[Federal Register Volume 63, Number 169 (Tuesday, September 1, 1998)]
[Rules and Regulations]
[Pages 46389-46394]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-23410]


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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

23 CFR Part 1340

[Docket No. NHTSA-98-4280]
RIN 2127-AH46


Uniform Criteria for State Observational Surveys of Seat Belt Use

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

ACTION: Interim final rule; request for comments.

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SUMMARY: This document establishes uniform criteria for State seat belt 
use surveys that are to be conducted in connection with a new Federal 
grant program. Section 157 of Title 23, United States Code, directs the 
Secretary of Transportation to allocate funds to States that achieve a 
seat belt use rate that exceeds, for the past two years, the national 
average use rate, or that exceeds the highest seat belt use rate 
achieved by the State in certain designated previous years. For 
calendar years 1998 through 2001, the new law requires the seat belt 
use rate submitted by the States to be consistent with measurement 
criteria established by the Secretary. This document sets forth the 
criteria to be used by the States to determine their seat belt use 
rates under this program, starting with surveys conducted in calendar 
year 1998. These uniform criteria replace the Guidelines for State 
Observational Surveys of Safety Belt and Motorcycle Helmet Use, which 
are rescinded by this document.

DATES: This interim final rule is effective on September 1, 1998. 
Comments concerning this rule are due no later than January 29, 1999.

ADDRESSES: Comments should refer to the docket number set forth above 
and be submitted in writing to the Administrator, National Highway 
Traffic Safety Administration, Room 5220, 400 Seventh Street, SW, 
Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: The following persons at the National 
Highway Traffic Safety Administration, 400 Seventh Street, SW, 
Washington, DC 20590: For program issues, Joan Catherine Tetrault, 
State and Community Services, NSC-01, (202) 366-2674; For legal issues, 
John Donaldson, Office of the Chief Counsel, NCC-30, (202) 366-1834.

SUPPLEMENTARY INFORMATION:

New Seat Belt Incentive Grant Program

    Section 1403 of the recently enacted Transportation Equity Act for 
the 21st Century (Pub. L. 105-178) added a new Section 157 to Title 23 
of the United States Code (replacing a predecessor Section 157 ). The 
new section authorizes a State seat belt incentive grant program 
covering fiscal years 1999 through 2003. Under this program, the 
Secretary of Transportation is directed to allocate funds to the States 
(beginning in fiscal year 1999) based on their seat belt use rates. 
Today's rule promulgates the Uniform Criteria for State Observational 
Surveys of Seat Belt Use (hereafter, Uniform Criteria) to provide 
guidance to the States on the seat belt use rate information to be 
submitted

[[Page 46390]]

under this new program for calendar year 1998 and beyond.
    Section 157 requires the Secretary to allocate funds to States that 
achieve a seat belt use rate in the preceding two years that is higher 
than the national average use rate or, failing that, a seat belt use 
rate that is higher than the highest seat belt use rate achieved by the 
State during specified previous calendar years. (Section 157 contains 
another provision for allocation of grant funds, based on innovative 
projects, but that provision is not addressed in today's notice.) In 
order to make the calculations necessary to allocate funds under this 
provision, State seat belt use rate information extending back to 
calendar year 1996 is needed. For calendar years 1996 and 1997, seat 
belt use rate information submitted by the States is required to be 
weighted by the Secretary to ensure national consistency in methods of 
measurement. Beginning in calendar year 1998, States must measure seat 
belt use rates following criteria established by the Secretary, to 
ensure that the measurements are ``accurate and representative.'' In 
accordance with that mandate, this interim final rule establishes 
uniform criteria for States to follow in conducting surveys of seat 
belt use, starting with surveys conducted in calendar year 1998. 
(Details concerning the procedures the agency will follow in evaluating 
and adjusting seat belt use rate information to ensure that it is 
accurate and representative and in making the allocation of funds will 
be published in the near future in a separate Federal Register 
document.)

State Seat Belt Use Surveys

    The Uniform Criteria published today incorporate, in large part, 
the Guidelines for State Observational Surveys of Safety Belt and 
Motorcycle Helmet Use (57 FR 28899, June 29, 1992) (hereafter, 
Guidelines) that relate to seat belts. However, the new criteria differ 
in one important respect. Section 157 requires the determination of 
seat belt use rate to be based on ``passenger motor vehicles,'' a 
category that includes passenger cars, pickup trucks, vans, minivans, 
and sport utility vehicles. Consequently, the criteria incorporate the 
statutory requirement that measurements include the seat belt use rate 
of occupants of these vehicles. A number of States have not included 
these vehicles in past seat belt surveys.
    Another, more minor respect, in which these Uniform Criteria differ 
from the Guidelines, is that the observation of child restraint use is 
not included in the survey. The agency has removed this requirement 
because Section 157 does not include child restraint devices within the 
definition of seat belts.
    Section 157 requires that measurements of seat belt use rates be 
``accurate and representative.'' Consequently, these Uniform Criteria 
clarify the Guidelines in other respects. The agency has made clear 
that the surveys must include observation of both drivers and front 
seat outboard passengers (not simply consider them ``eligible'' for 
observation, as provided in the Guidelines). In addition, measurements 
of seat belt use must be taken completely within the calendar year for 
which the seat belt use rate is reported. Finally, beginning with 
surveys conducted during calendar year 1999, both in-state and out-of-
state vehicles must be counted, to improve the representativeness of 
measurements. This latter requirement is being phased in next year to 
provide the States necessary flexibility, in view of time constraints 
associated with the late enactment of TEA-21. These clarifications, 
together with other procedures the agency expects to publish in the 
near future in the Federal Register (further discussed below), will 
ensure consistency and fairness in the allocation of funds.
    NHTSA is recommending, in this notice, that seat belt use data be 
collected so as to enable separate identification for passenger cars 
and other covered vehicles, and separate identification for drivers and 
front-seat outboard passengers within these vehicle groups. NHTSA 
believes that this separation, although not a requirement, will produce 
useful information for the States, the agency, and others to evaluate 
trends in seat belt use.
    In other particulars, these Uniform Criteria track the Guidelines. 
For example, the important requirement that surveys have a probability-
based design has been retained. So, too, have the requirements that 
data be collected through direct observation of seat belt use; that the 
relative error of the estimate of seat belt use not exceed five 
percent; that counties or other primary sampling units totaling at 
least 85 percent of the State's population be eligible for inclusion in 
the sample; and that all daylight hours for all days of the week be 
eligible for inclusion in the sample. The new criteria continue to 
require all sample design, data collection and estimation procedures to 
be well documented. The appendix, containing a sample design that 
satisfies these criteria, is also retained for useful reference. These 
and other provisions, continued in today's rule, were previously 
published for comment in connection with the Guidelines.
    In a separate Federal Register document to be published in the near 
future, the agency will explain the process it plans to follow in 
reviewing and evaluating surveys submitted by the States in accordance 
with today's rule, in determining the national average seat belt use 
rate, and in making allocations of funds. In that document, the agency 
may consider applying adjustment factors to survey information 
submitted by the States before making allocations of funds, to further 
ensure that seat belt use measurements are accurate and representative.

Assistance in Developing Surveys

    The agency stands ready to assist States in their efforts to 
develop probability-based observational surveys that satisfy the 
requirements of Section 157 and these uniform criteria. Each NHTSA 
Regional Office has a data contractor available to provide technical 
assistance to the States upon request. States that have not yet 
conducted surveys for calendar year 1998 that satisfy these criteria 
may wish to submit proposed survey designs to NHTSA for review, in 
order to verify that the survey design satisfies these new criteria. 
This may be especially helpful for States that have not received 
approval of the similar surveys that were required for award of grant 
funds under the Guidelines.

State Eligibility for Grant Funds

    The Uniform Criteria published today are effective immediately. 
States must become promptly familiar with these criteria because they 
apply to surveys required to be conducted during the current calendar 
year. States that fail to conduct a calendar year 1998 survey in 
accordance with these criteria will not be eligible, during fiscal year 
2000 and possibly beyond, for Section 157 grant funds that are based on 
the submission of seat belt use rate information.
    The Uniform Criteria are limited in scope to the substantive 
requirements related to State observational surveys. The agency expects 
to publish in the near future, in a separate Federal Register document, 
details concerning the procedures the agency will follow in evaluating 
seat belt use rate information and in making the allocation of funds. 
However, in order to provide the States with as much planning 
flexibility as possible in light of the imminence of the requirements 
concerning calendar year 1998 surveys, brief information about 
submission and review procedures is provided here.

[[Page 46391]]

    The agency anticipates that review procedures for surveys will 
remain essentially unchanged from those that applied under the 
Guidelines. Specifically, States seeking to qualify for an allocation 
of Section 157 funds based on their seat belt use rate will submit the 
documentation of their survey design described under the 
``Documentation'' section of these uniform criteria for review by the 
agency. Based on the documentation submitted, NHTSA will determine 
whether the survey meets the requirements of these criteria.
    Pending the publication of specific procedural guidance in the 
Federal Register, States that have not yet conducted a survey for 
calendar year 1998 are encouraged to seek pre-approval of their survey 
documentation by NHTSA. States that have conducted a survey for 
calendar year 1998 are also encouraged to submit survey documentation 
for review by NHTSA, to confirm that the survey they have conducted 
does, in fact, conform to these criteria. This will avoid the situation 
where non-compliance is discovered too late to conduct another survey 
during calendar year 1998.

Previous Survey Guidelines Rescinded

    With the publication of these Uniform Criteria for State 
Observational Surveys of Seat Belt Use, the agency is simultaneously 
rescinding the Guidelines. The agency published these latter guidelines 
to describe survey requirements for States seeking to receive grants 
under Section 153 of Title 23, United States Code, a grant program 
which is no longer funded.

Regulatory Analyses and Notices

Executive Order 12612 (Federalism)

    This action has been analyzed in accordance with the principles and 
criteria contained in Executive Order 12612, and it has been determined 
that it does not have sufficient Federalism implications to warrant the 
preparation of a Federalism assessment. While it concerns a new State 
grant program, this action does not impose any major new requirements 
on the States. Rather, it makes minor changes to survey procedures that 
have already been used by many States in a previously authorized grant 
program and for other purposes.

Executive Order 12778 (Civil Justice Reform)

    This rule does not have any preemptive or retroactive effect. It 
merely revises existing requirements imposed on States to reflect the 
statutory requirements of a new grant program. The enabling legislation 
does not establish a procedure for judicial review of final rules 
promulgated under its provisions. There is no requirement that 
individuals submit a petition for reconsideration or pursue other 
administrative proceedings before they may file suit in court.

Executive Order 12866 (Regulatory Planning and Review) and DOT 
Regulatory Policies and Procedures

    This rulemaking action was reviewed under Executive Order 12866, 
``Regulatory Planning and Review.'' The action has been determined to 
be ``significant'' under Executive Order 12866 and under the Department 
of Transportation Regulatory Policies and Procedures because it is 
likely to result in significant economic impacts. A Final Economic 
Assessment (FEA) is being prepared for today's rule and for a companion 
rule, to be published in the near future, that establishes the 
procedures for allocating funds under the grant program authorized by 
23 U.S.C. 157. A copy of the FEA, describing the economic effects in 
detail, will be placed in the docket for public inspection when the 
companion rule is published.
    Following is a summary of the cost and benefit information for this 
rule. The total annual cost of conducting surveys following the 
procedures of this rule (if each State conducted one) is estimated to 
be $1.9 million. A State may be eligible for an allocation of funds 
during each of fiscal years 2000 through 2003 if it conducts a survey 
of seat belt use during each of calendar years 1998 through 2001, in 
accordance with the procedures under this rule. Allocations available 
to the States total $92,000,000 for fiscal year 2000, $102,000,000 for 
fiscal year 2001, and 112,000,000 for each of fiscal years 2002 and 
2003. An allocation totaling $82,000,000 is available for fiscal year 
1999, but that allocation is dependent on criteria other than the 
survey procedures required under this rule. Depending on the results of 
State surveys, some funds may remain unallocated, and will be allocated 
under other procedures. Details of the procedures for allocating all 
funds will be published in another Federal Register document in the 
near future.

Regulatory Flexibility Act

    In compliance with the Regulatory Flexibility Act (5 U.S.C. 601 et 
seq.), the agency has evaluated the effects of this action on small 
entities. We hereby certify that this action will not have a 
significant economic impact on a substantial number of small entities. 
States are the recipients of any funds awarded under the Section 157 
program, and they are not small entities.

Paperwork Reduction Act

    On August 10, 1998, the Department of Transportation submitted an 
emergency processing information collection request (ICR) to the Office 
of Management and Budget (OMB) for review and clearance under the 
Paperwork Reduction Act of 1995 (Pub. L. 104-13, 44 U.S.C. Chapter 35). 
On August 17, OMB approved the request for clearance, assigning the 
collection OMB Clearance No. 2127-0597. The emergency clearance will 
expire on February 28, 1999. Through February 28, 1999, NHTSA is 
authorized to collect 17,942 burden hours from the affected States, the 
District of Columbia, and Puerto Rico.

National Environmental Policy Act

    The agencies have reviewed this action for the purpose of 
compliance with the National Environmental Policy Act (42 U.S.C. 4321 
et seq.), and have determined that it will not have a significant 
effect on the human environment.

Unfunded Mandates Reform Act

    The Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4) requires 
agencies to prepare a written assessment of the costs, benefits and 
other effects of proposed 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. This interim final rule does not meet the 
definition of a Federal mandate, because the resulting annual 
expenditures will not exceed the $100 million threshold.

Interim Final Rule

    This document is published as an interim final rule, without prior 
notice and opportunity to comment. Because this regulation relates to a 
grant program, the requirements of the Administrative Procedure Act 
(APA), 5 U.S.C. 553, are not applicable. Moreover, even if the notice 
and comment provisions of the APA did apply, the agency believes that 
there is good cause for finding that providing notice and comment in 
connection with this rulemaking action is impracticable, unnecessary, 
and contrary to the public interest, since it would delay the 
availability of guidance to States concerning new requirements 
applicable during calendar year 1998. For the same reasons, we have

[[Page 46392]]

determined that notice and an opportunity for comment are not required 
under the Department's regulatory policies and procedures.
    States need this information immediately in order to comply with 
requirements that are applicable to the observational seat belt surveys 
they must conduct during the current calendar year. The statute 
authorizing the grant program to which this interim final rule applies 
(Pub. L. 105-178) was enacted on June 9, 1998, leaving little time for 
States to both become familiar with new requirements that apply to 
these surveys and conduct these surveys before the end of calendar year 
1998. Moreover, for safety and practicability reasons, many States in 
the northern latitudes must conduct surveys before the winter months, 
leaving even less time for these States to meet the new requirements. 
For these reasons, pursuant to 5 U.S.C. 808 (Pub. L. 104-121) (The 
Congressional review provisions of the Small Business Regulatory 
Enforcement Fairness Act), the agency also, for good cause, finds that 
notice and public procedure are impracticable, unnecessary, and 
contrary to the public interest, and, therefore, this rule can be made 
effective upon publication.
    As an interim final rule, this regulation is fully in effect and 
binding upon its effective date. No further regulatory action by the 
agency is necessary to make the rule effective. However, in order to 
benefit from comments which interested parties and the public may have, 
the agency is requesting that comments be submitted to the docket for 
this rule. All comments submitted in response to this rule, in 
accordance with the procedures outlined below, will be considered by 
the agency. Following the close of the comment period, the agency will 
publish a document responding to the comments and, if appropriate, the 
agency will amend the provisions of this rule.

Comments

    The agency is providing a 150-day comment period for interested 
parties to present data, views, and arguments concerning this rule. The 
agency invites comments on the issues raised in this notice and any 
other issues relevant to this action. Comments must not exceed 15 pages 
in length (49 CFR 553.21). This limitation is intended to encourage 
commenters to detail their primary arguments in a concise fashion. 
Necessary attachments may be appended to these submissions without 
regard to the 15-page limit.
    All comments received by the close of business on the comment 
closing date indicated above will be considered and will be available 
for examination in the docket at the above address both before and 
after that date. To the extent possible, comments filed after the 
closing date will also be considered. However, the rulemaking action 
may proceed at any time after that date. Following the close of the 
comment period, the agency will publish a document responding to the 
comments and, if appropriate, the agency will amend the provisions of 
this rule. The agency will continue to file relevant material in the 
docket as it becomes available after the closing date, and it is 
recommended that interested persons continue to examine the docket for 
new material.
    Those persons desiring to be notified of receipt of their comments 
by the docket should enclose a self-addressed, stamped postcard in the 
envelope with their comments. Upon receipt of the comments, the docket 
supervisor will return the postcard by mail.

List of Subjects in 23 CFR Part 1340

    Grant programs--transportation, Highway safety, Intergovernmental 
relations, Reporting and recordkeeping requirements.

    For the reasons set out in the preamble, title 23, chapter III of 
the Code of Federal Regulations is amended as set forth below.
    1. Part 1340 is added to read as follows:

PART 1340--UNIFORM CRITERIA FOR STATE OBSERVATIONAL SURVEYS OF SEAT 
BELT USE

Sec.
1340.1  Purpose.
1340.2  Applicability.
1340.3  Basic design requirements.
1340.4  Population, demographic, and time/day requirements.
1340.5  Documentation requirements.
Appendix A to Part 1340--Sample Design

    Authority: 23 U.S.C. 157; delegation of authority at 49 CFR 
1.50.


Sec. 1340.1  Purpose.

    This part establishes uniform criteria for surveys of seat belt use 
conducted by States under 23 U.S.C. 157.


Sec. 1340.2  Applicability.

    These uniform criteria apply to State surveys of seat belt use, 
beginning in calendar year 1998 (except as otherwise provided in this 
part), and continuing annually thereafter through calendar year 2001.


Sec. 1340.3  Basic design requirements.

    Surveys conducted in accordance with this part shall incorporate 
the following minimum design requirements:
    (a) Probability-based requirement. The sample identified for the 
survey shall have a probability-based design such that estimates are 
representative of safety belt use for the population of interest in the 
state and sampling errors may be calculated for each estimate produced.
    (b) Observational requirement. Minimum requirements include the 
following:
    (1) The sample data shall be collected through direct observation 
of seat belt use on roadways within the State, conducted completely 
within the calendar year for which the seat belt use rate is being 
reported;
    (2) Seat belt use shall be determined by observation of the use or 
non-use of a shoulder belt;
    (3) Observers shall be required to follow a predetermined, clear 
policy in the event that observations cannot be made at an assigned 
site at the specified time (due to heavy rain, construction, safety 
problems, etc.);
    (4) Instructions to observers shall specify which road and which 
direction of traffic on that road are to be observed (observers must 
not be free to choose between roads at an intersection); and
    (5) Observers shall follow clear instructions on how to start and 
end an observation period and how to stop and start observations if 
traffic flow is too heavy to observe all vehicles or if vehicles begin 
moving too quickly for observation (to remove any possible bias, such 
as starting with the next belted driver).
    (c) Precision requirement. The relative error (standard error 
divided by the estimate) for safety belt use must not exceed 5 percent.


Sec. 1340.4  Population, demographic, and time/day requirements.

    Surveys conducted in accordance with this part shall comply with 
the following minimum population, demographic, and time/day 
requirements:
    (a) Population of interest. (1) Drivers and front seat outboard 
passengers in passenger motor vehicles (passenger cars, pickup trucks, 
vans, and sport utility vehicles) must be observed in the survey. (Only 
overall restraint use for the population of interest is required. 
However, in order to assist in the evaluation of trends, it is 
recommended that data be collected in such a way that restraint use 
estimates can be reported separately for passenger cars and other

[[Page 46393]]

covered vehicles, and separately for drivers and front-seat outboard 
passengers within those vehicle groups.)
    (2) Surveys conducted during calendar year 1998 shall be deemed to 
comply with paragraph (a)(1) of this section if passenger motor 
vehicles registered in-State are included in the survey. For surveys 
conducted during calendar year 1999 and thereafter, passenger motor 
vehicles registered both in-state and out-of-state must be included in 
the survey.
    (b) Demographics. Counties, or other primary sampling units, 
totaling at least 85 percent of the State's population must be eligible 
for inclusion in the sample. States may eliminate their least populated 
counties, or other primary sampling units, to a total of fifteen 
percent or less of the total State population, from the sampling frame.
    (c) Time of day and day of week. All daylight hours for all days of 
the week must be eligible for inclusion in the sample. Observation 
sites must be randomly assigned to the selected day-of-week/time-of-day 
time slots. If cluster sampling is used, assignment of sites and times 
within clusters must be random.


Sec. 1340.5  Documentation requirements.

    All sample design, data collection, and estimation procedures used 
in State surveys conducted in accordance with this part must be well 
documented. At a minimum, the documentation must:
    (a) For sample design--
    (1) Define all sampling units, with their measures of size;
    (2) Define what stratification was used at each stage of sampling 
and what methods were used for allocation of the sample units to the 
strata;
    (3) Explain how the sample size at each stage was determined;
    (4) List all samples units and their probabilities of selection; 
and
    (5) Describe how observation sites were assigned to observation 
time periods.
    (b) For data collection--
    (1) Define an observation period;
    (2) Define an observation site and what procedures were implemented 
when the observation site was not accessible on the date assigned;
    (3) Describe what vehicles were observed and what procedures were 
implemented when traffic was too heavy to observe all vehicles; and
    (4) Describe the data recording procedures.
    (c) For estimation--
    (1) Display the raw data and the weighted estimates;
    (2) For each estimate, provide an estimate of one standard error 
and an approximate 95 percent confidence interval; and
    (3) Describe how estimates were calculated and how variances were 
calculated.

Appendix A to Part 1340--Sample Design

    Following is a description of a sample design that meets the 
final survey guidelines and, based upon NHTSA's experience in 
developing and reviewing such designs, is presented as a reasonably 
accurate and practical design. Depending on the data available in a 
State, substitutions in this design can be made without loss of 
accuracy. This information is intended only as an example of a 
complying survey design and to provide guidance for States 
concerning recommended design options. These are not design 
requirements. It is recommended that State surveys of safety belt 
use be designed by qualified survey statisticians.

I. Sample Design

    A. Sample population: It is recommended that all controlled 
intersections or all roadway segments in the State (or in the parts 
of the State that have not been excluded by the 85 present 
demographic guideline) be eligible for sampling.
    B. First Stage: Usually, counties are the best candidates for 
primary sampling units (PSUs). In large States with differing 
geographic areas, it is recommended that stratification of PSUs by 
geographic region be employed prior to PSU selection. Counties 
should be randomly selected, preferably with probabilities 
proportional to vehicle miles of travel (VMT) in each county. If VMT 
is not available by county, PSUs can also be selected with 
probability proportional to county population. When sampling PSUs, 
States should ensure that an adequate mix of rural and urban areas 
are represented. In some cases, urban/rural stratification must be 
employed prior to PSU selection. In other cases, it may be more 
practical to perform urban/rural stratification at the second 
sampling stage.
    C. Second Stage: Within sampled PSUs, it is recommended that 
road segments be stratified by road type. For example, a two-strata 
design might be major roads vs. local roads, a three strata design 
might be high, medium and low traffic volume roads. The sample 
should be allocated to these strata by estimated annual VMT in each 
stratum. The sample of road segments within a stratum should be 
selected with probability proportional to average daily VMT. When 
enumerating all local roads is impractical, additional stages of 
selection can be introduced and alternative sample probabilities can 
be used. For example, census tracts within counties can be selected 
with probability proportional to VMT, or, if VMT is not available, 
proportional to the square root of the population. Next, within each 
sampled census tract, road segments can be selected.
    D. Sample Size: The following tables are provided as rough 
guidelines for determining sample size for estimating belt use with 
the required level of precision. The numbers are based on results 
from previous probability-based seat belt surveys.

                   Determining First Stage Sample Size                  
------------------------------------------------------------------------
                                                                 Number 
                                                                   of   
                  Number of counties in State                   counties
                                                                   in   
                                                                 sample 
------------------------------------------------------------------------
10............................................................         7
20............................................................        11
30............................................................        13
40............................................................        15
50............................................................        16
60............................................................        17
70............................................................        18
80............................................................        19
90............................................................        19
100-120.......................................................        20
130-170.......................................................        21
More than 180.................................................        22
------------------------------------------------------------------------


                  Determining Second Stage Sample Size                  
------------------------------------------------------------------------
                                                                 Number 
                                                                 of road
                                                                segments
    Average number of road segments in each sampled county       sampled
                                                                 in each
                                                                 sample 
                                                                 county 
------------------------------------------------------------------------
50............................................................        19
60............................................................        20
70............................................................        21
80............................................................        21
90............................................................        22
100...........................................................        23
200...........................................................        26
300...........................................................        27
400...........................................................        27
500-900.......................................................        28
More than 1000................................................        29
------------------------------------------------------------------------

    E. Example: To achieve the required level of precision, a State 
with 100 counties would sample 20 counties at the first stage. At 
the second stage, assuming an average of 100 road segments in each 
sampled county, a sample of 23 road segments per county would be 
selected. The total sample size would be 20 x 460 observational 
sites.

II. Data Collection

    A. Exact observation sites, such as the specific intersection on 
a road segment, should be determined prior to conducting the 
observations.
    B. Direction of traffic to be observed should be determined 
prior to conducting the observations.
    C. If traffic volume is too heavy to accurately record 
information, predetermined protocol should exist for selecting which 
travel lanes to observe.
    D. Observations should be conducted for a predetermined time 
period, usually one hour. Time periods should be the same at each 
site.
    E. To minimize travel time and distance required to conduct the 
observations, clustering of sampled sites can be done. Sample sites 
should be grouped into

[[Page 46394]]

geographic clusters, with each cluster containing major and local 
roads. Assignment of sites and times within clusters should be 
random.
    F. Two counts should be recorded for all eligible vehicles:
    1. Number of front seat outboard occupants.
    2. Number of these occupants wearing shoulder belts.

III. Estimation

    A. Observations at each site should be weighted by the site's 
final probability of selection.
    B. An estimate of one standard error should be calculated for 
the estimate of belt use. Using this estimate, 95 percent confidence 
intervals for the estimate of safety belt use should be calculated.

    Issued on: August 26, 1998.
Ricardo Martinez,
Administrator, National Highway Traffic Safety Administration.
[FR Doc. 98-23410 Filed 8-27-98; 11:54 am]
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