ No ......................... No ......................... Yes ........................ Yes. 


EP04MR09.003</GPH>
9490 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

31PRIA, section VI. 

32Mazzae, E.N. and Garrott, W.R., Experimental 

Evaluation of the Performance of Available 

Backover Prevention Technologies, NHTSA 

Technical Report No. DOT HS 810 634, September 

2006. 

As the table indicates, it is not 

expected that a driver could see the 1- 

year-old dummy when the dummy is 

located directly behind the passenger’s 

side of the vehicle at a distance of 6 or 

10 feet back from the vehicle’s rear 

bumper. The quality of the reflected 

image is better on the vehicle’s 

centerline, with the dummy expected to 

be visible for six out of nine vehicles 

when it is located 10 feet back from the 

rear bumper and visually discernable to 

the driver for all nine vehicles when it 

is only 6 feet aft of the rear bumper. 

This mirror research is scheduled to 

be completed in 2009 and will be 

summarized in a published NHTSA 

report thereafter. Along with comments 

received to this notice, NHTSA hopes to 

use this research information in the 

development of a proposal. 

Observations 

Some advantages of rear-mounted 

convex mirrors include that when 

compared to video cameras and object 

detection sensors, they are relatively 

inexpensive (e.g., less than $40 retail as 

an aftermarket product) and have the 

potential to last the life of the vehicle. 

They also provide a wider field of view 

than that provided by plane mirrors. 

However, they also possess inherent 

disadvantages. In general, convex 

mirrors compress (i.e., minify) and 

distort the image of reflected objects in 

their field of view. This image distortion 

and image minification make objects 

and pedestrians appear very narrow and 

difficult for the driver to discern and 

identify. These aspects of image quality 

worsen as the length of the vehicle 

increases. 

Rear cross-view mirrors are 

positioned to show an area to the side 

and rear of the vehicle but they do not 

provide a good view of the area directly 

behind the vehicle (the area bounded by 

two imaginary planes tangent to the 

sides of the vehicle. As such, a 

pedestrian or object in this area could be 

invisible to the driver. They can 

however, help drivers see objects 

approaching the rear of the vehicle 

along a perpendicular path. NHTSA is 

aware that single rear convex look-down 

mirrors are commonly found on SUVs 

and vans in Korea and Japan. However, 

we are unaware of any publicly 

available studies that have been 

conducted to assess the effectiveness of 

these mirrors in improving rear 

visibility. We seek comment on the 

availability of any such studies. 

B. Rearview Video Systems 

Description 

A growing number of vehicles in the 

U.S. are equipped with rearview video 

systems. These systems can permit a 

driver to see much of the area behind 

the vehicle via a video display showing 

the image from a video camera mounted 

on the rear of the vehicle. The images 

may be presented to the driver using an 

existing screen in the vehicle, such as a 

navigation system or multifunction 

display screen, or by adding a display 

incorporated into the dashboard or 

interior rearview mirror. 

Costs for these rearview video systems 

are estimated at approximately $58–$88 

for vehicles equipped with a navigation 

system or other type of multi-function 

visual display, to $158–$189 for 

vehicles requiring a dashboard-mounted 

display screen, or $173–$203 for 

vehicles with an RV display integrated 

into the interior rearview mirror.31

Research 

Recent research on rearview video 

systems conducted by NHTSA and our 

observations about the research are 

presented below. 

NHTSA Testing in Support of 

SAFETEA–LU 

In response to Section 10304 of 

SAFETEA–LU, NHTSA examined three 

rearview video systems (RV): One in 

combination with original equipment 

rear parking sensors, one aftermarket 

system combining both RV and parking 

sensor technologies, and one original 

equipment RV system.32 This 

examination of RV systems included 

assessment of their field of view and 

their potential to provide drivers with 

information about obstacles behind the 

vehicle. 

Through this study, the agency made 

the following observations. The 

rearview video systems examined 

provided a clear image of the area 

behind the vehicle in daylight and 

indoor lighting conditions. RV systems 

displayed images of pedestrians or 

obstacles behind the vehicle to a 

substantial range of 23 feet or more, 

except for an area within 8–12 inches of 

the rear bumper at ground level. Beyond 

the rear bumper, the rearview video 

systems also displayed areas wider than 

50 feet. 

The location and angle at which the 

rearview video camera is mounted on 

the back of the vehicle affects the size 

of the field of view provided by the 

system. The longitudinal range of the 

images displayed by the two original 

equipment RV systems tested differed 

significantly. One rearview video 

system’s camera presented an image 

having a limited vertical angle, resulting 

in a substantially shorter longitudinal 

range along the centerline of the vehicle 

(ending at approximately 23 feet from 

the rear bumper at ground level). For a 

3-year-old child dummy centered 2 feet 

behind the vehicle, the shorter visible 

range exhibited by this particular RV 

system caused the top of the dummy’s 

head to be out of view. 

Observations 

We found that RV systems can display 

areas on the ground almost directly 

adjacent to the bumper of the vehicle. 

Furthermore, RV systems offer the 

possibility of a wide field of view, with 

some systems able to show 180 degrees 

behind the vehicle. 

However, during the short course of 

testing, NHTSA also noted some 

operational issues with video camera 

performance in certain weather 

conditions, such as rain and snow. For 

example, rain drops and the buildup of 

ice on the video camera lens can 

significantly reduce the quality of the 

view provided by the RV system. Also, 

in evaluating these technologies we 

have not had the opportunity to assess 

the long-term performance and 

reliability of RV systems, as well as the 

effects of harsh weather conditions on 

their long-term operation. 

C. Sensor-Based Rear Object Detection 

Systems 

Description 

Sensor-based object detection systems 

use electronic sensors that transmit a 

signal which, if an obstacle is present in 

a sensor’s detection field, bounces the 

signal back to the sensor producing a 

positive ‘‘detection’’ of the obstacle. 

These sensors detect objects in the 

vicinity of a vehicle at varying ranges 

depending on the technology. To date, 

commercially-available object detection 

systems have been based on short-range 

ultrasonic technology or longer range 

radar technology, although advanced 

infrared sensors are under development 

as well. 

Sensor-based object detection systems 

have been available for over 15 years as 

aftermarket products and for a lesser 

period as original equipment. Original 

equipment systems have been marketed 

as a convenience feature or ‘‘parking 

aid’’ for which the vehicle owner’s 

manual can contain language denoting 

Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9491 

33PRIA, section VI. 

34Mazzae, E.N. and Garrott, W.R., Experimental 

Evaluation of the Performance of Available 

Backover Prevention Technologies, NHTSA 

Technical Report No. DOT HS 810 634, September 

2006. 

35 ISO 17386:2004 Transport information and 

control systems—Manoeuvring Aids for Low Speed 

Operation (MALSO)—Performance requirements 

and test procedures. 

36Note that average backing speed was found to 

be 2.26 mph in NHTSA’s ‘‘On-Road Study of 

Drivers’ Use of Rearview Video Systems 

(ORSDURVS).’’ Mazzae, E.N., Barickman, F.S., 

Baldwin, G.H.S., and Ranney, T.A. (2008). National 

Highway Traffic Safety Administration, DOT 811 

024, page 34. 

37Mazzae, E.N., Barickman, F.S., Baldwin, 

G.H.S., and Ranney, T.A. (2008). On-Road Study of 

Drivers’ Use of Rearview Video Systems 

(ORSDURVS). National Highway Traffic Safety 

Administration, DOT 811 024. 

38Mazzae, E.N. and Garrott, W.R., Experimental 

Evaluation of the Performance of Available 

Backover Prevention Technologies, NHTSA 

Technical Report No. DOT HS 810 634, September 

2006. 39Mazzae, E.N. and Garrott, W.R., Experimental 

Evaluation of the Performance of Available 

Backover Prevention Technologies for Medium 

Straight Trucks, NHTSA Technical Report No. DOT 

HS 810 865, November 2007. 40Paine, M., Macbeth, A., and Henderson, M. 

(2003). The Danger to Young Pedestrians from 

Reversing Motor Vehicles. 18th International 

Technical Conference on the Enhanced Safety of 

Vehicles. Paper Number 466. 

sensor performance limitations with 

respect to detecting children or small 

moving objects. Aftermarket systems, 

however, are frequently marketed as 

safety devices for warning drivers of the 

presence of small children behind the 

vehicle. 

NHTSA has investigated the cost of 

sensor-based rear object detection 

systems. Currently, we estimate the cost 

of a backing system based on ultrasonic 

technology to be $51–$89 and the cost 

of a system based on radar technology 

to be approximately $92.33

Research 

NHTSA Research in Support of 

SAFETEA–LU 

NHTSA examined eight sensor-based 

original equipment and aftermarket rear 

parking systems in response to Section 

10304 of the SAFETEA–LU mandate.34

NHTSA conducted testing to measure 

the object detection performance of 

short range sensor-based systems. 

Measurements included static field of 

view (i.e., both the vehicle and test 

objects were static), static field of view 

repeatability, and dynamic detection 

range for different laterally moving test 

objects. The agency assessed the 

system’s ability to detect a 74-inch-tall 

adult male walking in various directions 

to the rear of the vehicle. Detection 

performance was also evaluated in a 

series of static and dynamic tests with 

1-year-old and 3-year-old children. 

Sensor-based systems tested were 

generally inconsistent and unreliable in 

detecting pedestrians, particularly 

children, located behind the vehicle. 

Testing showed that, in most cases, 

pedestrian size affected detection 

performance, as adults elicited better 

detection response than 1 or 3-year-old 

children. Specifically, each system 

could generally detect a moving adult 

pedestrian (or other objects) behind a 

stationary vehicle; however, each 

system exhibited some difficulty in 

detecting moving children. The sensorbased systems tested were found to 

operate reliably (i.e., without 

malfunction), with the exception of one 

aftermarket ultrasonic system that 

malfunctioned after only a few weeks, 

rendering it unavailable for use in 

remaining tests. 

While examining the consistency of 

system detection performance, the 

agency observed that each sensor-based 

system exhibited some degree of 

variability in its detection performance 

and patterns. Specifically, detection 

inconsistencies were generally noticed 

at the periphery of the detection zones 

and typically for no more than 1 foot in 

magnitude. On average, these sensorbased systems had detection zones 

which generally covered an area directly 

behind the vehicle. The system with the 

longest detection range could detect a 3- 

year-old child up to 11 feet from the rear 

bumper (along a 3–5 ft wide strip of area 

along the vehicle’s centerline). The 

majority of systems were unable to 

detect test objects less than 28 inches in 

height. 

The response times of sensor-based 

systems were also evaluated in this 

study. In order for sensor-based 

backover avoidance systems to assist in 

preventing collisions, warnings must be 

generated by the system in a timely 

manner and the driver must perceive 

the warning within sufficient time to 

respond appropriately to avoid a crash. 

With regards to system response times, 

ISO 17386:2004,35 ‘‘Manoeuvring Aids 

for Low Speed Operation (MALSO)— 

Performance requirements and test 

procedures’’, outlines performance 

requirements for sensor-based object 

detection systems. This standard 

recommends a maximum system 

response time of 0.35 seconds. NHTSA’s 

tests showed that the response times for 

the eight tested sensor systems varied 

from 0.18 to 1 second, and only three of 

them met the ISO response time limit. 

For the systems that did not meet the 

recommended 0.35-second limit, it is 

unlikely (assuming typical backing 

speeds 36 and driver reaction times) that 

warnings would be provided to a driver 

in sufficient time to allow the driver to 

bring the vehicle to a stop and avoid a 

possible collision with an obstacle or 

moving child. 

NHTSA Experimental Research: 

Performance of Sensor-Based Rear 

Object Detection Systems 

NHTSA’s 2008 study of drivers’ use of 

rearview video systems 37 involved an 

observation of drivers of vehicles 

equipped with an ultrasonic-based rear 

parking sensor system in addition to an 

RV system. In a staged experimental 

trial in which an unexpected obstacle 

was presented to test participants while 

backing out of a garage, the rear parking 

sensor system on the particular vehicle 

involved in this study detected the 

obstacle and provided a warning 

indication of the presence of the 

obstacle behind the vehicle in 38 

percent (5 out of 13) of the event trials 

for participants with vehicles equipped 

with the combination system. These 

data describing the performance of a 

sensor-based rear parking aid as used by 

average drivers reflect similar detection 

performance deficiencies as have been 

observed in NHTSA’s laboratory testing 

of the detection performance of sensorbased object detection systems.38 39

Paine, Macbeth & Henderson Proximity 

Sensor Research 

Paine, Macbeth & Henderson tested 

the performance of proximity sensor 

backing aids.40 They reported that 

proximity sensors tested exhibited 

limited ability to detect objects for 

vehicles traveling at 5 km/h (3.1 mph) 

or more. According to their conclusions, 

proximity sensors were prone to 

produce ‘‘nuisance alarms’’ in some 

driving situations and were deemed an 

unviable option to reduce backing 

incidents. While the authors suggested 

that a more effective system to mitigate 

backing incidents may be to incorporate 

sensors and wide-angle video camera 

technology, no data were provided to 

support this statement. 

GM Experimental Research on SensorBased Systems for the Reduction of 

Backing Incidents 

GM outlined the functional 

capabilities of their ultrasonic rear park 

assist system. The system was designed 

to detect larger poles and parking 

barriers greater than 7.5 cm in diameter 

with a length of 1.0 meter or more. It 

was not designed to detect objects less 

than 25 cm in height. In addition, the 

system was not designed to detect 

obstacles directly below the bumper or 

under the vehicle. GM notes that 

smaller or thinner objects or pedestrians 

9492 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

41 Instructional materials include the following 

warning: ‘‘If children, someone on a bicycle, or pets 

are behind your vehicle, (ultrasonic rear park assist) 

won’t tell you they are there. You could strike them 

and they could be injured or killed.’’ 

42 Green, C. and Deering, R. (2006). Driver 

Performance Research Regarding Systems for Use 

While Backing. Society of Automotive Engineers, 

Paper No. 2006–01–1982. 

may not be detected by this system, and 

indicates this fact explicitly in the 

system’s instructional materials.41 42

Observations 

The development of sensor-based 

systems for use as parking aids has been 

in progress for at least 15 years. 

Ultrasonic sensors inherently have 

detection performance that varies as a 

function of the degree of sonic 

reflectivity of the obstacle surface. For 

example, objects with a smooth surface 

such as plastic or metal reflect well, 

whereas objects with a textured surface, 

such as clothing, may not reflect as well. 

Radar sensors, which are able to detect 

the water in a human’s body, are better 

able to detect pedestrians, but 

demonstrate inconsistent detection 

performance, especially with regard to 

small children. 

NHTSA is aware that the performance 

of current sensor-based systems can be 

influenced by the algorithms that are 

used for detection. As stated previously, 

these systems are implemented as 

parking aids rather than safety systems 

and thus this may have attributed to the 

observed performance. While it is 

possible to modify the detection 

algorithms of sensor-based object 

detection systems to allow for better 

detection of children, one result of such 

a modification could result in other less 

favorable aspects of system 

performance, such as increased false 

alarms. From a driver confidence 

standpoint, an increase in false alarms 

could have the effect of decreasing the 

system’s overall effectiveness as a 

driver’s desire to use the system 

decreases. 

D. Multi-Technology (Sensor + Video 

Camera) Systems 

Description 

In the context of this document, 

multi-technology backing aid systems 

are those systems that utilize both video 

and sensor-based technologies. Prior to 

MY 2007, these technologies functioned 

independently if both were present on 

a vehicle. Recently, truly integrated 

systems that use data from rear object 

detection sensors to present obstacle 

warnings that are superimposed on the 

RV display image have become 

commercially available. Whether 

integrated or not, vehicles equipped 

with both rearview video and sensor 

technologies have the ability to detect 

obstacles (via a rear parking sensor 

system) and alert a driver (by directing 

their attention to the rearview video 

system display) to the presence of the 

obstacle. 

Research 

As previously mentioned in Part C of 

this section, NHTSA’s work in response 

to Section 10304 of the SAFETEA–LU 

mandate included the measurement of 

the object detection performance of 

short range sensor-based systems. One 

of the systems examined was the 

integrated rearview video and 

ultrasonic-based rear parking aid system 

of a 2007 Cadillac Escalade. This system 

used object detection information from 

an ultrasonic rear parking aid to present 

obstacle warnings to the driver through 

warning symbology superimposed on 

the RV display image. Specifically, a 

warning triangle symbol was shown on 

the RV display image in the 

approximate location of the obstacle. 

While the performance of the ultrasonicbased rear parking aid system showed 

the same issues as other tested systems 

using that sensor technology, the 

presentation of integrated warnings may 

be useful in directing a driver’s 

attention to the image of a rear obstacle 

presented on the rearview video 

display. However, in order to assess the 

effectiveness of this or any other 

integrated system in mitigating backover 

incidents, research with drivers using 

the system is needed. 

Observations 

Testing of the vehicle examined 

showed that the integrated rear parking 

aid and rearview video aspects of the 

backing aid system performed, from a 

sensor point of view, the same as would 

these two technologies if tested 

separately. The performance of the 

backing aid technologies present on this 

vehicle may not represent the 

performance of all such systems 

commercially available today. With 

improved technology integration that 

may utilize image processing to confirm 

the presence of rear obstacles, 

performance enhancements may be 

possible. The agency seeks comment on 

whether any recent studies have been 

performed with other integrated multitechnology backing aid systems. 

E. Future Technologies 

Description 

NHTSA is aware of two additional 

sensor technologies being developed 

that could be used to improve a 

vehicle’s rear visibility; infrared-based 

object detection systems and videobased object recognition systems. As 

with other sensor systems, infraredbased systems emit a signal, which if an 

object is within its detection range, will 

bounce back and be detected by a 

receiver. Rear object detection via video 

camera uses real-time image processing 

capability to identify obstacles behind 

the vehicle and alert the driver of their 

presence. 

Research 

Ongoing NHTSA Backing Crash 

Countermeasure Research 

In addition to the previously 

mentioned rear-mounted convex mirror 

research, NHTSA is currently engaged 

in cooperative research with GM on 

Advanced Collision Avoidance 

Technology relating to backing 

incidents. The ACAT backing systems 

project is assessing the ability of more 

advanced technologies to mitigate 

backing crashes, and refining a tool to 

assess the potential safety benefit of 

these technologies. The focus of the 

ACAT Backing Crash Countermeasure 

Program is to characterize backing 

crashes in the U.S. and investigate a set 

of integrated countermeasures to 

mitigate them at appropriate points 

along the crash timeline (prior to 

entering the vehicle and continuing 

throughout the backing sequence). The 

objective of this research is to estimate 

potential safety benefits or harm 

reduction that these countermeasures 

might provide. A Safety Impact 

Methodology (SIM), consisting of a 

software-based simulation model 

together with a set of objective tests for 

evaluating backing crash 

countermeasures, will be developed to 

estimate the harm reduction potential of 

specific countermeasures. Included in 

the SIM’s methods for estimating 

potential safety benefits will be a 

consideration of assessing and modeling 

unintentional potential disbenefits that 

might arise from a countermeasure. 

Observations 

While these technology applications 

may eventually prove viable, because of 

their early stages of development it is 

not possible at this time to assess their 

ability to effectively expand the visible 

area behind a vehicle. Similarly, the 

completion of NHTSA’s advanced 

technology research effort is not 

expected until calendar year 2011 and 

thus will not occur prior to the 

Congressional deadline. The agency 

seeks comments on the timeframe for 

the commercial availability of these 

technologies, and on any other 

Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9493 

43Mazzae, E.N., Barickman, F.S., Baldwin, 

G.H.S., and Ranney, T.A. (2008). On-Road Study of 

Drivers’ Use of Rearview Video Systems 

(ORSDURVS). National Highway Traffic Safety 

Administration, DOT 811 024. 

advanced technology developments not 

identified here. 

F. Summary and Questions Regarding 

Technologies for Improving Rear 

Visibility 

Given the mandate from Congress to 

improve the rear visibility of vehicles, 

NHTSA’s preliminary assessment of the 

known research to date seems to 

indicate that RV systems have greater 

potential to improve vehicles’ rear 

visibility than sensor-based rear object 

detection systems and rear-mounted 

convex mirrors. However, we believe it 

is premature to limit manufacturers’ 

design options at this time. To this end, 

we put forth the following questions 

and solicit comments on our 

assessments of these technologies, and 

any information on the feasibility of 

alternative approaches or systems. 

(1) While the objective to ‘‘expand the 

required field of view to enable the 

driver of a motor vehicle to detect areas 

behind’’ the vehicle implies 

enhancement of what a driver can 

visually see behind a vehicle, the 

language of the K.T. Safety Act also 

mentions that the ‘‘standard may be met 

by the provision of additional mirrors, 

sensors, cameras, or other technology.’’ 

NHTSA seeks comment regarding the 

ability of object detection sensor 

technology to improve visibility and 

comply with the requirements of the 

Act. 

(2) What specific customer feedback 

have OEMs received regarding vehicles 

equipped with rear parking sensor 

systems? Have any component 

reliability or maintenance issues arisen? 

Is sensor performance affected by any 

aspect of ambient weather conditions? 

(3) What specific customer feedback 

have OEMs received regarding vehicles 

equipped with rearview video systems? 

Have any rearview video system 

component reliability or maintenance 

issues arisen? 

(4) What are the performance and 

usability characteristics of rearview 

video systems and rear-mounted convex 

mirrors in low light (e.g., nighttime) 

conditions? 

(5) Is there data available regarding 

consumers’ and vehicle manufacturers’ 

research regarding backing speed 

limitation, haptic feedback to the driver, 

or use of automatic braking? 

(6) What types of rear visibility 

countermeasures are anticipated to be 

implemented in the vehicle fleet 

through the 2012 timeframe? 

(7) Can rear-mounted convex mirrors 

be installed on light vehicles other than 

SUVs and vans? What is the rationale 

for U.S. manufacturers’ choosing to 

install rear parking sensors and video 

cameras, rather than rear-mounted 

convex mirrors as are commonly 

installed on SUVs and minivans in 

Korea and Japan? NHTSA is particularly 

interested in any information on the 

effectiveness of rear-mounted convex 

mirrors in Korea and Japan. 

(8) NHTSA seeks any available 

research data documenting the 

effectiveness of rear convex cross-view 

mirrors in specifically addressing 

backover crashes. 

(9) NHTSA seeks comment and data 

on whether it is possible to provide an 

expanded field of view behind the 

vehicle using only rear-mounted convex 

mirrors. 

(10) NHTSA is aware of research 

conducted by GM that suggests that 

drivers respond more appropriately to 

visual image-based confirmation of 

object presence than to non-visual 

image based visual or auditory 

warnings. Is there additional research 

on this topic? 

(11) NHTSA requests input and data 

on whether the provision of graphical 

image-based displays (e.g., such as a 

simplified animation depicting rear 

obstacles), rather than true-color, 

photographic visual displays would 

elicit a similarly favorable crash 

avoidance response from the driver. 

(12) To date, rearview video systems 

examined by NHTSA have displayed to 

the driver a rear-looking perspective of 

the area behind the vehicle. Recently 

introduced systems which provide the 

driver with a near 360-degree view of 

the area around the entire vehicle do so 

using a ‘‘birds-eye’’ perspective using 

images from four cameras around the 

vehicle. During backing, it appears that, 

by default, this birds-eye view image is 

presented simultaneously along with 

the traditional rear-facing camera image. 

NHTSA requests data or input on 

whether this presentation method is 

likely to elicit a response from the 

driver that is at least as favorable as that 

attained using traditional, rear-view 

image perspective, or whether this 

presentation is more confusing for 

drivers. 

VI. Drivers’ Use and the Associated 

Effectiveness of Available Technologies 

To Mitigate Backovers 

In order to establish effectiveness 

estimates for different systems which 

may be utilized to mitigate backover 

crashes, the agency has conducted 

research on vehicles equipped with 

such systems, including those utilizing 

ultrasonic and radar sensors and 

rearview video cameras. As with any 

passive technology, NHTSA believes 

that it is reasonable to assume that in 

order for the technology to assist in 

preventing backing crashes, the driver 

must use the technology (e.g., look at 

the video display, if present), perceive 

the indication that a pedestrian or object 

is present, and respond quickly, and 

with sufficient force applied to the 

brake pedal, to bring the vehicle to a 

stop. While we have previously 

discussed the performance of the 

technologies, this section will outline 

what the agency knows about driver use 

and the resulting effectiveness of 

technologies that could be used to 

mitigate backover crashes. 

NHTSA has not conducted system 

effectiveness research with drivers for 

all of the four system types discussed in 

this notice. However, that relevant 

research NHTSA and industry have 

conducted is summarized here. 

A. Rear-Mounted Convex Mirrors 

NHTSA has not conducted research 

focused on examining driver’s use of 

mirrors to aid in the performance of 

backing maneuvers. However, NHTSA’s 

study of drivers’ use of rearview video 

systems during staged and naturalistic 

backing maneuvers did produce data 

regarding drivers’ use of the side and 

interior rearview mirrors as well as 

direct glance behavior.43 This behavior 

suggests that drivers would use the 

mirrors. Table 7 shows that the mean 

percentage of total glance time during a 

backing maneuver in which drivers 

glanced at the driver-side mirror, 

passenger-side mirror, and interior 

rearview mirror. Independent of the 

presence of a backing aid, drivers spent 

over 25 percent of the time during a 

backing maneuver glancing rearward 

over their right shoulder. 

9494 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

44 Id. 

45Note that due to the close proximity of the 

mirror and window on each side of the vehicle, the 

driver-side mirror and driver-side window glance 

locations were impossible to distinguish from each 

other. 

46Note that due to the close proximity of the 

mirror and window on each side of the vehicle, the 

passenger-side mirror and passenger-side window 

glance locations were impossible to distinguish 

from each other. 

47Mazzae, E.N., Barickman, F.S., Baldwin, 

G.H.S., and Ranney, T.A. (2008). On-Road Study of 

Drivers’ Use of Rearview Video Systems 

(ORSDURVS). National Highway Traffic Safety 

Administration, DOT 811 024. 

TABLE 7—MEAN PERCENTAGE OF

TOTAL GLANCE TIME TO MIRROR

LOCATIONS FOR A BACKING MANEUVER WITH STAGED OBSTACLE

AVOIDANCE EVENT 44

Glance location 

Mean percentage of 

total glance 

time during 

a backing 

maneuver 

Driver-side Mirror/Driver-side 

Window 45 .............................. 15 

Interior Rearview Mirror ............ 5 

Passenger-side Mirror/Passenger-side Window 46 .......... 15 

NHTSA is currently engaged in 

research to examine the performance of 

these mirrors in displaying images of 

rear obstacles. While NHTSA has not 

yet conducted driving research with 

these mirrors we are planning to 

conduct research to examine drivers’ 

behavior and ability to avoid crashes 

with rear-mounted convex mirrors in 

2009. Upon completion, this mirror 

research will be summarized in a 

published NHTSA report. Along with 

comments received to this notice, 

NHTSA hopes to use this research 

information in the development of a 

proposal. 

B. Rearview Video Systems 

NHTSA has conducted and we are 

aware of some work conducted by GM 

that examined drivers’ use of rearview 

video based backing aids and their 

ability to use them to mitigate crashes. 

Below is a brief summary of this 

research. 

NHTSA Experimental Research: OnRoad Study of Drivers’ Use of Rearview 

Video Systems 

NHTSA conducted experimental 

research aimed to determine whether 

drivers look at the RV display during 

backing. While hardware performance 

testing has shown the rearview video 

systems can provide to the driver an 

image of any obstacles behind the 

vehicle in the RV system’s field of view, 

the driver must take the initiative to 

look at the display throughout the 

backing maneuver in order for the RV 

system to provide any benefit. The goal 

of this study was to further our 

understanding of the degree to which 

drivers may actively use RV systems 

while backing and whether the 

provision of such visual information 

will translate into decreased backing 

and backover incidents. 

This study also provided information 

useful in estimating the effectiveness of 

RV and supplemental sensors, in aiding 

drivers to avoid a backing crash. For 

example, the number of times per 

backing maneuver that a driver looked 

at the RV screen was tabulated. A driver 

that looks at the screen more often is 

more likely to notice when an obstacle 

appears. A look at the beginning of a 

backing maneuver is less likely to result 

in a driver’s detection of an obstacle 

than would frequent checking of the 

screen throughout the maneuver. 

Drivers’ use of rearview video systems 

was observed during staged and 

naturalistic backing maneuvers to 

determine whether drivers look at the 

RV display during backing and whether 

use of the system affects backing 

behavior.47 Thirty-seven test 

participants, aged 25 to 60 years, were 

comprised of twelve drivers of RVequipped vehicles, thirteen drivers of 

vehicles equipped with an RV system 

and a rear parking sensor system, and 

twelve drivers of vehicles with no 

backing aid system. All three system 

conditions were presented using 

original equipment configurations of the 

2007 Honda Odyssey minivan. All 

participants had driven and owned a 

2007 Honda Odyssey minivan as their 

primary vehicle for at least six months. 

Participants were not aware that the 

focus of the study was on their behavior 

and performance during backing 

maneuvers. 

Participants drove their own vehicles 

for a period of four weeks in their 

normal daily activities while backing 

maneuvers were recorded. At the end of 

four weeks, participants returned to the 

research lab to have the recording 

equipment removed. At the lab, the 

participants took a test drive in which 

an unexpected 36-inch-tall obstacle 

consisting of a two-dimensional 

photograph of a child appeared behind 

the vehicle during a final backing 

maneuver. Additional details of the test 

method are provided in Appendix B of 

this notice. 

The results of the naturalistic driving 

and unexpected obstacle scenario are 

provided below. 

Results for Naturalistic Driving 

• A total of 6,145 naturalistic backing 

maneuvers were recorded in the study, 

none of which resulted in a significant 

collision; however, some collisions (i.e., 

with trash receptacles and other parked 

vehicles) occurred during routine 

backing. 

• In the real-world backing situations, 

drivers equipped with RV systems spent 

8 to 12 percent of the time looking at the 

RV display during backing maneuvers. 

• On average, drivers made 2.17 

glances per backing maneuver with the 

RV-only system, and 1.65 glances per 

maneuver with the RV and sensor 

system. 

• Overall, drivers looked at least once 

at the RV display on approximately 65 

percent of backing events, and looked 

more than once at the RV display on 

approximately 40 percent of backing 

events. 

Results for Unexpected Obstacle 

Maneuver 

• Drivers with an RV system made 13 

to 14 percent of glances at the RV video 

display during the initial phase of 

backing in the staged maneuvers, 

independent of system presence. 

• Drivers spent over 25 percent of 

backing time looking over their right 

shoulder in the staged backing 

maneuvers. 

• Only participants who looked at the 

RV display more than once during the 

maneuver avoided a crash during the 

staged crash-imminent obstacle event. 

• Results indicated that the RV 

system was associated with a 

statistically significant (28 percent) 

reduction in crashes with the 

unexpected obstacle as compared to 

participants without an RV system. All 

participants in the ‘‘no system’’ 

condition crashed, since the staged 

obstacle event scenario was designed 

such that drivers without an RV system 

could not see the obstacle. 

Results of this study indicate that 

drivers looked at the RV display in 

approximately 14 percent of glances in 

baseline and obstacle events and 10 

percent of glances in naturalistic 

backing maneuvers. The agency 

recognized that the timing and 

frequency of drivers’ glances at the RV 

display has a noticeable impact on the 

likelihood of rear obstacle detection. 

However, making single or multiple 

glances at the RV display at the start of 

the maneuver does not ensure that the 

path behind the vehicle will remain 

clear for the entire backing maneuver. 

Overall, this study estimates that 

video-based backing systems would 

Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9495 

48Mazzae, E.N., Barickman, F.S., Baldwin, 

G.H.S., and Ranney, T.A. (2008). On-Road Study of 

Drivers’ Use of Rearview Video Systems 

(ORSDURVS). National Highway Traffic Safety 

Administration, DOT 811 024. 

49 Green, C. and Deering, R. (2006). Driver 

Performance Research Regarding Systems for Use 

While Backing. Society of Automotive Engineers, 

Paper No. 2006–01–1982. 

50McLaughlin, S.B., Hankey, J.M., Green, C.A., 

and Kiefer, R.J. (2003). Driver Performance 

Evaluation of Two Rear Parking Aids. Proceedings 

of the 2003 Enhanced Safety Vehicle Conference. 

51 Green, C. and Deering, R. (2006). Driver 

Performance Research Regarding Systems for Use 

While Backing. Society of Automotive Engineers, 

Paper No. 2006–01–1982. 

52 Green, C. and Deering, R. (2006). Driver 

Performance Research Regarding Systems for Use 

While Backing. Society of Automotive Engineers, 

Paper No. 2006–01–1982. 

53Mazzae, E.N., Barickman, F.S., Baldwin, 

G.H.S., and Ranney, T.A. (2008). On-Road Study of 

Drivers’ Use of Rearview Video Systems 

(ORSDURVS). National Highway Traffic Safety 

Administration, DOT 811 024. 

54 Green, C. and Deering, R. (2006). Driver 

Performance Research Regarding Systems for Use 

While Backing. Society of Automotive Engineers, 

Paper No. 2006–01–1982. 

mitigate approximately 28 to 42 percent 

of backover crashes 48. 

GM Experimental Research on Driver 

Performance Using Video-Based 

Backing Aid Systems 

GM conducted research to investigate 

ways to assist drivers in recognizing 

people or objects behind their vehicle 

while performing backing maneuvers.49

One study compared parking behaviors 

for rear camera and ultrasonic rear 

parking assist systems together, 

separately, and under traditional 

parking conditions (i.e., neither system). 

An obstacle was placed unexpectedly 

behind a driver’s vehicle prior to the 

start of a backing maneuver to assess the 

driver’s performance in obstacle 

detection and avoidance.50 Twenty-four 

participants struck the obstacle, while 

five participants avoided the obstacle. 

Of those participants who avoided the 

obstacle, three saw the obstacle while 

looking at the RV display (two in the RV 

system condition, one in the ultrasonic 

rear park assist and RV system 

condition), one saw the obstacle in their 

mirror (ultrasonic rear park assist and 

RV system condition), and one 

participant noticed the obstacle out of 

the back window (RV system condition). 

These results indicated that participants 

with an RV system were less likely to be 

involved in a backing incident. 

GM also sponsored a second research 

study to evaluate driver performance 

with rear camera systems.51 In this 

study, each participant parked their 

vehicle using a rear camera and 

ultrasonic system more than 30 times, 

including practice trials. During one 

scenario, participants, unaware that an 

experimenter placed an obstacle behind 

the vehicle, were asked to perform a 

backing maneuver to engage the 

ultrasonic rear park assist and the rear 

camera system. In some cases, a flashing 

symbol was employed in the 

approximate location of the rear 

obstacle as presented on the video 

display screen. While there were no 

statistically significant effects of either 

the symbol or the location of the 

obstacle, 65 percent of participants 

avoided the obstacle. Greater experience 

with the camera system and an 

increased number of trials presented 

that involved a ruse may have attributed 

to a higher object avoidance rate in this 

study than compared to the first study. 

Overall, GM’s research on rearview 

video systems suggested that RV 

systems may provide limited benefit in 

some backing scenarios.52

C. Sensor-Based Rear Object Detection 

Systems 

NHTSA and GM have both conducted 

research on drivers’ use of sensor-based 

backing aids and their ability to use 

them to mitigate crashes. Below is a 

brief summary of this research. 

NHTSA Experimental Research: Driver 

Performance With Rearview Video and 

Sensor-Based Rear Object Detection 

Systems 

NHTSA’s study of drivers’ use of 

rearview video systems (discussed in 

detail earlier in this document) also 

involved an observation of drivers of 

vehicles equipped with both an RV 

system and an ultrasonic-based rear 

parking sensor system. The rear parking 

sensor system tested detected the 

obstacle and provided a warning 

indication of the presence of a rear 

obstacle to the driver in 38 percent (5 

out of 13) of the event trials for 

participants with vehicles equipped 

with the combination system. Four of 

these 5 participants crashed into the 

obstacle. 

The test vehicle involved in the study 

had a control that allowed the driver to 

disable the parking sensor system. 

During the course of this study, half of 

the participants whose vehicles were 

equipped with a rear parking sensor 

system either stated or were observed to 

have turned the system off at least some 

of the time. Four participants made 

unsolicited comments to members of the 

research staff about turning off the rear 

parking sensor system on their 

vehicle.53 One of the four participants 

reported that he just did not use it. The 

three other participants stated that they 

frequently turned the rear parking 

sensor system off when driving through 

a restaurant drive-through lane due to 

nuisance alarms (i.e., audible 

notifications of the presence of vehicles 

that the driver is already aware of). A 

sixth participant did not comment on 

not using the system, but was observed 

having the rear parking sensor system 

on their vehicle switched off during 

their initial meeting visit. This tendency 

for some drivers to turn the rear parking 

sensor system off causes NHTSA to be 

concerned about the potential for this 

technology to be effective in mitigating 

backover incidents. 

GM Experimental Research on Driver 

Performance Using Sensor-Based 

Backing Aid Systems 

GM sponsored a study on the 

effectiveness of auditory backing 

warnings provided by a rear object 

detection system.54 The study found 

that only 13 percent of drivers avoided 

hitting an unexpected obstacle, and over 

87 percent of the drivers collided with 

the obstacle following the warning. 

Sixty-eight percent of drivers provided 

with the warning demonstrated 

precautionary behaviors in response to 

the warning, such as covering the brake 

with their foot, tapping the brake, or 

braking completely. While 44 percent of 

participants braked, these braking levels 

were generally insufficient to avoid a 

collision. Although data provides some 

evidence that warnings influenced 

driver behavior, warnings were 

unreliable in terms of their ability to 

induce drivers to immediately brake to 

a complete stop. 

This study further suggests that 

knowledge and experience with a 

backing warning system may not 

significantly improve immediate driver 

response to a backing warning. While 

specific training on the operation of the 

system was provided to eight drivers, 

only one avoided the obstacle. In each 

case, drivers reported that they did not 

expect to encounter an obstacle in their 

backing path. Many drivers also 

reported that they searched for an 

obstacle following the warning, but 

‘‘didn’t see anything’’ and continued 

their backing maneuver. These 

perceptions suggest that drivers’ 

expectations are important when 

seeking to influence driver behavior. 

NHTSA Experimental Research: Driver 

Performance With Sensor-Based Rear 

Object Detection Systems 

NHTSA is currently engaged in 

research to assess drivers’ ability to 

avoid backing crashes in a vehicle 

equipped with only a sensor-based rear 

object detection system. This work is 

scheduled to be completed in 2009 and 

9496 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

55Mazzae, E.N., Barickman, F.S., Baldwin, 

G.H.S., and Ranney, T.A. (2008). On-Road Study of 

Drivers’ Use of Rearview Video Systems 

(ORSDURVS). National Highway Traffic Safety 

Administration, DOT 811 024. 

56 General Motors (2006). Driver Performance 

Research Regarding Systems for Use While Backing. 

Society of Automotive Engineers, Paper No. 2006– 

01–1982. 

57Mazzae, E.N., Barickman, F.S., Baldwin, 

G.H.S., and Ranney, T.A. (2008). On-Road Study of 

Drivers’ Use of Rearview Video Systems 

(ORSDURVS). National Highway Traffic Safety 

Administration, DOT 811 024. 

58 Id. 

59 Id. 

60PRIA, section V. 

will be summarized in a published 

NHTSA report thereafter. Along with 

comments received to this notice, 

NHTSA hopes to use this research 

information in the development of a 

proposal. 

D. Multi-Technology (Sensor + Camera) 

Systems 

NHTSA has not conducted research 

examining drivers’ use of any 

integrated, multi-technology systems 

designed to aid drivers in performing 

backing maneuvers. However, NHTSA’s 

study of drivers’ use of rearview video 

systems (discussed in detail earlier in 

this document) involved an observation 

of drivers of vehicles equipped with 

both an RV system and an ultrasonicbased rear parking sensor system that 

functioned independently. Data from 

this study indicated that equipping a 

vehicle with a rear object detection 

system and an RV system that are not 

integrated resulted in lesser backing 

crash avoidance effectiveness than 

attainable with RV alone. Although 

statistically not significant due to the 

relatively small number of test 

participants, more participants with 

vehicles equipped with both an RV and 

a rear parking sensor system (85 

percent) crashed into an obstacle than 

did those (58 percent) driving vehicles 

equipped with only an RV system. 

However, the fact that the rear parking 

sensor system only detected the obstacle 

in 38 percent of test trials may help 

explain the result if the drivers relied on 

the sensor system first. NHTSA’s 

research on the performance of 

currently available sensor-based systems 

in detecting rear obstacles has shown 

their performance to be inconsistent, 

particularly in the detection of small 

children. It is possible that those 

performance deficits for sensor-based 

rear object detection systems could have 

a negative impact on the overall 

effectiveness of RV systems, particularly 

if drivers rely on the sensor system’s 

auditory alerts to cue them to look at the 

RV display. 

During our study, drivers of the 

vehicles with RV and sensors looked at 

the RV system visual display less 

frequently than did drivers of the same 

vehicle equipped with only the RV 

system. NHTSA seeks comment on 

whether there is research that would 

indicate why this would occur or if 

others have found a similar trend. 

E. Summary 

Table 8 presents a summary of the 

estimated effectiveness information for 

systems that may aid in the mitigation 

of backover incidents that NHTSA has 

collected to date. Estimates for system 

performance in detecting rear obstacles 

and overall effectiveness based on 

driver use are listed separately. System 

performance for rearview video systems 

was assumed to be 100 percent, since 

these systems have the capability to 

show any object within their field of 

view. System performance for sensorbased systems is based on object 

detection rates seen in the obstacle 

avoidance event presented in the study 

of drivers’ use of rearview video 

systems.55 Overall effectiveness values 

for rearview video systems alone and 

combined with a rear parking sensor 

system are based on results of NHTSA’s 

study of drivers’ use of rearview video 

systems. The value for rear parking 

sensor systems is calculated based on a 

combination of the 39 percent object 

detection rate from the study of drivers’ 

use of rearview video systems and 

additional data that NHTSA has 

collected. We note that GM’s study of 

drivers’ use of backing warning systems 

found that only 13 percent of drivers 

were able to avoid a crash with a rear 

obstacle in a staged scenario using a rear 

parking sensor system.56

TABLE 8—ESTIMATED SYSTEM PERFORMANCE AND OVERALL EFFECTIVENESS

Countermeasure System performance in object detection— 

percent detections 

Percent overall effectiveness 

(technology + driver) 

Rear-Mounted Convex Mirrors .......................... (Research underway) ....................................... (Research underway). 

Rearview Video ................................................. 100 .................................................................... 42 57. 

Rearview Video + Sensors ................................ 100 .................................................................... 15 58. 

Sensors .............................................................. 39 59 .................................................................. 17.66 60 (estimate). 

F. Questions 

(1) NHTSA has not conducted 

research to estimate a drivers’ ability to 

avoid crashes with a backing crash 

countermeasure system based only on 

sensor technology. We request any 

available data documenting the 

effectiveness of backing crash 

countermeasure systems based only on 

sensor technology in aiding drivers in 

mitigating backing crashes. 

(2) NHTSA has not conducted 

research to estimate drivers’ ability to 

avoid crashes with a backing crash 

countermeasure system based on 

multiple, integrated technologies (e.g., 

rear parking sensors and rearview video 

functions in one integrated system). We 

request any available objective data 

documenting the effectiveness of multitechnology backing crash 

countermeasure systems in mitigating 

backing crashes. We also request 

comment on what types of technology 

combinations industry may consider 

feasible for use in improving rear 

visibility. 

(3) NHTSA requests any available 

data documenting the image quality of 

rear-mounted convex mirrors and their 

effectiveness in aiding drivers in 

preventing backing crashes. 

(4) NHTSA requests any available 

additional objective research data 

documenting the effectiveness of sensorbased, rearview video, mirror, or 

combination systems that may aid in 

mitigating backover incidents. 

(5) NHTSA requests information 

regarding mounting limitations for rearmounted convex mirrors. 

VII. Rear Visibility of Current Vehicles 

The degree of direct rear visibility 

(i.e., what a driver can directly see with 

or without the aid of non-required 

mirrors or other devices) in a particular 

vehicle depends on a number of factors, 

including the driver’s size and various 

aspects of the vehicle’s design, such as 

the width of a vehicle’s structural pillars 

(i.e., B and C pillars) and the size of its 

window openings. Rear seat head 

restraints can also affect direct rear 

Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9497 

61Note that 49 CFR Sec. 571.111 Standard No. 

111, Rearview mirrors, Section 5.1.1 states that 

‘‘The line of sight may be partially obscured by 

seated occupants or by head restraints.’’ 62Mazzae, E.N., Garrott, W.R. (2008). Light 

Vehicle Rear Visibility Assessment. National 

Highway Traffic Safety Administration, DOT 810 

909. 63Measured vehicles included the ten top-selling 

passenger cars and light trucks for calendar year 

2006. 

visibility.61 Additionally, due to their 

geometries and the position of a driver’s 

eyes with respect to the bottom of the 

rear window (or top edge of a pickup 

truck’s tailgate), vehicles with greater 

overall height and length are likely to 

have larger rear blind zone areas than 

shorter vehicles. 

To assess a vehicle’s rear visibility 

and how it varies from vehicle to 

vehicle, in 2007,62 NHTSA measured 

the rear visibility characteristics of 44 

recent-model light vehicles.63 NHTSA’s 

measurements involved assessment of 

the visibility of a visual target over an 

area stretching 35 feet to either side of 

the vehicle’s centerline, 90 feet back 

from the vehicle’s rear bumper, and 20 

feet forward of the rear bumper. Rear 

visibility metrics were calculated using 

a subset of this area measuring 60 feet 

wide by 50 feet long (3000 square feet). 

The agency selected a 29.4-inch-tall 

visual target representing the 

approximate height of a 1-year-old child 

and the youngest walking potential 

backover victims. Rear visibility was 

measured for both a 50th percentile 

adult male driver (69.1 inches tall) and 

a 5th percentile adult female driver 

(59.8 inches tall). The areas over which 

the visual target was visually 

discernible using direct glances (i.e., 

looking out vehicle windows) and 

indirect glances (i.e., looking into side 

or interior rearview mirrors) were 

determined. 

While NHTSA measured the area 

indirectly visible to the driver in the 

side and interior rearview mirrors, we 

focused our assessment on direct rear 

visibility in order to assess the degree to 

which the vehicle’s structure affects 

what a driver can see out the vehicle’s 

windows. This permitted an assessment 

of how rear visibility is affected by a 

vehicle’s structure and allowed for 

better vehicle comparison since this 

metric varied more than would rear 

visibility measured using both direct 

vision and indirect vision devices 

together. In other words, considering 

both direct and indirect rear visibility 

together would allow less room for 

distinguishing between the qualities of 

rear visibility amongst vehicles. 

Examples of the measured direct fields 

of view for four common vehicles types 

are shown in Figures 5–8. 

BILLING CODE 4910–59–P 

9498 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 


EP04MR09.004</GPH>
Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9499 


EP04MR09.005</GPH>
9500 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 


EP04MR09.006</GPH>
Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9501 

64 ‘‘Rear blind zone area’’ is defined here to mean 

the area in square feet within a 50-foot wide by 60- 

foot long area and at ground level over which a 

29.4-inch-tall object is visible using direct vision. 

BILLING CODE 4910–59–C 

Through this study, NHTSA estimated 

that rear blind zone areas 64 for 

individual vehicles ranged from 

approximately 100 to 1,440 square feet 

over the 3,000 square-foot measurement 

area. When summarized by vehicle 

category and curb weight (as a surrogate 

indicator for vehicle size), as illustrated 

in Figure 9, the data shows that average 

direct-view rear blind zone areas varied 

within these groups. The greatest range 

of direct-view rear blind zone area size 

was seen for the 4,000–5,000 lb SUV 

group. Figure 10 illustrates that SUVs 

(as a whole) were associated with the 

largest average direct-view rear blind 

zone area as well as the largest range of 

values for the four body types 

examined. Overall, LTVs (vans, pickups, 

and SUVs) as a vehicle class were 

observed to have larger rear blind zone 

areas than passenger cars, as indicated 

in Figure 10. 


EP04MR09.007</GPH>
9502 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

For all 44 vehicles, NHTSA also 

measured the distance behind the 

vehicle at which the visual target could 

first be seen, i.e., the direct-view rear 

longitudinal sight distance. Average 

direct-view rear longitudinal sight 

distances were determined by 

mathematically averaging eight 

longitudinal sight distance 

measurements taken in 1-foot 

increments across the rear of each 

vehicle. As illustrated in Figure 11, 

LTVs generally had longer rear 

longitudinal sight distances than 

passenger cars. Exceptions to this trend 

included a few small pickup trucks for 

which average direct-view rear sight 

distance values were in the vicinity of 

those measured for smaller passenger 

cars, as shown in Figure 12. Average 

direct-view rear sight distance values 


EP04MR09.008</GPH> EP04MR09.009</GPH>
Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9503 

were longest for a full-size van, SUVs and pickup trucks with a curb weight of 

4,000 lbs or greater. 


EP04MR09.010</GPH> EP04MR09.011</GPH>
9504 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

65Mazzae, E.N., Garrott, W.R. (2008). Light 

Vehicle Rear Visibility Assessment. National 

Highway Traffic Safety Administration, DOT 810 

909. 

66Partyka, S., Direct-View Rear Visibility and 

Backing Risk for Light Passenger Vehicles (2008). 

67This area was chosen because it was the largest 

available measurement area for the facility in which 

these measurements were conducted. 

68The 50 feet long by 20 feet wide test area was 

examined to assess how much of the area behind 

the vehicle was critical to consider for rear visibility 

in relation to the prevention of backover incidents. 

69The states provide annual files of their policereported data under voluntary agreements with 

NHTSA. These are collected by the National Center 

for Statistics and Analysis, Office of Data 

Acquisition. The data are available for agency use. 

Public release of any of the files requires written 

approval from the individual state. 

70A simple correlation measures the strength of 

the statistical relationship between two variables. 

For example, one can graph two variables (such as 

the real-world risk of being involved in a backing 

crash as a function of laboratory measures of rear 

visibility) as a scatter plot. A simple correlation 

analysis measures how closely the plot resembles 

a line. If the plot suggests a line, then we might 

conclude that the laboratory measures are useful in 

predicting real-world involvements. However, it is 

difficult to use this approach if one suspects that 

there are complicating (confounding) factors that 

affect the simple comparison between two 

variables. 

71 r=0.51, p=0.02. 

72 r=0.26. 

73A logistic analysis allows us to account for 

complicating factors (such as systematic differences 

in how vehicles are used and by whom) by 

including them in a statistical model. This model 

predicts the risk of a crash being a backing crash 

as a function the laboratory measures of rear 

visibility after removing (controlling for) the effects 

of measurable complicating factors. 

74Partyka, S., Direct-View Rear Visibility and 

Backing Risk for Light Passenger Vehicles (2008). 

75Additional details on how a rear blind zone 

area based threshold might be developed are in 

Appendix D. 

Overall, our direct-view rear visibility 

measurements indicated that LTVs 

measured in this study exhibited worse 

rear visibility when compared with 

passenger cars, but there was overlap 

amongst all vehicle categories. 

VIII. Relationship Between Rear 

Visibility and Backing/Backover 

Crashes 

Using the direct-view rear blind zone 

area and longitudinal sight distance 

measurements 65 discussed in the prior 

section, NHTSA investigated whether a 

statistical relationship could be 

identified between these metrics and all 

backing crashes, as well as backover 

crashes (i.e., the subset of backing 

crashes involving a pedestrian or 

bicyclist being struck by a backing 

vehicle).66 NHTSA assessed the 

relationship between real world 

backing/backover crashes and rear 

visibility based on three metrics: 

average rear longitudinal sight distance, 

direct-view rear visibility measurements 

for a 50 feet long by 60 feet wide 67 test 

area, and direct-view rear visibility for 

a 50 feet long by 20 feet wide 68 test 

area. 

Backing risk was estimated from 

police-reported crashes in the State Data 

System.69 To calculate risk, backing 

rates were derived for 21 vehicle groups 

with vehicles that had at least 25 

backing crashes to account for statistical 

variability. Backing rate data were 

provided by the following states for the 

specified calendar years: 

• Alabama (2000–2003) 

• Florida (2000–2005) 

• Georgia (2000–2005) 

• Illinois (2000–2005) 

• Kansas (2001–2006) 

• Kentucky (2000–2005) 

• Maryland (2000–2005) 

• Michigan (2004–2006) 

• Missouri (2000–2005) 

• Nebraska (2000–2004) 

• New Mexico (2001–2006) 

• New York (2000) 

• North Carolina (2000–2005) 

• Pennsylvania (2000–2001, 2003– 

2005) 

• Utah (2000–2004) 

• Washington (2002–2005) 

• Wisconsin (2000–2005) 

• Wyoming (2000–2005) 

Simple correlation analysis 70

revealed an association between directview rear blind zone area and backing 

crash risk. Specifically, larger blind 

zone areas tended to be associated with 

a greater risk of being involved in a 

backing crash. A statistically significant 

relationship 71 between backing crash 

risk and direct-view rear blind zone area 

was discovered for both test areas, 

suggesting that this metric is a sensitive 

predictor of backing crash risk. 

However, in this analysis, the 

association between average rear 

longitudinal sight distance and backing 

risk was found to be weaker and not 

statistically significant due to the 

relatively small number of backover 

incidents, suggesting that this metric is 

not a sensitive predictor of backing 

crash risk.72

Logistic analysis 73 for the risk of a 

backover incident produced results that 

approached statistical significance for 

the rear blind zone area metrics, with a 

similar trend and magnitude as those for 

all backing crashes. Vehicles with the 

largest blind zone areas had 2–3 times 

the risk of a backover incident than 

those vehicles with the smallest blind 

zone areas.74 Conversely, estimated 

results for the risk of backover using 

rear longitudinal sight distance were not 

statistically significant. 

IX. Options for Mitigating Backover 

Incidents 

Using rear blind zone area as a metric, 

NHTSA’s research seems to indicate 

that there is a range of performance 

amongst vehicles and that LTVs on 

average had worse rear visibility than 

passenger cars. NHTSA also found a 

statistically significant correlation 

between rear blind zone area and 

backing crashes. Finally, our crash data 

appear to indicate that LTVs are 

overrepresented in backing and 

backover crashes. Based on these 

findings, NHTSA has identified 

potential approaches to improve rear 

visibility and to address the backing and 

backover crash risks for passenger 

vehicles. 

A. Approaches for Improving Vehicles’ 

Rear Visibility 

One approach would be to eliminate 

all rear blind zones by requiring that all 

vehicles have a rear blind zone size of 

0 sq. ft. (i.e., no rear blind zone). Such 

a requirement would be met by a 

visibility enhancement countermeasure 

that allowed the driver to see or 

otherwise determine that a pedestrian is 

in a specified zone behind the vehicle. 

This strategy would improve rear 

visibility for all vehicles. 

Alternatively, NHTSA could specify 

that all LTVs as a vehicle class have no 

rear blind zone since our crash data 

indicated that this vehicle category 

seems to be overrepresented in backing 

and backover crashes. This alternative 

would target the class of vehicles which 

are disproportionately responsible for 

the largest portion of backover fatalities. 

Another approach would be to 

establish a maximum rear blind zone 

area limit (based on crash rate) that all 

vehicles, or LTVs as a vehicle class, 

would have to meet.75 The threshold 

would be applied to all vehicles, such 

that any vehicle not meeting the 

minimum rear visibility threshold 

would be required to be equipped with 

a rear visibility countermeasure. 

Because styling engineers would have a 

target threshold giving them an idea of 

minimum ‘‘acceptable’’ rear visibility, 

such an approach would allow 

manufacturers the flexibility to consider 

and improve those attributes of a 

vehicle that contribute to rear visibility 

since they would have the option of not 

having to provide a rear visibility 

enhancement countermeasure. 

Depending on how high or low the 

threshold was set, for example, the 

agency could focus countermeasure 

application on vehicles with the largest 

rear blind zone areas and those vehicles 

Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9505 

76This sales figure represents 2007 vehicle sales. 

For the subsequent NPRM, updated sales figures 

will be used. 

77To illustrate this approach, this example 

scenario assumes that 25 percent of passenger cars 

will not comply with the rear visibility threshold. 

78To illustrate this approach, this example 

scenario assumes that 75 percent of LTVs and 25 

percent of passenger cars will not comply with the 

rear visibility threshold. 

79Cost calculations presented in Table 9 assume 

a 3 percent discount rate. Values also consider 

ranges of effectiveness for the technologies listed. 

Additional details regarding these calculations can 

be found in the PRIA. 

80Mazzae, E.N., Barickman, F.S., Baldwin, 

G.H.S., and Ranney, T.A. (2008). On-Road Study of 

Drivers’ Use of Rearview Video Systems 

(ORSDURVS). National Highway Traffic Safety 

Administration, DOT 811 024. 

that are most involved in backing and 

backover crashes. 

Using these approaches, NHTSA 

offers our preliminary information 

regarding the benefits and costs of 

various scenarios. 

B. Cost Benefit Scenarios 

For the relevant technologies, we have 

generated estimates using two different 

types of video cameras available in the 

market today and two different types of 

object detection sensors. For rearview 

video systems, some manufacturers are 

using cameras with a 130-degree field of 

view while others are using ones with 

a 180-degree field of view. These are 

noted as ‘‘130 ° Camera’’ and ‘‘180 ° 

Camera,’’ respectively. Note that these 

angular values are camera specifications 

and indicate the angle of view with 

respect to the center of the camera lens 

and not the center of the rear of the 

vehicle. Due to styling issues, cameras 

on some vehicle models may be 

mounted off-center and, as a result, their 

fields of view may not be symmetrical 

with respect to the center of the 

vehicle’s rear bumper. The sensor 

technologies included in the estimates 

are ultrasonic and radar. It should be 

noted that given our lack of information 

regarding the effectiveness of mirrors, 

we could not generate a cost benefit 

scenario using this technology. 

Using various scenarios, NHTSA has 

developed preliminary estimates of the 

costs and benefits for improving rear 

visibility assuming 16.6 million (8.5 

million LTVs and 8.1 million passenger 

cars) total vehicles.76 One scenario 

involves the application of a rear 

visibility countermeasure to all vehicles 

and a second assumes that a 

countermeasure is applied to all LTVs 

and no passenger vehicles. Given that a 

rear visibility threshold has not yet been 

established and that NHTSA has not 

measured all vehicle models sold in the 

U.S. to determine their rear blind zone 

areas, two additional, hypothetical 

scenarios were considered. One scenario 

assumes that a rear visibility 

countermeasure would be required for 

all LTVs and any passenger cars that do 

not comply with the rear visibility 

threshold (hypothetically assumed to 

encompass 25 percent of vehicles).77

Another scenario assumes that a rear 

visibility countermeasure would be 

required for any light vehicle that does 

not comply with the rear visibility 

threshold (hypothetically assumed to 

encompass 75 percent of LTVs and 25 

percent of passenger cars).78 Table 9 

presents the overall range of costs and 

benefits across these four scenarios. 

TABLE 9—PRELIMINARY BENEFITS AND COSTS ESTIMATES—ACROSS FOUR COUNTERMEASURE APPLICATION

SCENARIOS 79

Countermeasure technology options 

Net cost 

(does not consider 

vehicles already 

equipped with RV) 

(in $M) 

Cost per life 

saved 

(in $M) 

Total fatalities 

avoided 

Total injuries 

avoided 

RV with 130 ° Camera and Interior Mirror Display .................. $1,153–$2,577 $16.17–$57.27 26–69 1,279–5,189 

RV with 130 ° Camera and In-Dash Display ........................... 981–2,294 15.69–56.41 26–69 1,279–5,189 

RV with 180 ° Camera and Interior Mirror Display .................. 1,325–3,005 13.76–50.99 31–82 1,689–6,141 

RV with 180 ° Camera and In-Dash Display ........................... 1,234–2,811 14.61–52.76 31–82 1,689–6,141 

Ultrasonic Rear Object Detection System ............................... 277–766 11.25–33.84 5–24 399–1,793 

Radar Rear Object Detection System ..................................... 571–1,397 21.02–49.84 6–26 479–1,976 

Rear-mounted Convex Mirrors ................................................ (Research in progress) 

Additional details regarding these 

calculations can be found in the 

preliminary regulatory impact analysis 

document, ‘‘Rear Visibility 

Technologies: FMVSS No. 111.’’ 

NHTSA will continue to gather 

information on price and vehicle 

equipment trends for use in refining 

these estimates of costs and benefits for 

improving rear visibility. 

C. Questions 

NHTSA requests comments on 

benefits and costs for rear visibility 

enhancement countermeasures and the 

possibility of developing a rear blind 

zone area based minimum acceptable 

rear visibility threshold. Specific 

questions are as follows: 

(1) NHTSA seeks comment on the 

areas behind a vehicle that may be most 

important to consider when improving 

rear visibility. Furthermore, while the 

distribution of visible area behind the 

vehicle was not considered in the blind 

zone area metrics (e.g., rear blind zone 

area) discussed in this document, it may 

be helpful to specify some specific areas 

behind the vehicle that must be visible. 

(2) NHTSA invites comment as to 

how an actual threshold based on 

vehicles’ rear blind zone area could be 

defined. 

(3) For vehicles whose rear visibility 

does not meet a required minimum 

threshold and thus require a 

countermeasure, OEMs may decide to 

further alter the styling of the rear of the 

vehicle to the detriment of direct rear 

visibility (e.g., making the rear window 

a tiny, circular porthole). Based on the 

fact that NHTSA’s research 80 showed 

that drivers of RV-equipped vehicles 

glanced at least one time at the RV 

display in only 65 percent of backing 

maneuvers, maintaining good direct rear 

visibility may be important for the other 

35 percent of cases in which the RV 

system is not used. Therefore, NHTSA 

is considering specifying a minimum 

portion of a vehicle’s rear visibility that 

must be provided via direct vision (i.e., 

without the use of mirrors or other 

indirect vision device). NHTSA seeks 

comments on this approach, such as 

input regarding how a minimum 

threshold should be specified, and how 

much of a vehicle’s rear area should be 

visible via direct vision? 

9506 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

81SAE J1050, Describing and Measuring the 

Driver’s Field of View; Revised 2003–01. 

82Note: NHTSA has not evaluated the 

engineering drawings or three-dimensional 

computer models of manufactured vehicles, on 

which this method appears to rely. 

83Paine, M., Macbeth, A., and Henderson, M. 

(2003). The Danger to Young Pedestrians from 

Reversing Motor Vehicles. 18th International 

Technical Conference on the Enhanced Safety of 

Vehicles. Paper Number 466. 

84Consumer Reports (August, 2006). Blind-zone 

measurements. http://www.consumerreports.org/ 

cro/cars/safety-recalls/mind-that-blind-spot-1005/ 

blindspot-measurements/index.htm. 

85The heights of the subject drivers were 68 

inches (approximate height for a 50th percentile 

adult male) and 61 inches (approximate height for 

a 5th percentile small female). 

(4) NHTSA requests information 

regarding anticipated costs for rear 

visibility enhancement 

countermeasures. 

(5) Given the increasing popularity of 

LCD panel televisions and likely 

resulting price decline, what decline in 

price can be anticipated for LCD 

displays used with rearview video 

systems? Will similar price reduction 

trends be seen for video cameras for 

rearview video system application? 

(6) NHTSA requests information on 

the estimated price of rear visibility 

enhancement countermeasures at higher 

sales volumes, as well as the basis for 

such estimates. 

(7) NHTSA requests any available 

data on rearview video system 

maintenance frequency rates and 

replacement costs. How often are 

rearview video cameras damaged in the 

field? 

(8) NHTSA requests comments on 

which types of possible rear visibility 

enhancement countermeasure 

technologies may be considered for use 

on which types of vehicles. This 

information is important for estimating 

the costs of countermeasure 

implementation in the fleet. 

(9) NHTSA requests information 

regarding available studies or data 

indicating the effectiveness of 

dashboard display-based rearview video 

systems and rearview mirror based 

rearview video systems. What are the 

key areas that will impact the real-world 

effectiveness of these systems as they 

become more common in the fleet? 

(10) NHTSA requests objective data 

on the use, effectiveness, and cost of 

rear-mounted convex mirrors. 

X. Options for Measuring a Vehicle’s 

Rear Visibility 

If a maximum rear blind zone area 

limit threshold is used to establish the 

need for a vehicle to be equipped with 

a countermeasure, its rear visibility 

characteristics would need to be 

measured and that vehicle’s direct-view 

rear visibility and rear blind zone areas 

would need to be calculated. As such, 

if the agency chooses to establish a 

threshold value for minimum 

performance, a test procedure would 

need to be developed. In this section, 

the agency identifies those test 

procedures it has identified that could 

be used for this purpose. The 

advantages and disadvantages of the 

different identified methods are also 

discussed. 

A. Rear Visibility Measurement 

Procedures 

Society of Automotive Engineers 

The Society of Automotive Engineers 

(SAE) 81 has created a recommended 

practice for determining the areas 

around a vehicle that a driver can see 

through direct vision (i.e., without the 

use of mirrors or another indirect vision 

device). This procedure uses computerbased simulations to describe rear 

visibility for a particular vehicle. Using 

standard driver eye points and a threedimensional computer model of the 

vehicle, the simulation allows the 

rotation of sight lines originating from 

the eye points to determine the areas 

that the driver should be able to see 

outside the vehicle.82 This approach to 

determine a vehicle’s visibility 

characteristics is theoretical and has not 

been assessed for reproducibility and 

repeatability against actual vehicles. 

Paine, Macbeth & Henderson 

In 2003, Paine, Macbeth & Henderson 

described a method to approximate a 

driver’s sight line using an H-point 

machine and laser pointing device. 

Using the data, a ‘‘visibility index’’ was 

calculated to highlight the researchers’ 

belief that vehicle design plays a major 

role in the rear visibility of vehicles. 

This study, sponsored by the 

Insurance Australia Group, was 

designed to be easily repeatable and 

standardized to enable accurate 

comparisons between vehicles.83 The 

laser device was mounted to the side of 

the H-point machine’s head fixture in 

the approximate vicinity of where a 

driver’s head would be located. A 

dimensioned grid was positioned 

behind the test vehicle and a test target 

consisting of a cylinder 600 mm (24 in.) 

tall and 200 mm (7.87 in.) in diameter 

was used. Additionally, the driver’s seat 

was placed in its lowest and furthest 

back position and adjusted to ensure 

that the rear of the H-point device was 

placed at a 25 degree angle. 

Data from this test procedure were 

used to calculate vehicle ratings by 

considering several factors including the 

total visible area behind the vehicle; the 

visible distance across the rear of the 

vehicle; and the presence of backing 

aids such as proximity sensors and 

rearview camera systems. Consequently, 

the authors identified several vehicle 

design aspects that affect rear visibility, 

including a high bootlid (referred to as 

the ‘‘trunk lid’’ in the US); rear-mounted 

spare tires; rear head restraints; center 

high-mounted brake lights; rear 

mounted wipers; and rear spoilers. 

NHTSA believes the rear visibility 

assessment method outlined by these 

researchers has merit. However, further 

refinement may be desirable. For 

instance, a more accurate eye point for 

location of the laser beam would better 

simulate what a 50th percentile male 

would be able to see. The agency is 

undertaking research to examine the use 

of laser-based methods of measuring a 

vehicle’s rear visibility characteristics. 

Consumer Reports Linear Rear Blind 

Spot Measurement Method 

Consumer Reports evaluates vehicles 

for rear visibility and publishes the 

findings as part of their new vehicle 

reviews. In their August 2006 report, 

they examined vehicles to determine the 

closest distance at which a 28-inch 

object (approximating the height of a 

child less than 1 year old) could be 

detected behind a vehicle.84 During the 

evaluation, drivers 85 were seated in the 

vehicle and asked to detect an object 

while it was moved outward from the 

rear of the vehicle along its centerline. 

The distance from the rear bumper at 

which the driver could detect the object 

was measured, and then these sight 

distances were published as consumer 

information. 

Consumer Reports’ data describe a 

rear sight distance as measured at the 

centerline of the vehicle, which may not 

accurately describe rear visibility across 

the entire width of the rear of the 

vehicle and therefore not fully address 

the risk of a backing crash. In addition, 

the use of human drivers, particularly a 

single driver of a particular height, to 

estimate rear visibility for a vehicle is 

likely to produce results that are subject 

to variability stemming from individual 

differences. While this information may 

be helpful to consumers, for the 

purposes of establishing a Federal 

regulation on rear visibility, NHTSA 

would be required to follow an 

approach that has demonstrated 

objectivity and repeatability. 

Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9507 

86Mazzae, E.N., Light Vehicle Rear Visibility 

Assessment, DOT HS 810 909, September 2008. 

NHTSA’s visual target for this test was a traffic cone 

with a reflector atop; its height is representative of 

a 1-year-old child. 87See also Consumer Reports (August, 2006). 

Blind-zone measurements. http:// 

www.consumerreports.org/cro/cars/safety-recalls/ 

mind-that-blind-spot-1005/blindspotmeasurements/index.htm. Accessed 3/1/2006. 88See also Paine, M., Macbeth, A., and 

Henderson, M. (2003). The Danger to Young 

Pedestrians from Reversing Motor Vehicles. 18th 

International Technical Conference on the 

Enhanced Safety of Vehicles. Paper Number 466. 89Note that when a driver wearing eye glasses 

turns to look over their right shoulder to see behind 

their vehicle, there is a point at which the line of 

sight can pass beyond the perimeter of the lens, at 

which point the driver loses the aid of the 

corrective lens. 

90Paine, M., Macbeth, A., and Henderson, M. 

(2003). The Danger to Young Pedestrians from 

Reversing Motor Vehicles. 18th International 

Technical Conference on the Enhanced Safety of 

Vehicles. Paper Number 466. 

91 Id. 

92 ISO 7397–2, Passenger cars—Verification of 

driver’s direct field of view—Part 2: Test method, 

first edition, 1993–07–01. 

93Partyka, S., Direct-View Rear Visibility and 

Backing Risk for Light Passenger Vehicles, (2008). 

94Mazzae, E.N., Light Vehicle Rear Visibility 

Assessment, DOT HS 810 909, September 2008. 

NHTSA’s visual target for this test was a traffic cone 

with a reflector atop; its height is representative of 

a 1-year-old child. 

NHTSA’s Human-Based Rear Visibility 

Measurements 

In 2007, NHTSA measured the rear 

visibility characteristics of 44 vehicles 

using human drivers to report the actual 

area around a vehicle where they could 

detect a 29.4-inch-tall test object.86

During the test procedure, the visual 

target was moved behind the vehicle 

over a grid of 1-foot squares spanning 

110 feet longitudinally (including 90 

feet behind the vehicle’s rear bumper) 

and 70 feet laterally (i.e., 35 feet to 

either side of the vehicle’s centerline). 

Points on the grid where the entire 3- 

inch reflector (comprising the top 

portion of the test object) was visible 

were recorded and combined to produce 

a graphical rear field of view 

representation for the vehicle. Visible 

areas around the vehicle were assessed 

for a 50th percentile male and 5th 

percentile female driver. These driver 

sizes were chosen to acquire a range of 

visibility data in relation to driver 

height and because they have been used 

by other organizations 87 88 in similar 

visibility tests. 

NHTSA observed that physical 

characteristics among drivers can affect 

rear visibility. These characteristics 

include the occupant’s torso breadth, 

physical flexibility (e.g., torso and neck 

rotational range), peripheral visual 

ability, visual acuity, and the presence 

of eye glasses.89 Additional differences 

relating to driver positioning while 

backing (e.g., raising the body up from 

the seat pan to achieve a higher vantage 

point), driver preferences regarding seat 

adjustment, and mirror positioning may 

also affect rear visibility. For example, 

based on a review of test data, it appears 

that the particular 5th percentile female 

driver involved in this testing may have 

been less restricted in her body 

movement (i.e., leaned or ‘‘craned’’ 

body more) when attempting to view the 

visual target. This resulted in a situation 

that for some vehicles, the measured 

minimum sight distance and average 

sight distance values were better for the 

shorter driver than for the taller driver. 

NHTSA’s Laser-Based Rear Visibility 

Measurement Procedure 

NHTSA’s rear visibility research 

conducted in 2008 began with an effort 

to improve upon the previously used 

human-based rear visibility 

measurement procedure. Since any 

compliance test for the Federal motor 

vehicle safety standards is required by 

law to be repeatable and reproducible, 

enhancements were focused on 

improving this aspect of the 

measurement procedure. The agency 

considered known rear visibility 

measurement procedures, built upon the 

work by Paine et al.,90 and developed an 

enhanced version of that procedure that 

replaced the human driver previously 

used in rear visibility measurements 

with a laser-based fixture. The enhanced 

procedure approximated the direct rear 

visibility of a vehicle for a 50th 

percentile male driver using a fixture 

that incorporated two laser pointing 

devices to simulate a driver’s line of 

sight. One laser pointing device was 

positioned at the midpoint of a 50th 

percentile male’s eyes when looking 

rearward over his left shoulder and the 

other device was placed at the midpoint 

of a 50th percentile male’s eyes when 

looking rearward over his right shoulder 

during backing. 

The use of a laser pointing device to 

simulate driver sight line was also used 

by Paine, et al.91 However, they used 

only a single eye point that was 

approximately at the side of a 50th 

percentile male driver’s head. In 

addition, ISO 7397–2,92 which outlines 

a procedure for verifying the driver’s 

180-degree forward direct field of view 

for passenger cars, also uses a laserbased measurement technique. The use 

of two representative eye points and a 

wider measurement area have been 

proven to correlate well with backing 

crash risk 93 and therefore may result in 

a more valid measurement method. 

More details of NHTSA’s revised rear 

visibility measurement procedure using 

lasers are provided below. 

1. Size of Rear Visibility Measurement 

Field 

The size of the field over which rear 

visibility is measured should encompass 

those areas critical to the avoidance of 

backover crashes. To evaluate the 

dimensions of this field, NHTSA 

measured rear blind zone area data for 

a variety of vehicles and compared these 

results with backing crash data for those 

vehicles. In addition, a Monte Carlo 

simulation analysis of relative backing 

crash risk as a function of pedestrian 

location was performed. The results of 

these analyses are summarized below. 

Data analysis was performed to assess 

the correlation between vehicles’ rear 

blind zone areas measured using a 50th 

percentile male driver and the backing 

crash data for 21 vehicles.94 Results of 

this analysis for a portion of the field 

sizes assessed are summarized in Table 

10 (Appendix D contains a table 

summarizing the complete set of areas 

assessed). Evidence of good correlation 

in this analysis is given by high 

correlation coefficient values and a low 

probability of occurrence by chance. All 

measurement field dimension 

combinations listed in Table 10 show 

good correlation with backing crashes. 

A similar preliminary analysis recently 

conducted by NHTSA using laser-based 

rear blind zone areas measured for 60 

vehicles over various measurement field 

sizes showed a 50 feet square field to be 

better correlated with backing crashes 

than narrower field size of the same 

longitudinal dimension. 

9508 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

95SAE J826, Devices for Use in Defining and 

Measuring Vehicle Seating Accommodation, Rev. 

JUL95. 

96See also Consumer Reports (August, 2006). 

Blind-zone measurements. http:// 

www.consumerreports.org/cro/cars/safety-recalls/ 

mind-that-blind-spot-1005/blindspotmeasurements/index.htm. Accessed 3/1/2006. 

97See also Paine, M., Macbeth, A., and 

Henderson, M. (2003). The Danger to Young 

Pedestrians from Reversing Motor Vehicles. 18th 

International Technical Conference on the 

Enhanced Safety of Vehicles. Paper Number 466. 

98CDC, Clinical Growth Charts. Birth to 36 

months: Boys; Length-for-age and Weight-for-age 

percentiles. Published May 30, 2000 (modified 

4/20/2001) CDC, Clinical Growth Charts. Birth to 36 

months: Girls; Length-for-age and Weight-for-age 

percentiles. Published May 30, 2000 (modified 

4/20/2001). 

TABLE 10—CORRELATION BETWEEN HUMAN-BASED REAR BLIND ZONE AREA MEASURED OVER VARIOUS FIELD SIZES

AND BACKING CRASHES (SORTED BY CORRELATION COEFFICIENT) 

Measurement field dimensions 

(width by length) 

Correlation 

coefficient 

Probability 

occurred by 

chance 

50W x 10L ............................................................................................................................................................... 0.60117 0.0039 

40W x 10L ............................................................................................................................................................... 0.60117 0.0039 

30W x 10L ............................................................................................................................................................... 0.58233 0.0056 

30W x 50L ............................................................................................................................................................... 0.55212 0.0095 

40W x 40L ............................................................................................................................................................... 0.54681 0.0103 

30W x 40L ............................................................................................................................................................... 0.53635 0.0122 

20W x 40L ............................................................................................................................................................... 0.52621 0.0143 

50W x 50L* .............................................................................................................................................................. 0.52375 0.0148 

20W x 50L ............................................................................................................................................................... 0.52367 0.0148 

* Blind zone area measured over a field this size was found by preliminary analysis of laser-based measurement data to be well correlated with 

backing crashes. 

Considering the assessment of 

backover crash risk by pedestrian 

location described in Section IV.E of 

this notice, the results presented in 

Figure 1 suggest that a measurement 

field centered behind the vehicle and 

approximately 12 feet wide by 36 feet 

long would address pedestrian locations 

having relative crash risks of 0.15 and 

higher. Given that the analysis 

described in Appendix A suggests that 

backover crash risk extends a fair 

distance (38 ft or more) out from the 

vehicle, it may result in a more valid 

characterization of rear visibility if a 

range similar to this were used for a rear 

visibility measurement field. 

For NHTSA’s 2008 rear visibility 

measurement effort, a measurement 

field of 50 feet long by 50 feet wide test 

area was used to ensure that sufficient 

data were available for use in 

subsequent correlation analyses relating 

measurement field and backing crashes. 

However, based on a combination of the 

results of the three analyses summarized 

above, a field size centered behind the 

vehicle and having the dimensions of 40 

feet square or 50 feet is used on the 

analyses discussed in this section. 

2. Coarseness of the Rear Visibility 

Measurement Field’s Test Grid 

A measurement field covered by a test 

grid consisting of 1-foot squares was 

used. This level of grid detail has 

provided meaningful rear visibility data 

in past NHTSA testing, and has been 

used to produce rear blind zone area 

data that have been successfully 

correlated with backing crash risk. 

3. Use of an H-Point Machine for Rear 

Visibility Measurement 

To facilitate a repeatable test 

procedure, an H-Point machine,95 used 

by the agency for many other standards 

and representing a 50th percentile adult 

male was used in place of a human 

driver for this measurement effort. The 

50th percentile adult male approximates 

the midpoint for driver height, and has 

been used by other organizations 96, 97

conducting similar visibility 

measurement research. An H-Point 

machine was selected to provide a 

standardized representation of the 

seated posture of an adult male driver. 

The H-point machine’s standard 

configuration was modified to 

incorporate a fixture mounted in place 

of the device’s neck to hold the laser 

pointing devices in specific positions to 

correspond to selected eye points for a 

50th percentile adult male driver (as 

described below). 

4. Rear Visibility Measurement Test 

Object Height 

NHTSA’s rear visibility tests to date 

have been based on a test object height 

representing the approximate height of 

a 1-year-old child. As indicated earlier 

in this notice, 1-year-old children are 

the most frequent (approximately 26 

percent of all backovers) victims of fatal 

backover incidents. The height chosen 

to represent a 1-year-old child in 

NHTSA’s tests to date was determined 

by averaging standing height values 

from the Center for Disease Control’s 

(CDC) growth chart 98 (see Table 11 

below) for a male and female 1-year-old 

child. The average height value obtained 

was 29.4 inches. 

TABLE 11—50TH PERCENTILE CHILD HEIGHT

Age 1 2 3 4 5 6 7 8 9 10 

Height—Girl ........................................ 29 .125 33 .5 37.2 39 .5 42 .5 45 .25 47 .75 50 .25 52.2 54.5 

Height—Boy ....................................... 29 .6 34 37.5 40 .25 43 45 .5 48 50 .5 52.5 54.5 

Source: CDC, 2000. 

5. Laser Detector (in Lieu of a Visual 

Target) 

To improve the efficiency of our test 

procedure, NHTSA’s rear visibility 

measurement effort in 2008 used a 

different test object than used in prior 

measurements. This new test object 

incorporates a laser beam detector that 

automatically produces an audible 

signal when the laser beam, simulating 

the driver’s line of sight, intersects with 

the laser detector. Since laser beams can 

Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9509 

99SAE J826, Devices for Use in Defining and 

Measuring Vehicle Seating Accommodation, Rev. 

JUL95. 100 49 CFR 571.208, Standard No. 208; Occupant 

crash protection. 101 49 CFR 571.212, Standard No. 212; 

Windshield mounting. 102 49 CFR 571.219, Standard No. 219; 

Windshield zone intrusion. 103 49 CFR 571.301, Standard No. 301; Fuel 

system integrity. 

104This 32.5 inch measurement is based on 

sitting height of 36.3 inches for 50th percentile 

adult males aged 20 and over. See CDC Web site 

at: http://www.cdc.gov/nchs/about/major/nhanes/ 

anthropometric_measures.htm. 

be difficult to detect with the human 

eye, even in low light conditions, use of 

a laser beam detector would improve 

both the accuracy and speed of test 

conduct. 

The laser detector target was 

constructed with a commercial laser 

detector mounted vertically on a post. 

The base of the post was a 12-inch 

square of wood used to stabilize the 

fixture and center it within a 1-foot grid 

square. The target’s detection field was 

horizontally centered with respect to the 

post and base. The bottom of the laser 

detector’s approximately 2-inch tall 

detection field was aligned at a vertical 

height of 28 inches, to simulate a 30- 

inch overall detection height. 

For this approach to be usable and 

accommodate the 50 feet long test grid 

and all possible lengths of vehicles to be 

measured, the particular laser pointing 

device and laser beam detector were 

required to have performance ranges of 

at least 70 feet. 

An alternative approach, without a 

laser detector device, would be to rely 

on a test operator to visually confirm 

that the laser beam contacted the test 

object within the detection area while 

the test object was positioned within a 

particular location on the test grid. 

6. Eye Midpoint Locations for Use in 

Positioning Laser Pointing Devices 

NHTSA researchers experimentally 

determined the most appropriate 

locations for the lasers used to represent 

the line of sight for a driver glancing 

over the right and left shoulder. Human 

eye locations for three male drivers of 

50th percentile height were determined 

using photometric measurements while 

these drivers glanced at a cone 

positioned 25 feet behind a vehicle and 

approximately at its centerline and 

while looking directly (i.e., 90 degrees 

from forward) out the left and right 

sides of the vehicle. Photographs were 

taken from the rear and right (passenger) 

side of the vehicle for each of the three 

drivers and three vehicles. Driver eye 

positions for each vehicle were 

determined for both rear-looking 

glancing postures (rearward over the left 

and right shoulders) and both sidelooking glancing postures (left and 

right). These eye positions were 

determined with respect to the vehicles’ 

seats using a scale of rigid rulers. 

Researchers calculated an average left 

and right eye point locations to 

determine a midpoint between the left 

and right eye for each of the four 

postures. These midpoint values, which 

were used to identify locations of the 

laser pointing device to simulate a 

driver’s line of sight, are provided in 

Table 12 below. NHTSA welcomes 

comments on the validity and 

appropriateness of these eye points for 

use in evaluating a vehicle’s rear 

visibility for a 50th percentile male 

driver. 

TABLE 12—LEFT-RIGHT EYE MIDPOINT LOCATIONS FOR POSTURE OF DRIVER GLANCING REARWARD AND TO EITHER SIDE

Glancing rearward over the: 

Longitudinal (distance 

forward of the head restraint’s vertical face) 

(in.) (x) 

Lateral offset from the 

vertical centerline of the 

seat (in.) (y) 

Vertical with respect to 

H-Point (in.) (z) 

Left shoulder ................................................................................ 3.5 5.5 26.5 *

Right shoulder .............................................................................. 5.3 7.0 26.5 *

Left window (¥90 degrees from forward) ................................... 7.6 ¥5.5 26.5 *

Right window (90 degrees from forward) .................................... 7.6 5.0 26.5 *

* Note: These measurements assume that the distance from the seat pan to the H-Point is 3.6 inches. 

7. Vehicle Setup 

Vehicle setup conditions may be an 

important part of a repeatable visibility 

measurement procedure. Considerations 

which we used for our recent, laserbased measurements are detailed below. 

Fuel Tank—Ensure that the vehicle’s 

fuel tank is filled to capacity, to provide 

a consistent fuel level (can affect vehicle 

pitch). 

Vehicle Tires—The vehicle’s tires 

should be set to their recommended 

inflation pressures (can affect vehicle 

pitch). 

Vehicle Position on Test Grid— 

Position the vehicle on a flat, level test 

grid such that it is properly aligned (i.e., 

rear bumper flush with the ‘0’ foot line, 

vehicle centered on the ‘0’ longitudinal 

axis of the test grid). 

Vehicle Windows—The vehicle’s 

windows should be closed, clean, and 

clear of obstructions (e.g., window 

stickers). 

H-Point Device Configuration—Place 

the H-Point device in the driver’s seat 

and adjust the seat as follows: 

• Install the H-Point machine in the 

vehicle per the installation procedure 

outlined in SAE J826.99

• Adjust the driver’s seat to the 

longitudinal adjustment position 

recommended by the manufacturer for a 

50th percentile adult male as specified 

in FMVSS Nos. 208,100 212,101 219 

(partial),102 and 301 103 compliance 

testing. If this recommended adjustment 

setting is not available, position the seat 

at the midpoint of the longitudinal 

adjustment range. If no midpoint is 

selectable, then position the seat at the 

first notch rearward of the midpoint. 

• Adjust the driver’s seat to the 

vertical adjustment position 

recommended by the manufacturer for a 

50th percentile adult male as specified 

in FMVSS Nos. 208, 212, 219 (partial), 

and 301 compliance testing. If this 

recommended adjustment setting is not 

available, position the seat at the lowest 

point of all vertical adjustment ranges 

present. 

• Use the H-Point machine to adjust 

the driver’s seat back angle at the 

vertical portion of the H-Point 

machine’s torso weight hanger to that 

recommended by the manufacturer for a 

50th percentile adult male as specified 

in FMVSS 208, 212, 219 (partial), and 

301 compliance testing. If this 

recommended adjustment setting is not 

available, adjust the seat back angle to 

25 degrees, as specified in SAE J826. 

• Adjust the driver’s seat head 

restraint such that the distance from the 

H-Point to the topmost point of the head 

restraint, as measured along a line 

parallel to the seat back, is 32.5 

inches.104 If a distance of 32.5 inches is 

not attainable given the adjustment 

range of the head restraint or detent 

9510 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

positions, the closest detent position to 

that height should be used. 

• For any head restraints with 

longitudinal adjustment, the restraint 

should be positioned fully forward. 

Vehicle Seat Positioning—Adjust all 

seats in positions other than the driver’s 

as follows: 

• Vehicles with standard stowable 

second or third row seats should have 

all seats in an upright, occupant-ready 

position. This configuration provides a 

consistent approach for rear seat 

positioning to avoid vehicle-to-vehicle 

test differences. If a vehicle is offered 

with an optional original equipment 

third row seat, the vehicle should be 

measured in this seating configuration 

to assess the vehicle’s rear visibility 

characteristics in this worst-case 

condition. 

• For seats with longitudinally 

adjustable head restraints, the restraint 

should be positioned at the midpoint of 

longitudinal adjustment 

• For seats with vertically adjustable 

head restraints, the restraint should be 

positioned in the lowest possible 

position. This configuration provides a 

consistent approach for head restraint 

positioning to avoid vehicle-to-vehicle 

test differences. 

• For seats with an adjustable seat 

back angle, adjust the seat back angle to 

that recommended by the manufacturer 

for a driver’s seat back angle position for 

a 50th percentile adult male as specified 

in FMVSS 208, 212, 219 (partial), and 

301 compliance testing. If this 

recommended driver’s seat back angle 

setting is not available, adjust the seat 

back angle to 25 degrees. 

• Any rear seating position shoulder 

belts originating from the headliner 

(e.g., for use in rear center seating 

positions) should be latched into their 

receivers at the seat bite. 

8. Measurement Procedure 

Once the vehicle has been properly 

set and the laser fixture has been set up, 

the laser devices are turned on and a 

pre-test is performed. To ensure that the 

laser device and laser detector are 

capable of performing the test, the laser 

device shall be properly mounted at the 

required driver eye point position (as 

indicated in Table 12), and aimed at the 

laser detector test object which shall be 

centered at a distance of 50 feet aft of 

the vehicle’s bumper to determine 

whether the laser detector is able to 

sense the laser beam. This confirmation 

pre-test shall also be performed for the 

laser detector test object positioned at a 

distance of 50 feet from the rear bumper 

and 25 feet laterally to either side of the 

vehicle. If the laser detector detects the 

laser beam (e.g., as indicated by a 

‘‘beep’’ or other confirming signal) in 

each of these three locations, then the 

equipment is considered to perform at 

an acceptable level for use in this test 

procedure. 

To complete the rear visibility 

measurements, the laser devices while 

maintaining the x, y, z coordinates may 

be manually or automatically 

maneuvered to pan the area behind the 

vehicle in both the vertical and 

horizontal directions. The vertical 

extent of the laser beam movement shall 

extend from the lower edge of the rear 

window to the horizon. The horizontal 

range of laser motion shall permit the 

evaluation of the direct visibility of the 

test object as positioned within 1 foot of 

the rear bumper and 25 feet to both 

sides of the vehicle’s centerline. 

The test object is placed on the grid 

one time in each 1-foot square behind 

the vehicle. The test observer listens to 

determine whether the laser detector 

beeps (or otherwise signals) to indicate 

that the detector field has been 

contacted by a laser beam. The test 

object is considered visible if the laser 

detector beeps when a laser beam 

intersects with the test object. An 

operator records this measurement and 

repeats the prior steps for all positions 

in the grid. 

Observations About Available Rear 

Visibility Measurement Procedures 

The above descriptions summarize 

NHTSA’s knowledge of existing 

procedures for measuring vehicles’ rear 

visibility. NHTSA seeks comments on 

the utility of these methods as objective 

rear visibility assessment methods. 

While the noted laser-based 

measurement method appears to 

provide a robust, objective test method, 

the repeatability of the method must be 

confirmed. Therefore, to further assess 

the utility of our laser-based rear 

visibility measurement procedure, we 

also assessed the repeatability of the test 

method as described in the following 

section. 

B. Rear Visibility Measurement Method 

Variability 

To assess the variability of NHTSA’s 

improved rear visibility test method 

using laser pointing devices, four test 

vehicles were measured using the laserbased rear visibility measurement 

protocol. The measurement procedure 

was completed four times for each 

vehicle, including repositioning of the 

vehicle on the test grid. Results of these 

measurements are illustrated in Figure 

13. As indicated in Table 13, the rear 

blind zone area data varied less than 3.2 

percent of the measured value. This 

variability is believed to be due to the 

test vehicle’s alignment of the rear 

bumper with respect to the lateral grid 

axis. More carefully aligning the vehicle 

on the test grid to ensure that the 

vehicle’s centerline is aligned with the 

test grid’s longitudinal axis will likely 

reduce variation to 2 percent or less. 

Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9511 

105Presentation to NHTSA, January 28, 2009 

meeting; Alliance for Automotive Manufacturers. 

Available at Docket Number 2009–0041. 

TABLE 13—REAR BLIND ZONE AREA MEASUREMENT REPEATABILITY RESULTS AND ANALYSIS

Vehicle Test 1 Test 2 Test 3 Test 4 Avg Std. 

dev. Min Max Range (max-min) 

Std dev/ 

avg 

(percent) 

2005 Chrysler 300C ............................. 1608 1631 1590 1604 1608 17.0 1590 1631 41 1.1 

2006 BMW 330i ................................... 1523 1542 1533 1513 1528 12.5 1513 1542 29 0.8 

2007 Cadillac Escalade ....................... 1863 1800 1889 1887 1860 41.5 1800 1889 89 2.2 

2007 Honda Odyssey .......................... 1783 1834 1705 1739 1765 55.9 1705 1834 129 3.2 

In summary, this rear visibility 

measurement procedure seems to 

provide for a controlled vehicle setup 

(for test consistency and repeatability) 

by its use of an automated test object, 

and dynamic laser movement. 

C. Comparison of Human-Based Versus 

Laser-Based Rear Visibility 

Measurement Protocols 

NHTSA compared rear visibility data 

for 18 vehicles that were measured 

using both the human-based and laserbased rear visibility measurement 

procedures to assess the results (i.e., 

similar vehicle rankings, etc.) of the test 

procedure under consideration. This 

comparison found data from the two 

measurement methods to be different 

but correlated to a statistically 

significant degree. 

D. Input From Industry Regarding Rear 

Visibility Measurement 

NHTSA received input from the 

Alliance for Automotive Manufacturers 

regarding the method for assessment for 

the purposes of assessing the need for a 

rear visibility enhancement 

countermeasure. The Alliance suggested 

a protocol similar to that used in 

FMVSS No. 111 for the measurement of 

the field of view of the interior rear 

mirror.105 This protocol would use a 

95th percentile male driver. No 

additional details regarding a rear 

visibility measurement procedure were 

provided by the Alliance or any other 

group. 

E. Questions 

(1) While a 50th percentile male body 

size was used for the rear visibility 

measurements outlined here, we note 

that FMVSS No. 111 currently requires 

that the driver’s eye reference point be 

at a nominal location appropriate for 

any 95th percentile male driver for the 

assessment of rearview mirror field of 

view compliance. We further note that 

under FMVSS No. 111 the driver’s eye 

location for school bus mirror 

compliance testing is the eye location of 

a 25th percentile female driver. NHTSA 

requests comment on the use of the 50th 

percentile male driver size as a 

midpoint in terms of driver height and 

whether using multiple driver heights 

for these tests would cause undue 

hardship relative to the safety value of 

assessing different driver heights. 

Specific information regarding 


EP04MR09.012</GPH>
9512 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

106Henry Dreyfuss Associates (2002). The 

Measure of Man and Woman; Human Factors in 

Design (rev.). New York: John Wiley & Sons. 

107 ISO 17386:2004 Transport information and 

control systems—Manoeuvring Aids for Low Speed 

Operation (MALSO)—Performance requirements 

and test procedures. 

108Presentation to NHTSA, January 28, 2009 

meeting; Alliance for Automotive Manufacturers. 

Available at Docket Number 2009–0041. 

109See Appendix B, Method for Assessment of 

Backover Crash Risk by Pedestrian Location. 

additional cost, if any, that would be 

incurred by vehicle manufacturers due 

to the use of different driver sizes for 

these different portions of FMVSS No. 

111 is requested. 

(2) NHTSA has been using seating 

position settings recommended by the 

vehicle manufacturers for agency crash 

tests. For most vehicles, the vertical seat 

position setting recommended for seats 

with vertical adjustability is the lowest 

position. NHTSA seeks comment on 

whether this setting is the most suitable 

position for a 50th percentile male, or if 

a midpoint setting would be more 

appropriate for measuring rear visibility. 

NHTSA also seeks comment on whether 

the specific crash test seating 

specifications used are the most 

appropriate for this context. 

(3) NHTSA seeks comment on the 

placements of head restraints. For 

example, would our test procedure 

result in the elimination of rear head 

restraints or a reduction in their size? If 

so, please identify the affected vehicles 

and explain why the rear head restraints 

particularly impair visibility in those 

vehicles. Similarly, NHTSA seeks 

comment on the approach to setting the 

longitudinal position of all adjustable 

head restraints for rear visibility 

measurements. While longitudinally 

adjustable head restraints positioned 

fully forward may minimize the chance 

of whiplash, a more reasonable option 

for this test may be to position the head 

restraint at the midpoint of the 

longitudinal adjustment range. 

(4) In our testing, we found that the 

laser beam is difficult to detect visually. 

Therefore, we used the laser detector. 

NHTSA invites comment on the 

availability of other options for 

detecting the laser beam as used in this 

test that does not involve the use of an 

electronic laser detector. 

(5) For locating the laser devices at 

the selected driver eye points, is there 

another device besides the H-point 

device which can be utilized for this 

purpose or should the agency? For 

simplicity, should eye points be 

indicated in a similar fashion as is 

currently in FMVSS No. 111 for school 

bus testing in which a single eye point 

is located at a specified distance from 

the seat cushion/seat back intersection 

and within a 6-inch semi-circular area? 

XI. Options for Assessing the 

Performance of Rear Visibility 

Countermeasures 

To assess the minimum performance 

of a required rear visibility 

enhancement countermeasure, a 

compliance test would need to be 

developed. This test would serve to 

assess whether the system permits 

obstacles and standing children in the 

path of a backing vehicle to be detected 

over a minimum required area. 

Considerations that the agency has 

identified which may be necessary for 

this new compliance test are described 

below. 

A. Countermeasure Performance Test 

Object 

A test object may be needed to assess 

whether the countermeasure functions 

over a specified area. Based on the crash 

data and our testing to date, we have 

used a test object with an approximate 

height of 30 inches (0.762 meters). As 

indicated earlier, this height 

corresponds to the average height of a 1- 

year-old child. To further simulate the 

appearance of a 1-year-old child, some 

have suggested other dimensional 

characteristics. Based on our research 

we have found that that the object 

would need to be cylindrical in shape 

with a diameter of 5 inches, to represent 

the breadth of the average 1-year-old 

child’s head.106

Depending on the type of 

countermeasure, the composition of the 

test object may be important. For 

example, rearview video systems would 

display images of objects of all possible 

material types, but ultrasonic and radar 

sensors are better at detecting some 

materials than others. NHTSA is aware 

of the requirement detailed in ISO 

17386 107 for use of a cylinder composed 

of polyvinyl chloride (PVC) pipe to test 

the detection performance of ultrasonic 

parking aids. NHTSA welcomes input 

regarding all aspects of the test object. 

The Alliance for Automotive 

Manufacturers has indicated to NHTSA 

that their suggestion is to use a 

cylindrical test object with a height of 

1 meter (39.37 inches) and a diameter of 

0.3 meters (11.3 inches).108 No 

requirements for material composition 

of the test object were suggested by the 

Alliance. 

B. Countermeasure Performance Test 

Area 

One possible compliance test area can 

be identified using the results of the 

Monte Carlo simulation (illustrated in 

Figure 1 and described in Appendix A) 

that examined backover crash risk as a 

function of a pedestrian’s location 

behind a vehicle.109 NHTSA used these 

results to define an area behind a 

vehicle that must be visible to the 

driver. Based on these results, an area 

over which the test object should be 

visible could be defined to include an 

area 8 feet wide at the vehicle’s rear 

bumper that widens symmetrically 

along diagonal lines of 45 degrees with 

respect to the vertical plane of the 

vehicle’s rear bumper and extending 

outward from the vehicle’s rear corners. 

The maximum longitudinal range of this 

required visible area is 40 feet, as shown 

in Figure 14. 

BILLING CODE 4910–59–P 

Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9513 

BILLING CODE 4910–59–C 


EP04MR09.013</GPH>
9514 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

110Presentation to NHTSA, January 28, 2009 

meeting; Alliance for Automotive Manufacturers. 

Available at Docket Number 2009–0041. 

111 49 CFR 571.111, Standard No. 111, Rearview 

Mirrors. 

Alternatively, the test area could be 

defined based on the results of the 

above mentioned Monte Carlo analysis, 

as well as the assessments of the 

correlation between vehicles’ rear blind 

zone areas and backing crash data. The 

test area suggested by the combination 

of results of these three analyses is one 

that is centered behind the vehicle and 

having the dimensions of 40 feet square 

or 50 feet square. 

The Alliance for Automotive 

Manufacturers has indicated to NHTSA 

that their suggestion is to use a test area 

composed of 9 test object locations 

behind the vehicle.110 The 9 test object 

locations would consist of 3 rows of 3 

locations. The 3 rows would be 

positioned with one at the rear bumper, 

and two others positioned 1.5 meters 

and 3.0 meters aft of the rear bumper. 

The 3 lateral locations would consist of 

one at each lateral edge of the vehicle 

and the third at the vehicle’s 

longitudinal centerline. By this scheme, 

the test area size would be based on 

each vehicle model’s individual width, 

and therefore may be different for all 

vehicle models. 

C. Countermeasure Performance Test 

Procedure 

The test procedure currently used for 

school bus mirrors (section 13, ‘‘School 

bus mirror test procedures’’ of FMVSS 

No. 111, ‘‘Rearview mirrors’’) 111 could 

be modified and used to determine 

countermeasure performance. For 

example, a still photography camera 

placed with the imaging sensor located 

at a midpoint eye location for a 50th 

percentile male (rather than a 95th 

percentile male), could be used to 

photograph the test objects as they are 

displayed in the countermeasure 

system’s visual display. As is done now 

with cones in rear visibility 

measurements, for all specified 

locations of the test object on the test 

grid, at least a 3-inch tall by 3-inch wide 

portion of the test object would be 

required to be visible in order for the 

rear visibility enhancement system to be 

deemed compliant. This minimum 

detection area would represent the area 

that would need to be visible to 

adequately identify the test object. 

D. Questions 

(1) NHTSA invites comments on the 

need for and adequacy of the described 

area which rear visibility 

countermeasure systems may be 

required to detect obstacles. NHTSA is 

particularly interested in any available 

data that may suggest an alternative area 

behind the vehicle over which a rear 

visibility enhancement countermeasure 

should be effective? Is the described 

area of coverage unrealistically large? Is 

it adequate to mimic real world angles 

at which children may approach 

vehicles? 

(2) Is it reasonable to define the limits 

of the test zone such that it begins 

immediately behind the rear bumper for 

the test object defined here or should a 

gap be permitted before the visibility 

zone begins? What additional factors 

should the agency consider in defining 

the zone? 

(3) NHTSA requests comments on 

potentially requiring only the perimeter 

of the specified area to be tested for rear 

visibility enhancement systems. For 

video-based rear visibility 

countermeasure systems, NHTSA 

assumes that confirming the visibility of 

the test object over the perimeter of the 

required area is sufficient, since a 

system able to display the object at the 

perimeter of the required area should 

also be able to display the object at all 

points in between the extremities. Is this 

a reasonable assumption? 

(4) Would vehicles with rearview 

video cameras mounted away from the 

vehicle centerline have the ability to 

detect the test object over the area under 

consideration? Is there flexibility to 

relocate such off-center cameras to meet 

the requirements under consideration, if 

necessary? 

(5) NHTSA seeks comment as to the 

availability of any mirrors that may have 

a field of view that encompasses a range 

of 50 feet, as well as the quality of image 

that might be provided over such a 

range. How different is the image size 

and resolution, and how significant are 

the differences to the mirrors’ potential 

effectiveness? 

(6) If a gap is permitted behind the 

vehicle before the visibility zone begins, 

how will systems prevent children who 

may be immediately behind a vehicle 

from being backed over? 

(7) NHTSA seeks input on what level 

of ambient lighting would be 

appropriate to specify for conduct of 

this compliance test. What other 

environmental and ambient conditions, 

if any, should the agency include in the 

test procedure? 

(8) NHTSA invites input regarding the 

composition of the countermeasure 

compliance test object and the types of 

technologies that are likely to be able to 

provide coverage of the related test area. 

XII. Options for Characterizing Rear 

Visibility Countermeasures 

Existing rear visibility technologies, 

which formed the basis for NHTSA’s 

effectiveness estimates, already contain 

certain performance levels specified by 

vehicle manufacturers. Some of these 

specifications may be necessary to 

ensure that our effectiveness estimates 

will be applicable to real-world crashes 

and to prevent for inferior systems from 

entering the fleet. However, NHTSA is 

not aware of consensus industry 

specifications (e.g., SAE standards) or 

published recommended practices for 

rear visibility enhancement systems 

other than mirrors that may serve this 

purpose. While FMVSS No. 111 

contains performance specifications for 

convex mirrors, the mirror 

specifications contained therein may 

not be adequate for this application. As 

such, certain performance specifications 

may be necessary in order to ensure 

adequate system effectiveness. NHTSA 

solicits comment on whether the 

performance aspects we have identified 

are appropriate or whether additional 

specifications, particularly for electronic 

image-based visual displays, should be 

considered. NHTSA has not evaluated 

these performance specifications nor 

have we developed possible compliance 

tests for them. 

A. Options for Display Characteristics 

Given that a particular rear visibility 

countermeasure technology has not 

been specified, the type of visual 

display associated with a rear visibility 

countermeasure has the potential to take 

a variety of forms. Such visual displays 

may include mirrors, flashing lights 

from sensor-based rear object detection 

system, or a video-based image display. 

Some characteristics relevant to possible 

visual display types are described 

below. 

Performance Criteria Which May be 

Needed for All Rear Visibility 

Enhancement Countermeasure Displays 

(e.g., Rearview Video System Displays, 

Mirrors, and Electronic Warning 

Displays) 

Overall display size—The minimum 

overall image size should be defined to 

ensure that drivers will be able to detect 

small children in the visual display. If 

the image size is too small, the 

effectiveness of the system may be 

impacted by a driver’s inability to 

identify a child or other object. 

Image resolution—It may be necessary 

to define the minimum image resolution 

so that drivers will be able to identify 

objects in the display. 

Image distortion—A maximum 

allowable distortion parameter may be 

Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9515 

112 General Motors, SAE Government and 

Industry Meeting, May 2008, oral presentation. 

113Measured in cd/m2. 

114Mazzae, E.N., Barickman, F.S., Baldwin, 

G.H.S., and Ranney, T.A. (2008). On-Road Study of 

Drivers’ Use of Rearview Video Systems 

(ORSDURVS). National Highway Traffic Safety 

Administration, DOT 811 024. 

necessary to ensure that image quality is 

sufficient to allow drivers to accurately 

identify objects located behind the 

vehicle. 

Image minification—To ensure that 

objects behind the vehicle appear in the 

image of the area behind the vehicle as 

presented by the countermeasure’s 

display with sufficient size to allow 

them to be identified by drivers, a 

maximum allowable minification level 

may be necessary. 

Environmental performance—It may 

be necessary to specify minimum 

environmental requirements under 

which systems would be expected to 

operate in common real world 

conditions. 

Additional Performance Criteria Which 

May be Needed for Electronic Visual 

Displays (e.g., Rearview Video Systems, 

Electronic Warning Displays) 

Display location—In order to facilitate 

a driver’s effective use of an electronic 

visual display, it may be beneficial to 

specify a permitted location for the 

display unit and image. For example, a 

rearview video image present in the 

interior rearview mirror must be 

displayed on the left side of the mirror 

so that the distance between the driver 

and image is not too large. 

Overall display size—For electronic, 

rearview video system displays, NHTSA 

is considering specifying a minimum 

image size of 3.25 inches measured 

diagonally for an electronic visual 

display with aspect ratio of 4:3 112 (or 

approximately 4-inch diagonal size for 

16:9 aspect ratio displays). 

Brightness—A minimum brightness 

value 113 may be necessary to ensure 

that the display image can be seen by 

drivers in a wide variety of ambient 

conditions, such as glare from sunlight 

or ambient light. 

Contrast ratio—Minimum contrast 

ratio may be necessary to ensure that the 

display image can be seen by drivers in 

a wide variety of ambient conditions. 

Image response time—A minimum 

response time for the system to display 

an image of the area behind the vehicle 

may be necessary to enable a driver to 

engage the system while backing. 

NHTSA is considering a maximum of 

1.25 seconds based on our research to 

date.114

Image ‘‘linger’’ time—To limit 

unintended distraction to drivers, the 

maximum image linger time (i.e., the 

time that the visual display remains on 

after the vehicle’s transmission has been 

shifted out of reverse gear), may be 

specified. Some linger time is desirable 

for situations where frequent transitions 

from reverse to forward gear are needed 

to adjust a vehicle’s position (e.g., 

parallel parking and hitching). NHTSA 

is considering a minimum of 4 seconds 

but not more than 8 seconds of linger 

time is appropriate after the vehicle is 

shifted from the reverse position. 

Options for Other Display 

Characteristics 

NHTSA does not believe that a 

malfunction telltale is necessary for 

rearview video systems, since video 

camera or visual display failure would 

be indicated by the apparent lack of 

image presented in the visual display. 

We invite comments on this point and 

any evidence that would suggest that 

such an indicator may be necessary. 

B. Options for Rearview Video System 

Camera Characteristics 

Currently, NHTSA does not have data 

which could be used to establish 

minimum specifications for a rearview 

video system’s camera. However, based 

upon our knowledge of the current 

technology the agency believes that 

requirements for the following 

categories might be necessary: Low light 

performance requirements; resolution; 

and environmental performance limits/ 

ranges. 

C. Questions 

(1) Are there any existing industry 

consensus standards for rear visibility 

enhancement systems which address 

the parameters outlined in this section? 

Are there any ongoing efforts to develop 

such industry consensus standards? If 

so, when will the standards be 

published? 

(2) Are there additional parameters 

which should be specified to define a 

rear visibility enhancement system? 

What should the minimum specified 

performance be for each parameter? 

(3) Are future rear visibility systems 

anticipated which may have 

significantly different visual display 

types that may require other display 

specification parameters? 

XIII. Conclusion 

In developing this notice, NHTSA 

tried to address the concerns of all 

stakeholders. Your comments will help 

us develop a rearward visibility 

standard to be included as part of 

FMVSS No. 111. We invite you to 

provide different views on the questions 

we ask, new approaches and 

technologies about which we did not 

ask, new data, insight as to how this 

notice may affect you, or other relevant 

information. We welcome your views on 

all aspects of this notice but we 

especially request comments on the 

specific questions articulated 

throughout this document. 

XIV. Public Participation 

How do I prepare and submit 

comments? 

Your comments must be written and 

in English. To ensure that your 

comments are correctly filed in the 

Docket, please include the docket 

number of this document in your 

comments. 

Your comments must not be more 

than 15 pages long. (49 CFR 553.21). We 

established this limit to encourage you 

to write your primary comments in a 

concise fashion. However, you may 

attach necessary additional documents 

to your comments. There is no limit on 

the length of the attachments. 

Please submit two copies of your 

comments, including the attachments, 

to Docket Management at the address 

given above under ADDRESSES. 

Comments may also be submitted to 

the docket electronically by logging onto 

the Docket Management System Web 

site at http://www.regulations.gov. 

Follow the online instructions for 

submitting comments. 

Please note that pursuant to the Data 

Quality Act, in order for substantive 

data to be relied upon and used by the 

agency, it must meet the information 

quality standards set forth in the OMB 

and DOT Data Quality Act guidelines. 

Accordingly, we encourage you to 

consult the guidelines in preparing your 

comments. OMB’s guidelines may be 

accessed at http://www.whitehouse.gov/ 

omb/fedreg/reproducible.html. DOT’s 

guidelines may be accessed at http:// 

dms.dot.gov. 

How can I be sure that my comments 

were received? 

If you wish Docket Management to 

notify you upon its receipt of your 

comments, enclose a self-addressed, 

stamped postcard in the envelope 

containing your comments. Upon 

receiving your comments, Docket 

Management will return the postcard by 

mail. 

How do I submit confidential business 

information? 

If you wish to submit any information 

under a claim of confidentiality, you 

should submit three copies of your 

complete submission, including the 

information you claim to be confidential 

9516 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

business information, to the Chief 

Counsel, NHTSA, at the address given 

above under FOR FURTHER INFORMATION

CONTACT. In addition, you should 

submit two copies, from which you 

have deleted the claimed confidential 

business information, to Docket 

Management at the address given above 

under ADDRESSES. When you send a 

comment containing information 

claimed to be confidential business 

information, you should include a cover 

letter setting forth the information 

specified in our confidential business 

information regulation. (49 CFR Part 

512.) 

Will the agency consider late 

comments? 

We will consider all comments that 

Docket Management receives before the 

close of business on the comment 

closing date indicated above under 

DATES. To the extent possible, we will 

also consider comments that Docket 

Management receives after that date. If 

Docket Management receives a comment 

too late for us to consider in developing 

a final rule (assuming that one is 

issued), we will consider that comment 

as an informal suggestion for future 

rulemaking action. 

How can I read the comments submitted 

by other people? 

You may read the comments received 

by Docket Management at the address 

given above under ADDRESSES. The 

hours of the Docket are indicated above 

in the same location. You may also see 

the comments on the Internet. To read 

the comments on the Internet, go to 

http://www.regulations.gov. Follow the 

online instructions for accessing the 

dockets. 

Please note that even after the 

comment closing date, we will continue 

to file relevant information in the 

Docket as it becomes available. Further, 

some people may submit late comments. 

Accordingly, we recommend that you 

periodically check the Docket for new 

material. 

XV. Rulemaking Analyses and Notices 

Executive Order 12866 and DOT 

Regulatory Policies and Procedures 

Executive Order 12866, ‘‘Regulatory 

Planning and Review’’ (58 FR 51735, 

October 4, 1993), provides for making 

determinations whether a regulatory 

action is ‘‘significant’’ and therefore 

subject to OMB review and to the 

requirements of the Executive Order. 

The Order defines a ‘‘significant 

regulatory action’’ as one that is likely 

to result in a rule that may: 

(1) Have an annual effect on the 

economy of $100 million or more or 

adversely affect in a material way the 

economy, a sector of the economy, 

productivity, competition, jobs, the 

environment, public health or safety, or 

State, local, or Tribal governments or 

communities; 

(2) Create a serious inconsistency or 

otherwise interfere with an action taken 

or planned by another agency; 

(3) Materially alter the budgetary 

impact of entitlements, grants, user fees, 

or loan programs or the rights and 

obligations of recipients thereof; or 

(4) Raise novel legal or policy issues 

arising out of legal mandates, the 

President’s priorities, or the principles 

set forth in the Executive Order. 

We have considered the potential 

impact of this ANPRM under Executive 

Order 12866 and the Department of 

Transportation’s regulatory policies and 

procedures. As discussed above, there 

are a number of considerations and 

technologies that can be applied to 

address the issue of backovers and the 

agency lacks the necessary information 

to develop a proposal at this time. Based 

on the information we have, we 

developed this notice and placed in the 

docket a Preliminary Regulatory Impact 

Analysis to facilitate public input. 

Therefore, we have not yet determined 

whether or not this rulemaking will be 

economically significant under 

Executive Order 12866. However, this 

rulemaking action has been determined 

to be ‘‘significant’’ under the 

Department of Transportation’s 

Regulatory Policies and Procedures (44 

FR 11034; February 26, 1979) and has 

been reviewed by the Office of 

Management and Budget. 

Regulatory Flexibility Act 

Pursuant to the Regulatory Flexibility 

Act, 5 U.S.C. 601 et seq., no analysis is 

required for an ANPRM. However, 

vehicle manufacturers and equipment 

manufacturers are encouraged to 

comment if they identify any aspects of 

the potential rulemaking that may apply 

to them. 

Executive Order 13132 (Federalism) 

NHTSA has examined today’s 

ANPRM pursuant to Executive Order 

13132 (64 FR 43255, August 10, 1999) 

and concluded that no additional 

consultation with States, local 

governments or their representatives is 

mandated beyond the rulemaking 

process at this time. The agency has 

concluded that the document at issue 

does not have federalism implications 

because it does not have ‘‘substantial 

direct effects on the States, on the 

relationship between the national 

government and the States, or on the 

distribution of power and 

responsibilities among the various 

levels of government.’’ 

NHTSA’s safety standards can have 

preemptive effect in at least two ways. 

First, the National Traffic and Motor 

Vehicle Safety Act contains an express 

preemption provision: ‘‘When a motor 

vehicle safety standard is in effect under 

this chapter, a State or a political 

subdivision of a State may prescribe or 

continue in effect a standard applicable 

to the same aspect of performance of a 

motor vehicle or motor vehicle 

equipment only if the standard is 

identical to the standard prescribed 

under this chapter.’’ 49 U.S.C. 

30103(b)(1). It is this statutory command 

that would unavoidably preempt State 

legislative and administrative law, not 

today’s rulemaking, so consultation 

would be unnecessary. 

We are aware that, depending on the 

nature of the proposal ultimately 

adopted, federalism implications could 

arise. Currently, there is no Federal 

requirement regarding visibility of the 

area directly behind a passenger vehicle. 

As a result, any State laws or regulations 

that seek to regulate this aspect of 

performance would not currently be 

preempted by Federal law. However, if 

NHTSA issues a standard on the same 

aspect of performance, those State laws 

and regulations would be preempted if 

they differed from the Federal 

requirements. Thus, the possibility of 

statutory preemption of State laws and 

regulations does exist. At this time, we 

do not know of any State laws or 

regulations that currently exist that are 

potentially at risk of being preempted, 

but in this document do request 

comment on any existing or planned 

laws or regulations that would fall into 

this category. 

Second, the Supreme Court has 

recognized the possibility of implied 

preemption: State requirements 

imposed on motor vehicle 

manufacturers, including sanctions 

imposed by State tort law, can stand as 

an obstacle to the accomplishment and 

execution of a NHTSA safety standard. 

When such a conflict is discerned, the 

Supremacy Clause of the Constitution 

makes the State requirements 

unenforceable. See Geier v. American 

Honda Motor Co., 529 U.S. 861 (2000). 

NHTSA has considered today’s ANPRM 

and does not currently foresee any 

potential State requirements that might 

conflict with it. Without any conflict, 

there could not be any implied 

preemption. 

Executive Order 12988 (Civil Justice 

Reform) 

With respect to the review of the 

promulgation of a new regulation, 

Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9517 

section 3(b) of Executive Order 12988, 

‘‘Civil Justice Reform’’ (61 FR 4729, 

February 7, 1996) requires that 

Executive agencies make every 

reasonable effort to ensure that the 

regulation: (1) Clearly specifies the 

preemptive effect; (2) clearly specifies 

the effect on existing Federal law or 

regulation; (3) provides a clear legal 

standard for affected conduct, while 

promoting simplification and burden 

reduction; (4) clearly specifies the 

retroactive effect, if any; (5) adequately 

defines key terms; and (7) addresses 

other important issues affecting clarity 

and general draftsmanship under any 

guidelines issued by the Attorney 

General. This document is consistent 

with that requirement. 

Pursuant to this Order, NHTSA notes 

as follows. The preemptive effect of this 

document is discussed above. NHTSA 

notes further that there is no 

requirement that individuals submit a 

petition for reconsideration or pursue 

other administrative proceeding before 

they may file suit in court. 

Protection of Children From 

Environmental Health and Safety Risks 

Executive Order 13045, ‘‘Protection of 

Children from Environmental Health 

and Safety Risks’’ (62 FR 19855, April 

23, 1997), applies to any rule that: (1) 

Is determined to be ‘‘economically 

significant’’ as defined under Executive 

Order 12866, and (2) concerns an 

environmental, health, or safety risk that 

the agency has reason to believe may 

have a disproportionate effect on 

children. If the regulatory action meets 

both criteria, the agency must evaluate 

the environmental health or safety 

effects of the planned rule on children, 

and explain why the planned regulation 

is preferable to other potentially 

effective and reasonably feasible 

alternatives considered by the agency. 

While this document does not make 

any changes with regard to the standard 

at issue, the rulemaking is intended, in 

large part, to address a safety concern 

that is particularly applicable to young 

children. In response to the executive 

order and in alignment with the 

agency’s policies, we have tailored our 

research efforts addressed in this 

document to be particularly sensitive to 

the needs of children. These steps have 

included, but are not limited to, 

analyzing accident cases that involve 

children and designing testing 

procedures and performance criteria 

with particular emphasis on the 

ultimate goal of detecting and 

preventing accidents involving the 

youngest children. 

Paperwork Reduction Act 

Under the Paperwork Reduction Act 

of 1995 (PRA), a person is not required 

to respond to a collection of information 

by a Federal agency unless the 

collection displays a valid OMB control 

number. There is not any information 

collection requirement associated with 

this ANPRM. 

National Technology Transfer and 

Advancement Act 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (NTTAA), Public Law 104– 

113, (15 U.S.C. 272) directs the agency 

to evaluate and use voluntary consensus 

standards in its regulatory activities 

unless doing so would be inconsistent 

with applicable law or is otherwise 

impractical. Voluntary consensus 

standards are technical standards (e.g., 

materials specifications, test methods, 

sampling procedures, and business 

practices) that are developed or adopted 

by voluntary consensus standards 

bodies, such as the Society of 

Automotive Engineers. The NTTAA 

directs us to provide Congress (through 

OMB) with explanations when we 

decide not to use available and 

applicable voluntary consensus 

standards. There are no voluntary 

consensus standards developed by 

voluntary consensus standards bodies 

pertaining to this ANPRM. 

Unfunded Mandates Reform Act 

The Unfunded Mandates Reform Act 

of 1995 requires agencies to prepare a 

written assessment of the costs, benefits 

and other effects of proposed or final 

rules that include a Federal mandate 

likely to result in the expenditure by 

State, local or tribal governments, in the 

aggregate, or by the private sector, of 

more than $100 million annually 

(adjusted for inflation with base year of 

1995). This ANPRM would not result in 

expenditures by State, local or tribal 

governments, in the aggregate, or by the 

private sector in excess of $100 million 

annually. However, given the cost 

estimates of some of the technologies at 

issue, most relevantly RV video systems, 

it is very possible that the total cost of 

a proposed rule could substantially 

exceed $100 million. Given that, the 

agency has prepared a preliminary 

assessment of some of the possible costs 

of the technologies investigated in this 

ANPRM. 

National Environmental Policy Act 

NHTSA has analyzed this rulemaking 

action for the purposes of the National 

Environmental Policy Act. The agency 

has determined that implementation of 

this action will not have any significant 

impact on the quality of the human 

environment. 

Executive Order 13211 

Executive Order 13211 (66 FR 28355, 

May 18, 2001) applies to any 

rulemaking that: (1) Is determined to be 

economically significant as defined 

under E.O. 12866, and is likely to have 

a significantly adverse effect on the 

supply of, distribution of, or use of 

energy; or (2) that is designated by the 

Administrator of the Office of 

Information and Regulatory Affairs as a 

significant energy action. This 

rulemaking is not subject to E.O. 13211. 

Plain Language 

Executive Order 12866 and the 

President’s memorandum of June 1, 

1998, require each agency to write all 

rules in plain language. Application of 

the principles of plain language 

includes consideration of the following 

questions: 

• Have we organized the material to 

suit the public’s needs? 

• Are the requirements in the rule 

clearly stated? 

• Does the rule contain technical 

language or jargon that isn’t clear? 

• Would a different format (grouping 

and order of sections, use of headings, 

paragraphing) make the rule easier to 

understand? 

• Would more (but shorter) sections 

be better? 

• Could we improve clarity by adding 

tables, lists, or diagrams? 

• What else could we do to make the 

rule easier to understand? 

If you have any responses to these 

questions, please include them in your 

comments on this ANPRM. 

Regulatory Identifier Number (RIN) 

The Department of Transportation 

assigns a regulation identifier number 

(RIN) to each regulatory action listed in 

the Unified Agenda of Federal 

Regulations. The Regulatory Information 

Service Center publishes the Unified 

Agenda in April and October of each 

year. You may use the RIN contained in 

the heading at the beginning of this 

document to find this action in the 

Unified Agenda. 

Privacy Act 

Anyone is able to search the 

electronic form of all comments 

received into any of our dockets by the 

name of the individual submitting the 

comment (or signing the comment, if 

submitted on behalf of an association, 

business, labor union, etc.). You may 

review DOT’s complete Privacy Act 

Statement in the Federal Register 

published on April 11, 2000 (Volume 

9518 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

115Mazzae, E.N., Barickman, F.S., Baldwin, 

G.H.S., and Ranney, T.A. (2008). On-Road Study of 

Drivers’ Use of Rearview Video Systems 

(ORSDURVS). National Highway Traffic Safety 

Administration, DOT 811 024. 

116 Id. 

117Mazzae, E.N., Barickman, F.S., Baldwin, 

G.H.S., and Ranney, T.A. (2008). On-Road Study of 

Drivers’ Use of Rearview Video Systems 

(ORSDURVS). National Highway Traffic Safety 

Administration, DOT 811 024. 

118Mazzae, E.N., Barickman, F.S., Baldwin, 

G.H.S., and Ranney, T.A. (2008). On-Road Study of 

Drivers’ Use of Rearview Video Systems 

(ORSDURVS). National Highway Traffic Safety 

Administration, DOT 811 024. 

65, Number 70; Pages 19477–78) or you 

may visit http://www.regulations.gov. 

Issued on: February 26, 2009. 

Stephen R. Kratzke, 

Associate Administrator for Rulemaking. 

Appendix A—Methodology for 

Assessing Backover Crash Risk by 

Pedestrian Location 

Monte Carlo simulation was used to 

calculate a probability-based risk weighting 

for each square in a grid of 30-cm squares 

behind the vehicle. The grid of 30-cm squares 

extended 27 m back from the rear edge of the 

rear bumper of the vehicle, 6 m forward of 

the rear bumper, and 10.5 m to the left and 

to the right of the longitudinal centerline of 

the vehicle, resulting in a total of 7,700 

30-cm grid squares. The probability-based 

risk weightings for each grid square were 

based on the number of pedestrian-vehicle 

backing crashes predicted by the simulation 

for trials for which the pedestrian was 

initially (i.e., at the time that the vehicle 

began to back up) in the center of one square 

of the grid of 30-cm squares. For each Monte 

Carlo simulation trial, the pedestrian was 

initially placed in the center of one square of 

the grid of 30-cm squares. A total of 

1,000,000 Monte Carlo simulation trials were 

run with the pedestrian initially in the center 

of each square. Since the Monte Carlo 

simulation used had left-right symmetry, 

mirroring was used to increase the effective 

number of simulation trials to 2,000,000 for 

each grid square. 

Important assumptions were made about 

the behavior of the driver and the pedestrian 

for this analysis. The vehicle and pedestrian 

were assuming to begin moving at the same 

time and were assumed to be completely 

unaware of each other. Therefore, the 

motions of the vehicle and pedestrian were 

totally independent of the each other. Note 

that it was possible for the pedestrian to walk 

or run into the vehicle. If the impact was 

with the rear of the vehicle, a back-over 

incident was considered to have resulted. If 

the impact was with the side or front of the 

vehicle, the crash was not counted as a 

backing crash for the purposes of this 

analysis. 

Vehicle Descriptors 

Four descriptors were used to define the 

simulated vehicle in this analysis. The width 

of the vehicle was assumed to be 6.0 feet for 

this analysis. The distance that the vehicle 

backed up during each backing trial was 

determined by a random draw from a threeparameter Weibull probability distribution 

for distance backed that was based on data 

from the ‘‘On-Road Study of Drivers’ Use of 

Rearview Video Systems’’ study.115 To 

simplify the analysis this simulation 

assumed that the vehicle backed up at a 

constant speed based on a random draw from 

a three-parameter Weibull probability 

distribution also based on NHTSA’s research 

data.116

Since backing maneuvers frequently 

involve turning, any backing trial more than 

25 feet long was assumed to possibly include 

a turn. To determine whether the vehicle 

turned to the left, went straight, or turned to 

the right during each backing trial, a 

uniformly distributed random number was 

drawn. There was a 40 percent probability of 

a left turn, a 40 percent probability of a right 

turn, and a 20 percent probability of a no 

turn. The turn, if there was one, did not 

commence until after 25 feet of backing or 30 

feet from the end of the back, whichever was 

greater. Once turning commenced the rear 

bumper of the vehicle traveled around a 20 

foot radius circle. Since the maximum 

distance in the turn was 30 feet, the angle 

which the vehicle turned through ranged 

from 0 to 85.9 degrees (1.5 radians). 

Pedestrian Descriptors 

The pedestrian was modeled in the 

horizontal plane as a circle of radius 0.375 

feet. To simplify the analysis, the pedestrian 

was assumed to move at constant speed and 

direction. The angle of pedestrian travel was 

determined by a random draw from a 

uniform probability distribution extending 

from ¥180.0 to +180.0 degrees. Walking 

speed was determined by a random draw 

from a triangular probability distribution 

ranging from 0.0 to 5.0 mph. 

To define the position of the pedestrian 

behind the vehicle, axes were assigned to the 

grid. An X axis was set up pointing straight 

back along the longitudinal centerline of the 

vehicle with its origin at the rear bumper of 

the vehicle. A Y axis was set up pointing 

along the (assumed straight) rear edge of the 

rear bumper with its origin at the center of 

the rear bumper. Positive Y values were on 

the driver’s side of the vehicle. The 

pedestrian was always started at the center of 

one of the 1-foot grid squares. Therefore, the 

initial positions of the pedestrian, in both X 

and Y, were always at a half foot mark. All 

possible initial pedestrian positions were 

simulated. Therefore, the initial pedestrian X 

positions ranged from 0.5 to 49.5 feet in 

1.0-foot increments. Similarly, the initial 

pedestrian Y positions ranged from ¥9.5 to 

9.5 feet also in 1.0-foot increments. 

Additional Simulation Information 

As was previously mentioned, a total of 

1,000,000 Monte Carlo simulation trials were 

run with the pedestrian initially in the center 

of each square. Each trial simulated 60.0 

seconds of time unless the pedestrian 

collided with the vehicle or the vehicle 

completed its movement first. Actual backing 

events do not last for 60.0 or more seconds. 

The longest backing event out of the 6,185 in 

the ‘‘On-Road Study of Drivers’ Use of 

Rearview Video Systems’’ study 117 data set 

was 52.8 seconds long. However, for the 

simulation, both the backing distance and 

average backing speed were determined 

independently of each other from Weibull 

probability distributions. This is actually not 

correct; statistical analyses of the ‘‘On-Road 

Study of Drivers’ Use of Rearview Video 

Systems’’ study 118 data set indicates that for 

real driving, as backing distance increases so 

does average backing speed. However, it was 

decided to accept the independence of the 

backing distance and average backing speed 

so as to simplify the simulation. As a result, 

1.1 percent of all simulated backing trials had 

not been completed after 60.0 seconds of 

simulation. For the purposes of this analysis 

it was decided that the normalization process 

would probably adequately account for not 

otherwise dealing with this issue. 

A count was made of all trials for which 

the pedestrian collided with the rear bumper 

of the vehicle. If the pedestrian collided first 

with either the front or sides of the vehicle, 

then this was not counted as a backing 

collision. 

After completion of the simulation for all 

grid squares, a normalization of the backing 

crash counts for each grid square was 

performed. The normalization converted 

each grid square’s crash count into its 

probability of crash relative to the probability 

of crash for the grid squares for which a crash 

was most likely to occur. The grid squares for 

which a crash was most likely to occur were 

the two directly behind the bumper in the 

center of the vehicle, i.e., the grid squares at 

(0.5 ft, 0.5 ft) and at (0.5 ft, ¥0.5 ft). The 

relative probability of crash for these two grid 

squares was set to 1.0. For all other grid 

squares, the crash count was divided by the 

crash count for grid square (0.5, 0.5). Note 

that due to left-right mirroring, the grid 

squares at (0.5, 0.5) and at (0.5, ¥0.5) both 

had the same crash counts. This resulted in 

a probability of crash relative to the 

probability of crash for the grid squares at 

(0.5, 0.5) and at (0.5, ¥0.5). Since all grid 

squares were subjected to the same 

simulation imperfections, this first 

normalization was expected to reduce the 

impact of these imperfections of the 

simulation results. 

Figure 1 of this notice summarizes the 

calculated relative crash risk for each grid 

square. Note that the white shaded area does 

not have a zero backover risk; it merely has 

a low (less than 12.5 percent of the 

maximum) risk. 

This analysis shows that the probability of 

crash decreases rapidly as the pedestrian’s 

initial location is moved back, further away, 

from the rear bumper of the vehicle. There 

are substantial side lobes, giving pedestrians 

a reasonable chance of being hit even though 

they were not initially directly behind the 

vehicle. 

Appendix B—Method for On-Road 

Study of Drivers’ Use of Rearview 

Video Systems 

Drivers’ use of rearview video systems was 

observed during staged and naturalistic 

backing maneuvers to determine whether 

Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 9519 

119Mazzae, E.N., Barickman, F.S., Baldwin, 

G.H.S., and Ranney, T.A. (2008). On-Road Study of 

Drivers’ Use of Rearview Video Systems (ORSDURVS). National Highway Traffic Safety 

Administration, DOT 811 024. 

120Mazzae, E.N., Light Vehicle Rear Visibility 

Assessment, DOT HS 810 909, September 2008. 

NHTSA’s visual target for this test was a traffic cone 

with a reflector atop; its height is representative of 

a 1-year-old child. 

drivers look at the RV display during backing 

and whether use of the system affects backing 

behavior.119 Thirty-seven test participants, 

aged 25 to 60 years, were comprised of 

twelve drivers of RV-equipped vehicles, 

thirteen drivers of vehicles equipped with an 

RV system and a rear parking sensor system, 

and twelve drivers of vehicles with no 

backing aid system. All three system 

conditions were presented using original 

equipment configurations of the 2007 Honda 

Odyssey minivan. All participants had 

driven and owned a 2007 Honda Odyssey 

minivan as their primary vehicle for at least 

6 months. Participants were not aware that 

the focus of the study was on their behavior 

and performance during backing maneuvers. 

Participants visited a test lab to have 

unobtrusive video and other data recording 

equipment installed in their personal 

vehicles, and for a brief test drive. 

Participants then drove their vehicles for a 

period of 4 weeks in their normal daily 

activities while backing maneuvers were 

recorded. At the end of 4 weeks, participants 

returned to the research lab to have the 

recording equipment removed. Then, 

participants took a second test drive, 

identical to the first, except that when 

backing out of the garage bay, an unexpected 

36-inch-tall obstacle consisting of a twodimensional photograph of a child appeared 

behind the vehicle. 

Appendix C—Details Regarding 

Development of a Possible 

Countermeasure Application Threshold 

Based on Rear Blind Zone Area 

To begin to investigate what this threshold 

value might be, NHTSA plotted the average 

backing and backover rates versus the directview rear blind zone areas for 28 vehicles, as 

shown in Figure C–1. Several options for 

setting a threshold were examined. One 

option could be to choose the natural break 

point on the plotted curve at which the slope 

dramatically increases for crash rate as a 

function of direct-view rear blind zone area. 

This option results in vehicles with the 

poorest rear visibilities that contribute 

disproportionately to backover crashes being 

affected. One observation with this option is 

that the worst offenders for rear visibility 

would be captured, but a large percentage of 

overall backover crashes would not be 

addressed, such as those involving small 

pickups. 

Appendix D—Results for Analysis of 

Correlation Between Rear Blind Zone 

Area Measurement Field Size and 

Backing Crashes 

To support the determination of the 

dimensions of the rear visibility 

measurement field, NHTSA’s measured rear 

blind zone area data for a variety of vehicles 

were compared with backing crashes for 

those vehicles. Data analysis was performed 

to assess the correlation between vehicles’ 

rear blind zone areas measured using a 50th 

percentile male driver and backing crash data 

for 21 vehicles.120 Complete results of this 

analysis for a portion of the field sizes 

assessed are summarized in Table D–1. 


EP04MR09.014</GPH>
9520 Federal Register / Vol. 74, No. 41 / Wednesday, March 4, 2009 / Proposed Rules 

TABLE D–1—CORRELATION BETWEEN HUMAN-BASED REAR BLIND ZONE AREA MEASURED OVER VARIOUS FIELD SIZES

AND BACKING CRASHES

[Sorted by correlation coefficient] 

Measurement field dimensions 

(width by length) 

Correlation 

coefficient 

Probability 

occurred by 

chance 

50W × 10L ............................................................................................................................................................... 0.60117 0.0039 

40W × 10L ............................................................................................................................................................... 0.60117 0.0039 

30W × 10L ............................................................................................................................................................... 0.58233 0.0056 

30W × 50L ............................................................................................................................................................... 0.55212 0.0095 

40W × 40L ............................................................................................................................................................... 0.54681 0.0103 

30W × 40L ............................................................................................................................................................... 0.53635 0.0122 

50W × 40L ............................................................................................................................................................... 0.53113 0.0132 

20W × 40L* .............................................................................................................................................................. 0.52621 0.0143 

50W × 50L** ............................................................................................................................................................ 0.52375 0.0148 

20W × 50L ............................................................................................................................................................... 0.52367 0.0148 

40W × 30L ............................................................................................................................................................... 0.52341 0.0149 

50W × 60L ............................................................................................................................................................... 0.51360 0.0172 

30W × 30L ............................................................................................................................................................... 0.51227 0.0176 

60W × 50L ............................................................................................................................................................... 0.51891 0.0159 

50W × 30L ............................................................................................................................................................... 0.50641 0.0192 

60W × 60L ............................................................................................................................................................... 0.50403 0.0198 

40W × 20L ............................................................................................................................................................... 0.48513 0.0258 

20W × 30L ............................................................................................................................................................... 0.48117 0.0272 

50W × 20L ............................................................................................................................................................... 0.47920 0.0280 

70W × 70L ............................................................................................................................................................... 0.47331 0.0302 

70W × 80L ............................................................................................................................................................... 0.45159 0.0399 

70W × 90L ............................................................................................................................................................... 0.43665 0.0478 

20W × 20L ............................................................................................................................................................... 0.39522 0.0762 

10W × 40L ............................................................................................................................................................... 0.35315 0.1163 

10W × 10L ............................................................................................................................................................... 0.27903 0.2206 

* This measurement field size was indicated by pedestrian backover crash risk simulation as encompassing pedestrian locations at which risk 

of a backing crash was 20 percent or higher. 

** Blind zone area measured over a field this size was found by preliminary analysis of laser-based measurement data to be well correlated 

with backing crashes. 

[FR Doc. E9–4500 Filed 2–27–09; 11:15 am] 

BILLING CODE 4910–59–P