[Federal Register Volume 74, Number 123 (Monday, June 29, 2009)]
[Proposed Rules]
[Pages 30993-30996]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E9-15314]



National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. NHTSA-2001-8876]

Federal Motor Vehicle Safety Standard No. 108; Lamp, Reflective 
Devices and Associated Equipment

AGENCY: National Highway Traffic Safety Administration (NHTSA), DOT.

ACTION: Denial of petition for rulemaking.


SUMMARY: This document denies a petition for rulemaking submitted by 
General Motors on December 20, 2001. The petitioner requested that the 
agency amend the Federal motor vehicle safety standard (FMVSS) on 
lamps, reflective devices, and associated equipment to require the 
installation of daytime running lamps on passenger cars, multipurpose 
passenger vehicles, trucks, and buses that have a gross vehicle weight 
rating under 4,536 kilograms (10,000 lbs). NHTSA has reviewed the 
petition and performed an extensive analysis of real world crash data. 
Based on the results of our study we were unable to find solid evidence 
of an overall safety benefit associated with daytime running lamps and 
are therefore denying the petition for rulemaking. The agency maintains 
its neutral position with respect to the safety benefits from the use 
of daytime running lamps.

FOR FURTHER INFORMATION CONTACT: For non-legal issues, you may call Mr. 
Markus Price, Office of Crash Avoidance Standards (Phone: 202-366-0098; 
FAX: 202-366-7002).
    For legal issues, you may call Mr. Ari Scott, Office of the Chief 
Counsel (Phone: 202-366-2992; FAX: 202-366-3820).
    You may send mail to these officials at: National Highway Traffic 
Safety Administration, 1200 New Jersey Avenue, SE., Washington, DC 


Table of Contents

I. Summary
II. Background
III. Petition
IV. Agency Analysis and Decision
    a. NHTSA Studies and Comparison
    b. Differences in Statistical Methodology
V. Conclusion

I. Summary

    This document denies a 2001 petition from General Motors (GM) 
requesting that the National Highway Traffic Safety Administration 
(NHTSA) mandate the installation of daytime running lamps (DRLs) on all 
vehicles with a gross vehicle weight rating (GVWR) under 4,536 
kilograms (10,000 lbs). The rationale for denying the petition is that, 
overall, studies of the effectiveness of DRLs have not indicated that 
they are an effective means of preventing crashes. While GM presented 
studies that appear to indicate a degree of effectiveness, NHTSA's own 
studies contradict that finding. Furthermore, for reasons described in 
detail below, a careful analysis of the various studies of DRL 
effectiveness indicates flaws in the studies GM cites and that NHTSA 
should place greater weight on its own studies. Given the information 
currently available, the agency has been unable to determine if there 
are any demonstrable safety benefits associated with mandating DRLs, 
and therefore has decided that leaving them as a manufacturer option is 
the best course of action.

II. Background

    Federal Motor Vehicle Safety Standard (FMVSS) No. 108; Lamps, 
reflective devices, and associated equipment, establishes lighting 
requirements for motor vehicles. Daytime Running Lamps (DRLs) are 
steady burning lamps that illuminate when the regular headlamps are not 
required for driving. While FMVSS No. 108 does not require DRLs, it 
does specify requirements that they must meet if a vehicle manufacturer 
voluntarily decides to install them.\1\

    \1\ See 49 CFR 571.108, S7.10.1, Table I-a.

    The requirements for DRLs were first established on January 11, 
1993 in

[[Page 30994]]

response to a petition from General Motors (GM) that asked the agency 
to facilitate the introduction of DRLs on motor vehicles. At that time, 
GM's view was that an amendment ``would allow manufacturers to install 
DRLs on new vehicles without being in violation of the multitude of 
State laws'' which at that time had ``the unintended effect of 
prohibiting them.'' Also, GM did not believe that there was 
justification for mandating DRLs as standard equipment because there 
was not yet evidence of a ``national safety need'' in the United 
States. As a result of GM's petition, FMVSS No. 108 was amended to 
permit, but not require, DRLs that comply with various marking and 
performance requirements.\2\

    \2\ See 59 FR 3501 January 11, 1993.

III. Petition

    On December 20, 2001, GM petitioned the agency requesting that DRLs 
be made required equipment on passenger vehicles, trucks and buses that 
have a gross vehicle weight rating under 4,536 kilograms (10,000 lbs). 
In support of its petition, GM provided information from a study that 
reported a 5 percent decrease in daytime multiple vehicle crashes and a 
9 percent reduction in vehicle to pedestrian crashes.\3\ GM claimed 
that this report ``demonstrates that DRLs are preventing crashes and 
injuries, and saving lives.'' The data supporting this study were 
collected in 12 States from the years 1994 to 1997, using vehicle 
registration as a measure of exposure, and the ratio of crash rates 
estimated by the Poisson regression statistical method (described in 
detail below).

    \3\ Docket No. NHTSA-2001-8876-11.

    As an update to the 2000 study, GM most recently sponsored a study 
written by Steffey, Lau, and Ray of Exponent, Inc in 2008.\4\ This 
study examined vehicles manufactured by GM, Saab, Toyota, Subaru, 
Volkswagen and Volvo. Crash data were analyzed from 18 States between 
the years 1996 and 2005. This study used two mathematical methods to 
determine if there was a link between DRLs and crash rates, the ratio 
of odds ratio method and the ratio of crash rates. This study reported 
the impact of DRLs on various types of vehicle crashes including head-
on, rural area, highway, rain/fog, angle, urban area, sideswipe, 
pedestrian, and motorcycle.

    \4\ Docket No. NHTSA-2001-8876-15.

    The Steffey et al. (2008) study reported a statistically 
significant reduction in crashes associated with DRLs. For passenger 
cars, it reported a reduction in daytime head-on multi-vehicle crashes 
of 12.35 percent using the ratio of crash rates method. This study also 
reported a significant reduction in rural area daytime multi-vehicle 
crashes of 9.1 percent for passenger cars using this method.\5\ Similar 
results were reported for light trucks. Similar to the 2001 GM study, 
this study reported a 5 percent decrease in daytime multiple vehicle 
crashes, but contrary to the 2001 study, a non-significant increase in 
vehicle to pedestrian crashes of 2.5 was observed. No statistically 
significant results were found for fatal crashes.

    \5\ Docket No. NHTSA-2001-8876-15 Steffey et al., p. 21.

    This study also analyzed the data using the ratio of odds ratio 
technique. GM stated that this methodology produced findings that 
correlated DRLs with a reduction in certain crash types. However, 
NHTSA's analysis found, with regard to the overall crash rates 
experienced by vehicles equipped with DRLs, the Steffey et al. study's 
analysis using the ratio of odds ratios method did not produce a 
statistically significant decrease in the crash rates of those 

    \6\ Docket No. NHTSA-2001-8876-15 Steffey et al. page 38.

IV. Discussion and Analysis

    After carefully reviewing the data in GM's petition, NHTSA has come 
to the conclusion that the evidence linking DRLs to lower incidents of 
crashes is not persuasive. To begin, NHTSA believes that one of the 
statistical techniques used in the two GM studies, the ratio of crash 
rates method, is less effective in this case than the ratio of odds 
ratio method used in the three NHTSA studies (to be fair, this 
methodology was also employed in the Steffey et al. study). 
Additionally, certain correlations in the GM study raise questions as 
to the validity of its findings. Contrary to this, NHTSA's studies do 
not show that DRLs are an effective means of crash avoidance. Given 
these issues, NHTSA does not believe that the case has been made to 
incorporate a change to require DRLs.

A. NHTSA Studies and Comparison

    In 2000, NHTSA published a study that examined the effectiveness of 
DRLs installed on passenger cars manufactured in the 1990s.\7\ In that 
study, no statistically significant results were found using the ratio 
of odds ratio method. In 2004, NHTSA again reported on the 
effectiveness of DRLs on crashes within the U.S.\8\ Again, using a 
broader data set and a different control group, no results using the 
ratio of odds ratio method produced statistical significance.

    \7\ DOT HS 808 645 Table 24 & 25 Available at http://www.nhtsa.dot.gov/people/ncsa/pdf/DRL7_RPT.pdf.
    \8\ DOT HS 809 760 Appendix B Available at http://www-nrd.nhtsa.dot.gov/Pubs/809760.PDF.

    In 2008, NHTSA completed a new study on the effectiveness of 
DRLs.\9\ The data source is FARS (2000-2005), and State data from 9 
States (2000-2005). The results of this NHTSA study (2008) are 
inconclusive regarding overall DRL effectiveness. When both light truck 
and cars are evaluated together, the result of DRL installation is a 
non-statistically significant decrease in two vehicle, all severity 
crashes of 0.3 percent (-2.5-3.1, 0.95 confidence). A statistically 
significant decrease of 5.7 percent (0.7-10.7, 0.95 confidence) in two 
vehicle type crashes for light trucks is somewhat offset by a non-
significant 2 percent (-5.4-1.4, 0.95 confidence) increase in passenger 
car crashes of the same type and severity. Further complicating 
attempts to find a definitive pattern of safety impact that DRLs have, 
this study finds a non-significant increase of 12.2 percent (-50.1-
25.7, 0.95 confidence) in light truck-motorcycle crashes. Contrarily, 
it also reports that a non-significant decrease of 1.2 percent (-18.5-
20.9, 0.95 confidence) is observed for passenger cars of the same crash 
type. Continuing, this study was also unable to find a clear pattern of 
effectiveness between States. An overview of the results finds some 
positive and some negative results depending on crash type and crash 
severity. When all crashes are considered, a non-significant decrease 
of 0.1 percent is observed, demonstrating the overall safety benefits 
of DRLs in this study are inconclusive.

    \9\ HS 811 029.

    The agency is aware of some groups' concerns that DRLs may have a 
detrimental impact on motorcycle safety. The concern is that as 
motorcycles have historically been the only class of vehicles using 
DRLs, as other vehicle classes begin to use DRLs the unique conspicuity 
provided to motorcycles by DRLs will be diminished. Neither the GM, nor 
the agency's studies are able to establish new evidence with respect to 
this concern. Therefore, the potential ``masking effect'' is still 
unknown and was not considered in this denial notice analysis.
    The agency believes that the result derived based on the ratio of 
odds ratios are more plausible and defendable than those based on crash 
rates used in GM's study. The Steffey et al. study found a

[[Page 30995]]

4.28 percent decrease in nighttime multi-party car crashes as a result 
of DRL installation. It also found a 3.67 percent decrease in single 
vehicle light truck crashes. Additionally, the report found that DRLs 
would reduce nighttime fatal crashes by 11.4 percent for passenger cars 
and daytime single-vehicle crashes by 9.4 percent for light trucks.\10\ 
These results cast doubt on the validity of the GM study because we do 
not believe these crash types are plausibly affected by DRL 
installation. The authors claim these numbers ``serve as useful control 
groups and benchmarks for comparison.'' \11\ The agency respectfully 
disagrees, and believes this may demonstrate the lack of control for 
changes that may have occurred during the study period. Another 
limitation regarding this GM study is the different time period for 
which vehicle registration was recorded compared to the times that the 
crashes occurred. The registration numbers were recorded as a snapshot 
in time on July first, but the crashes occurred throughout the entire 
year. This time difference may cause inaccuracies in the number of 
vehicles in the exposure group.

    \10\ Docket No. NHTSA-2001-8876-15 Steffey et al., p. 24-25.
    \11\ Docket No. NHTSA-2001-8876-15 Steffey et al. p. 20.

B. Differences in Statistical Methodology

    As discussed above, numerous studies exist that attempt to quantify 
the crash risk relative to the installation of DRLs. Among these 
studies, various statistical techniques have been used for determining 
the effectiveness in real world crashes, including the ratio of odds 
ratios method (used in the NHTSA studies), and the ratio of crash rates 
method (used in the GM studies). NHTSA believes that the ratio of odds 
ratios is the most effective means for the analysis in these studies.
    The primary statistical technique used in the studies submitted by 
GM in support of its petition is the ratio of crash rates method. This 
was used in the 2001 GM study, and was also used in certain parts of 
the 2008 Steffey et al. study. This technique compared the ratio of 
crashes to the number of vehicles of that type registered. This 
collision rate is calculated and compared for both vehicles with DRLs 
and for vehicles without DRLs. This comparison reportedly represents 
the effectiveness of the DRL. This is mathematically represented as 

    Continuing, this expression is modeled using a Poisson regression 
model to estimate the overall DRL effect across all model pairs. 
Because this method uses vehicle registration as the measure of 
exposure, it may not reflect the actual on-road exposure of vehicles in 
use that, in actuality, may be involved in a crash. For example, this 
methodology would assign equal weight to a vehicle driven five miles 
per day as to a vehicle driven 25 miles per day, despite the fact that 
the latter vehicle is far more exposed to the risk of a crash.
    The ratio of odds ratios method, which was used in NHTSA's studies 
and in some parts of the Steffey et al. study, avoids using vehicle 
registration as a method of exposure. This method compares the ratio of 
target crashes in the daytime with control crashes in the daytime. It 
continues by calculating the ratio of target crashes at night compared 
to the control crashes at night. The ratio of these ratios is then 
considered the odds of a vehicle becoming involved in a DRL relevant 
crash. This ratio is calculated for both a group of DRL-equipped 
vehicles, and for a group of vehicles which do not have DRLs installed. 
A comparison of the two groups' odds then determines the effectiveness 
of the DRL. This method is demonstrated as follows:

                          DRL-Equipped Vehicles
         Light condition            Target crashes      Control crashes
Daytime.........................  N1................  N2.
Nighttime.......................  N3................  N4.

                            Non-DRL Vehicles
         Light condition            Target crashes      Control crashes
Daytime.........................  N5................  N6.
Nighttime.......................  N7................  N8.

                                                      [GRAPHIC] [TIFF OMITTED] TP29JN09.012

[[Page 30996]]

    The value of R represents the relative odds of daytime target 
crashes involvements between DRL-equipped vehicles and non-DRL 
vehicles. The agency believes the ratio of odds ratio is the optimal 
method because it has a strong confounding-factor-control ability. With 
regard to the previous example, the ratio of odds ratios would factor 
in a higher expected crash rate for the vehicle driven 25 miles per day 
than the vehicle driven five.
    The ratio of odds ratios avoids using crash rates because the true 
exposure data generally do not exist. In GM's case, with regard to the 
portion of the study that utilized the ratio of crash rates method, 
vehicle registrations were used as the exposure data. However, 
registration data do not differentiate driving between DRL and non-DRL 
vehicles. They do not separate daytime and nighttime driving. 
Consequently, vehicle registrations are not considered to be an 
appropriate exposure measure for a DRL study. The contradicting results 
from the GM study demonstrate this. In contrast, the ratio of odds 
ratios method compares the ratio of target crashes (DRL-relevant) to 
control crashes (non DRL-relevant) in the daytime.
    The Steffey et al. study incorporated both of the methodologies in 
arriving at its conclusions. Using the ratio of crash rates method, the 
study found an overall decrease in crash rates of 4.61 percent, which 
was noted as statistically significant.\12\ However, using the ratio of 
odds ratios method, the same report found a non-significant decrease in 
the crash rates of 1.36 percent.\13\ Given the significant divergence 
in results from the different methodologies, we feel that the results 
from the ratio of crash rates methodology should be assigned less 
weight in NHTSA's analysis of the safety effect of DRLs.

    \12\ Steffey et al., p. 34.
    \13\ Steffey et al., p. 38.

V. Conclusion

    The agency's 2008 DRL study is a more robust study than previous 
attempts by the agency to quantify the effectiveness of DRLs. This 
newest study was unable to find solid evidence of overall safety 
benefits associated with DRLs installed on passenger vehicles using the 
ratio of odds ratio statistical technique. While DRLs may be beneficial 
for certain scenarios, the agency has been unable to document overall 
safety benefits due to DRL installation which could serve as a basis 
for mandating them. NHTSA is therefore denying this petition from GM. 
However, the agency is willing to re-examine the DRL issue if 
additional data is presented demonstrating overall safety benefits. Any 
such study should consider using the ratio of odds ratios technique as 
used in the latest NHTSA study, or provide compelling evidence that an 
alternative technique is superior at predicting the effectiveness of 
DRLs. In the meantime, the agency remains neutral with respect to a 
policy regarding the inclusion of DRLs in vehicles. Although we do not 
find data that provides a definitive safety benefit that justifies 
Federal regulation, we are not making recommendations that vehicle 
manufacturers should change their policies regarding DRLs. 
Manufacturers should continue to make individual decisions regarding 
DRLs in their vehicles.

    Authority: 49 U.S.C. 322, 30111, 30115, 30117 and 30166; 
delegation of authority at 49 CFR 1.50.

    Issued: June 23, 2009.
Nathaniel Beuse,
Director, Office of Crash Avoidance Standards.
[FR Doc. E9-15314 Filed 6-26-09; 8:45 am]