Document ID: NHTSA-2016-0052-0001
Agency: nhtsa
Document Type: Proposed Rule
Title: Federal Motor Vehicle Safety Standards: Bus Emergency Exits and Window Retention and Release, Anti-Ejection Glazing for Bus Portals
Posted Date: 2016-05-06T04:00Z

[Federal Register Volume 81, Number 88 (Friday, May 6, 2016)]
[Proposed Rules]
[Pages 27903-27932]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-10418]

[[Page 27903]]

Vol. 81

Friday,

No. 88

May 6, 2016

Part III

Department of Transportation

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National Highway Traffic Safety Administration

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49 CFR Part 571

Federal Motor Vehicle Safety Standards; Bus Emergency Exits and Window 
Retention and Release, Anti-Ejection Glazing for Bus Portals; Proposed 
Rule

  Federal Register / Vol. 81 , No. 88 / Friday, May 6, 2016 / Proposed 
Rules  

[[Page 27904]]

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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. NHTSA-2016-0052]
RIN 2127-AL36

Federal Motor Vehicle Safety Standards; Bus Emergency Exits and 
Window Retention and Release, Anti-Ejection Glazing for Bus Portals

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

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This NPRM proposes a new Federal Motor Vehicle Safety Standard 
(FMVSS) No. 217a, ``Anti-ejection glazing for bus portals,'' to drive 
the installation of advanced glazing in high-occupancy buses 
(generally, over-the-road buses (of any weight) and non-over-the-road 
buses with a gross vehicle weight rating greater than 11,793 kilograms 
(26,000 pounds). The new standard would specify impactor testing of 
glazing material. In the tests, a 26 kilogram (57 pound) impactor would 
be propelled from inside a test vehicle toward the window glazing at 
21.6 kilometers/hour (13.4 miles per hour). The impactor and impact 
speed would simulate the loading from an average size unrestrained 
adult male impacting a window on the opposite side of a large bus in a 
rollover. Performance requirements would apply to side and rear 
windows, and to glass panels and windows on the roof to mitigate 
partial and complete ejection of passengers from these windows and to 
ensure that emergency exits remain operable after a rollover crash. 
NHTSA also proposes to limit the protrusions of emergency exit latches 
into emergency exit openings of windows to ensure they do not unduly 
hinder emergency egress.
    This NPRM is among the rulemakings issued pursuant to NHTSA's 2007 
Approach to Motorcoach Safety and DOT's Departmental Motorcoach Safety 
Action Plan. In addition, to the extent warranted under the National 
Traffic and Motor Vehicle Safety Act, establishing advanced glazing 
standards for the side and rear portals of the subject buses would 
fulfill a statutory provision of the Motorcoach Enhanced Safety Act of 
2012 (incorporated and passed as part of the Moving Ahead for Progress 
in the 21st Century Act).

DATES: Comments must be received on or before July 5, 2016.

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, M-30, U.S. Department of 
Transportation, West Building, Ground Floor, Rm. W12-140, 1200 New 
Jersey Avenue SE., Washington, DC 20590.
     Hand Delivery or Courier: West Building Ground Floor, Room 
W12-140, 1200 New Jersey Avenue SE., between 9 a.m. and 5 p.m. Eastern 
Time, Monday through Friday, except Federal holidays.
     Fax: (202) 493-2251.
    Regardless of how you submit your comments, please mention the 
docket number of this document.
    You may also call the Docket at 202-366-9324.
    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.
    Privacy Act: Please see the Privacy Act heading under Rulemaking 
Analyses and Notices.

FOR FURTHER INFORMATION CONTACT:  For non-legal issues: Ms. Shashi 
Kuppa, Office of Crashworthiness Standards (telephone: 202-366-3827) 
(fax: 202-493-2990). For legal issues: Ms. Deirdre Fujita, Office of 
the Chief Counsel (telephone: 202-366-2992) (fax: 202-366-3820). The 
mailing address for these officials is: National Highway Traffic Safety 
Administration, 1200 New Jersey Avenue SE., Washington, DC 20590.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Executive Summary
II. Background
    a. NHTSA's Statutory Authority
    b. NHTSA's 2007 Approach to Motorcoach Safety
    c. DOT's 2009 Task Force Action Plan and 2012 Update
    d. NTSB Recommendations
    e. NHTSA's Previous Work on Motorcoach Crashworthiness Standards
    1. Seat Belt Final Rule
    2. Rollover Structural Integrity NPRM
III. Safety Need
    a. Overview
    b. FARS Data
IV. Research
    a. Joint NHTSA and Transport Canada Motorcoach Program (Martec 
Study)
    b. NHTSA's Motorcoach Side Glazing Research
    1. Testing on the MCI D-Series Motorcoach Section Emergency Exit 
Side Windows
    2. Testing of MCI, Prevost, and Van Hool Emergency Exit Windows 
and Latches on Test Frames
    3. Testing of MCI, Prevost, and Van Hool Emergency Exit Windows 
With Countermeasure Latches
    4. Pre-Broken Glazing Impact Tests of MCI E/J-Series Emergency 
Exit Windows With Countermeasure Latches
    5. Testing of MCI E/J-Series Fixed Windows (Martec Study 
Conditions)
    c. NHTSA's Large Bus Rollover Structural Integrity Research
    1. MY 1991 Prevost Bus
    2. MY 1992 MCI Bus
    3. MY 2000 MCI Bus
V. Overview of Proposed Requirements
VI. Test Procedure Specifications
    a. Impactor
    b. Test Speed
    c. ``Portal'' Improvements
    d. Definition of Daylight Opening
    e. Glass Breakage Procedure
VII. Performance Requirements
    a. Unbroken Glazing
    b. Broken Glazing
VIII. Other Proposed Requirements
    a. Latch Protrusions
    b. Latch Workable After Impact
IX. Applicability
X. Retrofitting
XI. Lead Time
XII. Additional MAP-21 Considerations
XIII. Overview of Benefits and Costs
XIV. Regulatory Notices and Analyses
XV. Public Participation

I. Executive Summary

    One of the factors NHTSA considers in determining the priorities of 
our rulemaking projects is to ensure the protection of passengers in 
high-occupancy vehicles. In 2007, NHTSA published a comprehensive plan 
pertaining to improvements in motorcoach safety.\1\ NHTSA developed 
this plan in response to several National Transportation Safety Board 
(NTSB) recommendations, and also to focus agency resources and research 
on improving the safety of these vehicles. NHTSA's motorcoach safety 
plan identified four specific areas where we could most effectively 
address open NTSB recommendations and most expeditiously achieve our 
goals. The four priority areas were: Requiring seat belts (minimizing 
passenger and driver ejection from the motorcoach), improved roof 
strength, emergency evacuation, and fire safety.\2\
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    \1\ Docket No. NHTSA-2007-28793, NHTSA's Approach to Motorcoach 
Safety. In NHTSA's plan, ``motorcoach'' referred to inter-city 
transport buses.
    \2\ Motorcoach safety was also the focus of a DOT-wide action 
plan. DOT issued a Departmental Motorcoach Safety Action Plan in 
2009 which addressed additional factors such as driver fatigue and 
operator maintenance schedules. An update to the 2009 plan was 
published in December 2012, see http://www.fmcsa.dot.gov/sites/fmcsa.dot.gov/files/docs/Motorcoach-Safety-Action-Plan-2012.pdf.

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[[Page 27905]]

    Work on NHTSA's safety plan is ongoing. In 2013, the agency 
published a final rule \3\ requiring seat belts for each passenger 
seating position in all new over-the-road buses (OTRBs) \4\ regardless 
of bus GVWR, and in new ``other'' buses (i.e., large buses other than 
OTRBs \5\) with GVWRs greater than 11,793 kilograms (kg) (26,000 pounds 
(lb)). In 2014, NHTSA published an NPRM proposing that these buses, and 
prison buses, meet increased structural integrity requirements to 
protect both restrained and unrestrained occupants in rollover 
crashes.\6\ NHTSA also has issued a final rule on electronic stability 
control \7\ and has completed research studies on improved motorcoach 
emergency evacuation and fire safety.\8\
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    \3\ 78 FR 70416; November 25, 2013.
    \4\ An over-the-road bus is a bus characterized by an elevated 
passenger deck located over a baggage compartment. Excluded from the 
seat belt requirement are school buses and prison buses.
    \5\ Some buses are also excluded from this latter category, such 
as transit and school buses, prison buses, and perimeter seating 
buses.
    \6\ 79 FR 46090; August 6, 2014.
    \7\ 80 FR 36050; June 23, 2015.
    \8\ For research reports on emergency evacuation, see Docket No. 
NHTSA-2007-28793-22 and -24. For fire safety, Docket No. NHTSA-2007-
28793-0027.
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    Today's NPRM complements the 2014 rollover structural integrity 
NPRM to further minimize passenger and driver ejection from 
motorcoaches and other large buses. It also enhances emergency 
evacuation from the vehicle.
    This advanced glazing NPRM also fulfills a statutory mandate on 
motorcoach safety set forth in the ``Moving Ahead for Progress in the 
21st Century Act'' (MAP-21). On July 6, 2012, President Obama signed 
MAP-21, which incorporated the ``Motorcoach Enhanced Safety Act of 
2012'' in subtitle G (sections 32701 et seq.). Among other matters, the 
Motorcoach Enhanced Safety Act requires the DOT to ``prescribe 
regulations that address the following commercial motor vehicle 
standards,'' if the Secretary determines that such standards meet the 
requirements and considerations set forth in subsections (a) and (b) of 
section 30111 of title 49, United States Code (section 32703(b)). 
Section 32703(b)(2) of MAP-21 states that the DOT ``shall consider 
requiring advanced glazing standards for each motorcoach portal and 
shall consider other portal improvements to prevent partial and 
complete ejection of motorcoach passengers, including children.'' \9\ 
Under MAP-21 (section 32702), ``advanced glazing'' means glazing 
installed in a portal on the side or the roof of a motorcoach that is 
designed to be highly resistant to partial or complete occupant 
ejection in all types of motor vehicle crashes.
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    \9\ Under MAP-21 (sec. 32702), ``motorcoach'' means an over-the-
road bus, but does not include a bus used in public transportation 
provided by, or on behalf of, a public transportation agency, or a 
school bus. ``Portal'' is also defined in sec. 32702. The 
definitions are discussed further later in this preamble.
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    This NPRM proposes new requirements, in an FMVSS No. 217a, to drive 
the installation of advanced glazing in portals \10\ of covered buses 
(buses subject to the proposed rollover structural integrity 
requirements, except for prison buses).\11\ The tests are based on 
procedures developed by NHTSA and Transport Canada to improve 
motorcoach glazing and bonding techniques to prevent ejections. 
(``Motor Coach Glazing Retention Test Development for Occupant Impact 
During a Rollover,'' Martec Technical Report #TR-06-16, Rev 4, August 
2006 (``Martec study'').) The proposed test procedures are also based 
on a follow-on NHTSA research study.\12\
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    \10\ A portal is an opening that could permit partial or 
complete ejection of an occupant from the vehicle in the event of a 
crash involving the vehicle.
    \11\ We have proposed these requirements by way of a newly 
proposed FMVSS No. 217a. If a final rule is issued, we may keep the 
requirements in Standard No. 217a or we may incorporate them into 
FMVSS No. 217.
    \12\ ``Motorcoach Side Glazing Retention Research, ``NHTSA 
Report DOT HS 811 862, http://www.nhtsa.gov/Research/ci.Defects+Analysis+and+Crashworthiness+Division.print, Last 
accessed on December 23, 2015.
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    The glazing types currently used in the motorcoach industry for 
side windows are single-pane laminated glass, single-pane tempered (or 
``toughened'') glass, or a double-pane of either laminated or tempered 
glass or a combination of both. A single-pane laminated glass actually 
contains two thin glass layers held together by an interlayer, 
typically of polyvinyl butyral (PVB). The interlayer works to keep the 
outer layers of glass bonded together in the event they break or crack, 
and prevents the formation of large shards of sharp glass. Laminated 
glass may crack or splinter upon impact with the ground, but can still 
provide a means of keeping passengers within the occupant compartment 
of the bus if the glazing is retained within the window frame, the PVB 
interlayer is not excessively torn or punctured, and the window latch 
remains closed. We believe that laminated glass could meet the 
requirements proposed in this NPRM. We consider glass meeting the 
requirements to be ``advanced glazing.''
    Tempered glass is glass processed with controlled thermal or 
chemical treatments. These treatments increase the strength of the 
glass, and also create balanced internal stresses so that when the 
glass does break, it breaks or crumbles into smaller granular chunks 
instead of large jagged shards. Tempered glass is stronger than 
laminated glass, but with tempered glass, occupant loading to the 
window during the rollover event and the bus impact with the ground can 
potentially shatter tempered glass, causing the glazing to vacate the 
window frame and create an ejection portal.
    NHTSA is proposing performance requirements that covered buses 
would have to meet by way of anti-ejection safety countermeasures to 
prevent partial and complete ejection of passengers. We would adopt a 
new FMVSS No. 217a that specifies impactor testing of glazing material. 
In the tests, a 26 kg (57 lb) impactor would be propelled from inside 
the test vehicle toward the window glazing at 21.6 kilometers per hour 
(km/h) (13.4 miles per hour (mph)). Each side and rear window and glass 
panel/window on the roof would be subject to any one of three impacts, 
as selected by NHTSA in a compliance test: (a) An impact near a 
latching mechanism of an intact window \13\; (b) an impact at the 
center of the daylight opening \14\ of an intact window; and (c) an 
impact at the center of the daylight opening of a pre-broken window. 
The impactor and impact speed in these proposed tests, developed in the 
Martec study, simulate the loading from an average size adult male 
impacting a window on the opposite side of a large bus in a rollover.
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    \13\ For non-emergency exit fixed side and rear windows and 
fixed glass panels on the roof, the proposed test would be conducted 
at the location of one of the fixed latches or discrete attachment 
points. For fully rubber bonded or glued windows with no latch 
mechanisms, the test would be conducted along the center of the 
lower window edge one inch above the daylight opening periphery.
    \14\ Center of daylight opening is the center of the total 
unobstructed window opening that would result from the removal of 
the glazing.
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    The proposed performance requirements are as follows:
     In tests described in (a) and (b) in the previous 
paragraph, the window would have to prevent passage of a 102 millimeter 
(mm) (4 inch) diameter sphere during the impact, and after the test. 
The agency would assess the window during the impact by determining 
whether any part of the window passes a reference plane defined during 
a pre-test set up procedure. These requirements would ensure that 
glazing is securely bonded to window frames, no potential ejection 
portals are created due to breaking of

[[Page 27906]]

the glass, and the windows remain closed when impacted.
     In the test of (c) above, the maximum displacement of the 
impactor at the center of daylight opening would be limited to 175 mm 
(6.9 inches) for pre-broken glazing. This requirement in particular 
would drive the installation of advanced glazing. The requirement would 
also help ensure the advanced glazing reasonably retains occupants 
within the structural sidewall of the bus even when the glass 
surrounding the PVB interlayer is broken. It also ensures that no 
potential ejection portals are created during and after impact.
     Emergency exit latch protrusions may not extend more than 
one inch into the emergency exit opening of the window when the window 
is opened to the minimum emergency egress opening (allowing passage of 
an ellipsoid 500 mm (19.7 inches) wide by 300 mm (11.8 inches) high). 
This requirement would minimize the potential for the latch plate 
protrusions (or other projections) to hinder the emergency egress of 
passengers.
     Latches would have to be functional following the impact 
test to ensure that occupants can open the emergency exits to egress 
the vehicle after the crash.
    The Motorcoach Enhanced Safety Act emphasizes anti-ejection safety 
countermeasures, particularly advanced glazing (Sec.  32703(b)(2)). 
With regard to advanced glazing standards, NHTSA's strategy has been 
first to seek improvements to the rollover structural integrity of 
motorcoaches (roof strength and crush resistance) and then to pursue 
measures that would drive use of advanced glazing. This ordered 
approach is based on findings from the Martec study that found the 
integrity of the bus structure has a profound impact on the 
effectiveness of glazing as an anti-ejection safety countermeasure. 
That is, in the absence of a threshold of requisite performance for bus 
structural integrity, a twisting motion of a bus in a rollover could 
simply pop out any advanced glazing used in the windows and negate the 
potential benefits of the glazing in mitigating occupant ejection.
    To better ensure that the full benefits of anti-ejection 
countermeasures such as advanced glazing could be realized, we adopted 
a holistic approach. We first focused on improving bus structural 
integrity and the strength of side window mountings. The 2014 NPRM on 
large bus structural integrity proposed requirements that would 
increase the likelihood that bus glazing will be retained in their 
mountings in a rollover.\15\ Next in our strategy is issuance of 
today's NPRM, which has performance requirements that would increase 
use of advanced glazing that prevent partial or complete ejection of 
motorcoach passengers and further ensure the integrity of glazing 
mounting. Today's NPRM directly addresses the directive in section 
32703(b)(2) of the Motorcoach Enhanced Safety Act that NHTSA consider 
requiring advanced glazing standards for each motorcoach portal.
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    \15\ The 2014 rollover structural integrity NPRM proposes 
performance requirements that must be met when the bus is tipped 
over from an 800 mm (31.5 inch) raised platform onto a hard level 
surface. Among other requirements, the proposed standard would 
require that the occupant ``survival space'' (space around occupant 
seating positions) be maintained during and after the dynamic test, 
and that side window glazing opposite the impacted side of the 
vehicle remain attached to its mounting such that there is no 
opening that will allow the passage of a 102 mm (4 inch) diameter 
sphere. These proposed requirements would help ensure glazing is 
retained in the windows by limiting the twisting motion of a bus and 
strengthening window mountings.
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    We have designed this NPRM in furtherance of NHTSA's goal to 
enhance the safety of all heavy buses used in intercity bus 
transportation, while attending to the Motorcoach Enhanced Safety Act's 
focus on over-the-road buses (motorcoaches). Since today's NPRM builds 
on the 2014 rollover structural integrity NPRM, we propose to apply 
today's advanced glazing proposal to the vehicles subject to the 2014 
NPRM.16 17
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    \16\ With the exception of prison buses. We have tentatively 
determined that an advanced glazing standard would not be 
appropriate for prison buses since these buses typically have bars 
over the windows.
    \17\ Note that this NPRM proposes requirements limiting how far 
emergency exit latches may protrude into the exit space. We propose 
applying the requirement to the buses to which NHTSA proposed would 
be subject to the 2014 structural integrity NPRM, except prison 
buses. We are also proposing to apply the requirement to school 
buses, and are considering applying the proposed maximum emergency 
exit latch protrusion requirements to all buses governed under FMVSS 
No. 217. Comments are requested on this issue.
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    NHTSA estimates that this rulemaking would be cost beneficial.\18\
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    \18\ NHTSA has developed a Preliminary Regulatory Evaluation 
(PRE) that discusses issues relating to the potential costs, 
benefits and other impacts of this regulatory action. The PRE is 
available in the docket for this NPRM and may be obtained by 
downloading it or by contacting the Docket at the address or 
telephone number provided at the beginning of this document.
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    The agency estimates an annual incremental material cost for all 
new buses covered by this proposed rule to be $0.19 million (see Table 
1 below). The countermeasures would likely be advanced glazing and 
improved emergency exit latches, resulting in an average incremental 
material cost per bus of $87 for buses covered under today's proposed 
rule. We estimate the testing cost of $8,700 per bus model. We estimate 
there would be no weight increase due to the proposed requirements; in 
fact, there could be a weight reduction of approximately 10.5-15 kg 
(23-33 lb) per window (125.5-180 kg (276-396 lb) per bus) as glazing 
designs change from a double-glazed tempered/tempered configuration to 
a single-glazed laminated configuration. We estimate that the proposal 
would result in fuel saving of $2.18 million to $2.9 million. This 
exceeds the material costs of $0.19 million for the proposal.
    Beyond the benefits attributable to the agency's final rules on 
seat belts and ESC and a potential final rule on rollover structural 
integrity that also may apply to the subject buses, we estimate that 
requiring new subject buses to meet the proposed performance criteria 
would save 1.54 lives and prevent 0.4 serious to critical injuries 
annually if 15 percent of occupants use seat belts, and save 0.33 lives 
and prevent 0.08 serious to critical injuries annually if 84 percent of 
occupants use seat belts. Thus, we estimate that this proposal would 
save 1.6 equivalent lives annually (undiscounted) if 15 percent of 
occupants use seat belts, and 0.34 equivalent lives annually 
(undiscounted) if 84 percent of occupants use seat belts (see Table 2, 
below).\19\
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    \19\ NHTSA used the same low seat belt usage rate estimate of 15 
percent from the November 25, 2013 final rule requiring seat belts 
on motorcoaches and other large buses (78 FR 70416). The agency also 
utilized the same source of information to establish the high seat 
belt usage rate estimate (the National Occupant Protection Use 
Survey). Today's NPRM uses the 2009 data which estimates seat belt 
use of passenger vehicles to be 84 percent. See 2009 National 
Occupant Protection Use Survey. More information at: http://www-nrd.nhtsa.dot.gov/pubs/811100.pdf.
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    Since the fuel savings from the proposed rule would be far greater 
than the material costs of this proposal, we did not estimate cost per 
equivalent lives saved. The estimated net cost/benefit impact ranges 
from a net benefit of $5.87 million to $17.52 million at the 3 percent 
discount rate and a net benefit of $4.37 million to $13.15 million at 
the 7 percent discount rate (see Table 3, below).

                     Table 1--Estimated Annual Costs
                             [2013 dollars]
------------------------------------------------------------------------
              Potential costs
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Material Costs Per Vehicle................  $87
Material Costs, Total New Fleet...........  $0.19 Million
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[[Page 27907]]

                   Table 2--Estimated Annual Benefits
                  [Undiscounted equivalent lives saved]
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------------------------------------------------------------------------
15 percent belt usage.....................................          1.6
84 percent belt usage.....................................          0.34
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                                        Table 3--Annualized Net Benefits
                                          [In millions of 2013 dollars]
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                       Discount rate                            Benefits          Net costs       Net benefits
----------------------------------------------------------------------------------------------------------------
3%........................................................      $13.22-$2.82     ($4.30-$3.05)      $17.52-$5.87
7%........................................................       $9.95-$2.12     ($3.20-$2.25)      $13.15-$4.37
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    NHTSA has considered retrofit requirements and has made the 
following tentative conclusions. The agency does not believe it would 
be sensible to apply the requirements proposed today to buses that do 
not have sufficient structural integrity to retain the advanced glazing 
in a rollover. If the advanced glazing were to pop out in a rollover, 
the benefits of the glazing would not be achieved. Yet, Congress was 
particularly interested in a possible retrofit requirement for advanced 
glazing. Section 32703(e)(2)(A) of MAP-21 states that the Secretary may 
assess the feasibility, benefits, and costs with respect to the 
application of any requirement established under section 32703(b)(2), 
regarding advanced glazing, to motorcoaches manufactured before the 
date on which the requirement applies to new motorcoaches. Thus, NHTSA 
is requesting comments on the feasibility, benefits, and costs of any 
potential requirement to retrofit existing buses with advanced glazing.

II. Background

a. NHTSA's Statutory Authority

    NHTSA is proposing today's NPRM pursuant to and in accordance with 
its authority under the National Traffic and Motor Vehicle Safety Act 
and the relevant provisions of MAP-21.
National Traffic and Motor Vehicle Safety Act (Vehicle Safety Act)
    Under 49 United States Code (U.S.C.) Chapter 301, Motor Vehicle 
Safety (49 U.S.C. 30101 et seq.), the Secretary of Transportation is 
responsible for prescribing motor vehicle safety standards that are 
practicable, meet the need for motor vehicle safety, and are stated in 
objective terms (section 30111(a)). ``Motor vehicle safety'' is defined 
in the Vehicle Safety Act (section 30102(a)(8)) as ``the performance of 
a motor vehicle or motor vehicle equipment in a way that protects the 
public against unreasonable risk of accidents occurring because of the 
design, construction, or performance of a motor vehicle, and against 
unreasonable risk of death or injury in an accident, and includes 
nonoperational safety of a motor vehicle.'' ``Motor vehicle safety 
standard'' means a minimum standard for motor vehicles or motor vehicle 
equipment performance (section 30102(a)(9)). When prescribing such 
standards, the Secretary must consider all relevant available motor 
vehicle safety information (section 30111(b)(1)). The Secretary must 
also consider whether a proposed standard is reasonable, practicable, 
and appropriate for the particular type of motor vehicle or motor 
vehicle equipment for which it is prescribed (section 30111(b)(3)) and 
the extent to which the standard will further the statutory purpose of 
reducing traffic accidents and associated deaths and injuries (section 
30111(b)(4)). The responsibility for promulgation of FMVSSs is 
delegated to NHTSA (49 CFR 1.95).
MAP-21 (Incorporating the Motorcoach Enhanced Safety Act of 2012)
    On July 6, 2012, President Obama signed MAP-21, which incorporated 
the ``Motorcoach Enhanced Safety Act of 2012'' into subtitle G. Section 
32703(b) of MAP-21 requires the Secretary to prescribe regulations that 
would address certain aspects of motorcoach crash performance within 
two years if the Secretary determines that the standards would meet the 
requirements and considerations of subsections (a) and (b) of section 
30111 of the Vehicle Safety Act.
    Section 32703(b)(2) of MAP-21 directs the Secretary to consider 
requiring advanced glazing standards for each motorcoach portal and to 
consider other portal improvements to prevent partial and complete 
ejection of motorcoach passengers, including children. Under section 
32702, ``portal'' means any opening on the front, side, rear, or roof 
of a motorcoach that could, in the event of a crash involving the 
motorcoach, permit the partial or complete ejection of any occupant 
from the motorcoach, including a young child. Section 32703(b)(2) also 
states that in prescribing such standards, the Secretary shall consider 
the impact of such standards on the use of motorcoach portals as a 
means of emergency egress.
    MAP-21 contains various other provisions that are relevant to this 
rulemaking. Section 32702 states that ``motorcoach'' has the meaning 
given to the term ``over-the-road bus'' in section 3038(a)(3) of the 
Transportation Equity Act for the 21st Century (TEA-21).\20\ Section 
32702 of MAP-21 excludes transit buses and school buses from the 
``motorcoach'' definition.
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    \20\ Section 3038(a)(3) of TEA-21 (see 49 U.S.C. 5310 note) 
defines ``over-the-road bus'' as ``a bus characterized by an 
elevated passenger deck located over a baggage compartment.''
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    MAP-21 sets forth compliance dates. It directs the Secretary to 
apply any regulation prescribed in accordance with section 32703(b) 
(and several other subsections) to all motorcoaches manufactured more 
than 3 years after the date on which the regulation is published 
(section 32703(e)(1)). In addition, the Secretary may assess the 
feasibility, benefits, and costs of applying any requirement 
established under section 32703(b)(2) to ``motorcoaches manufactured 
before the date on which the requirement applies to new motorcoaches'' 
(retrofit) (section 32703(e)(2)).
    Finally, MAP-21 also authorizes the Secretary to combine the 
required rulemaking actions as the Secretary deems appropriate (section 
32706(b)).

b. NHTSA's 2007 Approach to Motorcoach Safety

    In 2007, NHTSA undertook a comprehensive review of motorcoach 
safety issues and the course of action that the agency could pursue to 
address

[[Page 27908]]

them. The agency considered various prevention, mitigation, and 
evacuation approaches in developing the course of action. Many 
considerations were factored into determining the priorities, 
including: Cost and duration of testing, development, and analysis 
required; likelihood that the effort would lead to the desired and 
successful conclusion; target population and possible benefits that 
might be realized; and anticipated cost of implementing the ensuing 
requirements into the motorcoach fleet.
    The result was NHTSA's 2007 plan, ``NHTSA's Approach to Motorcoach 
Safety,'' \21\ in which we identified the following areas as the 
highest priorities for possible near term regulatory action to enhance 
motorcoach safety: (1) Seat belts; (2) improved roof strength; (3) 
emergency evacuation; and (4) fire safety. For addressing passenger 
ejection (action (1) above), we first pursued the incorporation of 
passenger seat belts as the most expeditious way to mitigate ejection. 
The agency's seat belt rulemaking, discussed further in subsection (e) 
below, began NHTSA's implementation of our Motorcoach Safety Plan. 
Today's NPRM further advances the implementation of the plan.
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    \21\ Docket No. NHTSA-2007-28793-001.
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c. DOT's 2009 Task Force Action Plan and 2012 Update

    In 2009, DOT issued a Departmental ``Motorcoach Safety Action 
Plan,'' which outlined a Department-wide strategy to enhance motorcoach 
safety.\22\ An update of the plan was issued in December 2012.\23\ In 
addition to the four priority action items specified in NHTSA's 2007 
plan, the DOT plan discussed additional factors for enhancing 
motorcoach safety, such as electronic stability control systems, event 
data recorders, and driver fatigue and operator maintenance issues. 
Departmental agencies continue to work on the motorcoach safety 
initiatives related to their administrations.
---------------------------------------------------------------------------

    \22\ https://www.fmcsa.dot.gov/sites/fmcsa.dot.gov/files/docs/MotorcoachSafetyActionPlan_final2009report-508.pdf.
    \23\ http://www.fmcsa.dot.gov/safety/passenger-safety/motorcoach-safety-action-plan-2012.
---------------------------------------------------------------------------

d. NTSB Recommendations

    This NPRM addresses the following NTSB recommendations pertaining 
to window glazing and emergency exits.
H-99-049
    NTSB initiated a special investigation reviewing 36 motorcoach 
crashes that were investigated from 1968 through 1997.\24\ It found 
that of the 168 occupant fatalities, 106 occurred in crashes involving 
a rollover. Of those 106 fatalities, 64 were ejected from the bus.
---------------------------------------------------------------------------

    \24\ NTSB/SIR-99/04 PB98-917006; Highway Special Investigation 
Report: Bus Crashworthiness Issues; September, 1999.
---------------------------------------------------------------------------

    NTSB also found that glazing composition may mitigate injury during 
a rollover event. In one investigation of a 1988 crash,\25\ a 1987 
Motor Coach Industries, Inc., intercity-type coach overturned on its 
right side and slid 220 feet across the highway before coming to rest. 
There was no intrusion into the occupant compartment and no fatalities. 
Forty-nine passengers and the driver sustained minor to severe injuries 
such as fractured ribs, lacerations, abrasions, and contusions. The 27 
passengers on the left side were thrown from their seats and fell on 
top of the 22 right side passengers during the overturn sequence; 
however, all of the passengers were contained within the coach through 
the event. NTSB determined that because the bus's abrasive-resistant, 
coated acrylic windows did not break, the passengers may have been 
afforded protection from contacting the road surface and possibly 
sustaining more serious or even fatal injuries. NTSB concluded that 
buses equipped with advanced glazing may decrease the number of 
ejections of unrestrained passengers and reduce the risk of serious 
injury to restrained passengers during bus crashes, particularly 
rollover events. NTSB issued the following recommendation to NHTSA:
---------------------------------------------------------------------------

    \25\ NTSB/HAR-89/01/SUM PB89-916201; Highway Accident Summary 
Report: Intercity-Type Buses Chartered for Service to Atlantic City; 
April 1989.
---------------------------------------------------------------------------

    ``H-99-049: Expand your research on current advanced glazing to 
include its applicability to motorcoach occupant ejection prevention, 
and revise window glazing requirements for newly manufactured 
motorcoaches based on the results of this research.''
H-11-037
    On August 5, 2010, a multi-vehicle accident occurred in Gray 
Summit, Missouri, involving a 2007 Volvo tractor, a 2007 GMC Sierra 
extended cab pickup truck, a 2003 Blue Bird 71-passenger bus (``lead 
school bus''), and a 2001 Blue Bird 72-passenger bus (``following 
school bus''). This multi-vehicle crash was investigated by NTSB in 
2011.\26\ In the collision, the lead school bus sustained moderate 
front-end damage from colliding into the back of the Sierra pickup and 
the rear of the Volvo tractor. Additionally, the rear of the lead 
school bus was severely damaged as a result of being impacted and 
overridden by the following school bus.
---------------------------------------------------------------------------

    \26\ NTSB/HAR-11/03 PB2011-916203; Multivehicle Collision 
Interstate 44 Eastbound Gray Summit, Missouri, August 5, 2010; 
December 2011.
---------------------------------------------------------------------------

    The only emergency exits available for egress on the lead school 
bus were the rear two emergency exit windows. All but one of the 
occupants in the lead bus exited the bus through the left rear 
emergency exit window. The remaining entrapped passenger was extricated 
by emergency responders and placed on a backboard before being removed 
through the right rear emergency exit window.
    Several passengers in the lead school bus, and a witness who 
assisted in the evacuation, stated in post-crash interviews that 
emergency egress was hindered by the design of the emergency exit 
window. Particularly, the 4 inch by 3 inch emergency release latch 
plate for the emergency exit window was elevated about 1 inch from the 
window base and snagged the clothing of several passengers as they were 
exiting through the window opening. In addition, because of the failure 
of the emergency exit window to independently remain in the open 
position, one individual had to hold the hinged emergency exit window 
open so that other individuals could exit the bus unimpeded.
    NTSB made three safety recommendations, including the following:
    ``H-11-037: Modify Federal Motor Vehicle Safety Standard 217 or the 
corresponding laboratory test procedure to eliminate the potential for 
objects such as latch plates to protrude into the emergency exit window 
space even when that protrusion still allows the exit window to meet 
the opening size requirements.''

e. NHTSA's Previous Work on Motorcoach Crashworthiness Standards

1. Seat Belt Final Rule
    Section 32703(a) of MAP-21 directs the Secretary to require seat 
belts for each designated seating position in motorcoaches. NHTSA 
fulfilled this mandate in 2013, issuing a final rule amending FMVSS No. 
208, ``Occupant crash protection'' to require lap/shoulder seat belts 
for each passenger seating position in: (a) All new OTRBs (except 
school buses and prison buses); and (b) in new buses other than 
OTRBs,\27\ with a GVWR greater than 11,793 kg (26,000 lb).\28\ The 
final rule significantly reduces the risk of fatality and serious 
injury in frontal crashes and

[[Page 27909]]

the risk of occupant ejection in rollovers, thus considerably enhancing 
the safety of these vehicles.
---------------------------------------------------------------------------

    \27\ Except school buses, transit buses, perimeter seating 
buses, and prison buses.
    \28\ 78 FR 70416; November 25, 2013.
---------------------------------------------------------------------------

2. Rollover Structural Integrity NPRM
    Section 32703(b)(1) of MAP-21 specifies that the Secretary is to 
establish improved roof and roof support standards that ``substantially 
improve the resistance of motorcoach roofs to deformation and intrusion 
to prevent serious occupant injury in rollover crashes involving 
motorcoaches'' if such standards meet the requirements and 
considerations of subsections (a) and (b) of section 30111 of the 
Vehicle Safety Act. In 2014, NHTSA published an NPRM proposing that 
OTRBs (except school buses) and buses other than OTRBs \29\ with a GVWR 
greater than 11,793 kg (26,000 lb) meet increased structural integrity 
requirements to protect both restrained and unrestrained occupants in 
rollover crashes. The NPRM was based on a rollover test set forth in 
the Economic Commission for Europe (ECE) Regulation No. 66, ``Uniform 
Technical Prescriptions Concerning the Approval of Large Passenger 
Vehicles with Regard to the Strength of their Superstructure,'' (ECE 
R.66).\30\
---------------------------------------------------------------------------

    \29\ Exceptions are transit buses, and perimeter seating buses.
    \30\ Supra. 79 FR 46090; August 6, 2014.
---------------------------------------------------------------------------

    NHTSA proposed performance requirements that each bus must meet 
when subjected to a dynamic rollover test. The bus is placed on a 
tilting platform that is 800 mm above a smooth and level concrete 
surface. One side of the platform is raised at a steady rate until the 
vehicle becomes unstable, rolls off the platform, and impacts the 
concrete surface below.
    The proposed rollover structural integrity test is illustrated 
below in Figure 1.
[GRAPHIC] [TIFF OMITTED] TP06MY16.037

    The following are the main proposed performance requirements that 
buses would have to meet when subjected to the rollover structural 
integrity test:
    (1) Intrusion into the ``occupant survival space,'' demarcated in 
the vehicle interior, by any part of the vehicle outside the survival 
space is prohibited;
    (2) each anchorage of the seats and overhead luggage racks must not 
completely separate from its mounting structure;
    (3) emergency exits must remain shut during the test and must be 
operable in the manner required under FMVSS No. 217 after the test; 
and,
    (4) each side window glazing opposite the impacted side of the 
vehicle must remain attached to its mounting such that there is no 
opening that will allow the passage of a 102 mm (4 inch) diameter 
sphere.

[[Page 27910]]

III. Safety Need

a. Background

    Each year, the commercial bus industry transports millions of 
people between and in cities, for long and short distance tours, school 
field trips, commuting, and entertainment-related trips. According to a 
census published by the American Bus Association (ABA) in 2008, there 
were approximately 3,400 motorcoach \31\ carriers in the United States 
and Canada in 2007.\32\ These motorcoach carriers operated over 33,000 
motorcoaches, logged nearly 750 million passenger trips, and traveled 
over 1.8 billion miles yearly. Approximately 3,100 of the carriers were 
chartered U.S. carriers that operated about 29,000 motorcoaches.
---------------------------------------------------------------------------

    \31\ As used in the ABA census report, ``motorcoach'' refers to 
an OTRB. When we discuss this report and use the term motorcoach, we 
mean an OTRB.
    \32\ ``Motorcoach Census 2008, A Benchmarking Study of the Size 
and Activity of the Motorcoach Industry in the United States and 
Canada in 2007,'' Paul Bourquin, December 18, 2008.
---------------------------------------------------------------------------

    In an updated 2011 motorcoach census,\33\ the motorcoach industry 
had grown to 4,478 carriers and 42,960 motorcoaches in the United 
States and Canada by the year 2010. In the U.S. alone, 4,088 carriers 
operated 39,324 motorcoaches. Although the number of motorcoaches on 
the road increased from 2007, the actual number of passenger trips 
logged dropped to 694 million trips, while the amount of vehicle miles 
traveled increased to 2.4 billion miles and passenger miles traveled 
increased to over 76.1 billion. In essence, the data indicated that the 
frequency of passenger trips may have decreased from 2007 to 2010, but 
the length or distance of each trip increased.
---------------------------------------------------------------------------

    \33\ ``Motorcoach Census 2011, A Benchmarking of the Study of 
the Size and Activity of the Motorcoach Industry in the Unites 
States and Canada in 2010,'' John Dunham & Associates, June 18, 
2012.
---------------------------------------------------------------------------

    Carriers with a small fleet size (less than 10 motorcoaches) have 
older average motorcoach fleet age than carriers with a large fleet 
size (more than 50 motorcoaches). In 2007, the small carriers had an 
average motorcoach fleet age of 9 years, whereas the large carriers had 
an average fleet age of 6 years. In 2010, the small carrier's average 
fleet age increased to 10 years, whereas the large carrier's average 
fleet age remained the same at 6 years old.

b. FARS Data

    NHTSA's Fatality Analysis Reporting System (FARS) \34\ was analyzed 
for a 10 year period from 2004 to 2013 to look at fatal bus crashes 
within the United States.\35\ During this period there were 85 fatal 
crashes involving all OTRBs regardless of GVWR and other covered non-
OTRBs with a GVWR >11,793 kg (26,000 lb) resulting in a total of 212 
occupant fatalities (an average of 21.2 total occupant fatalities per 
year). Tables 4 and 5 show the breakdown of the number of crashes and 
fatalities by bus body type, GVWR, and crash type, respectively.\36\ 
Fatalities resulting from other events such as fires or occupants 
jumping from a bus were not included.
---------------------------------------------------------------------------

    \34\ NHTSA's FARS contains data on a census of fatal traffic 
crashes in the United States and Puerto Rico. Crashes in FARS 
involve a motor vehicle traveling on a road customarily open to the 
public resulting in a fatality within 30 days of the crash.
    \35\ Over-the-Road Bus (Motorcoach) in the FARS database is 
identified by the bus body type category, ``cross-country/intercity 
bus,'' and large bus is identified by the bus body categories: 
``other bus,'' ``unknown bus,'' and ``van-based bus,'' and by the 
vehicle's GVWR greater than 11,793 kg (26,000 lb).
    \36\ The other two bus body types in the FARS database, transit 
bus and school bus, were also examined and the safety problem due to 
ejections in rollover accidents was found to be significantly lower 
than that in OTRBs and large buses. For the 10-year period from 2004 
to 2013, 6 passengers (or 0.81 passengers annually on average) were 
ejected in rollover crashes of school buses and transit buses with 
GVWR >11,793 kg (26,000 lb), but the ejection path was not known.
---------------------------------------------------------------------------

    There were 59 OTRB and 26 large bus crashes. Among these 85 OTRB 
and large bus crashes, 40 were rollovers, 41 were frontal crashes, and 
4 were side crashes. About 70 percent of the fatal bus crashes involved 
OTRBs among which 90 percent had a GVWR greater than 11,793 kg (26,000 
lb).

                             Table 4--Over-the-Road Bus and Large Bus Fatal Crashes
                                                (FARS 2004-2013)
----------------------------------------------------------------------------------------------------------------
                                     Rollover          Front           Side            Rear            Total
----------------------------------------------------------------------------------------------------------------
Over-the-road bus...............              33              25               1               0              59
Large bus GVWR >11,793 kg                      7              16               3               0              26
 (26,000 lb)....................
                                 -------------------------------------------------------------------------------
    Total.......................              40              41               4               0              85
----------------------------------------------------------------------------------------------------------------

                                      Table 5--Over-the Road Bus and Other Large Bus Occupant Fatalities in Crashes
                                                                    (FARS 2004-2013)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                Body type                        Over-the-road bus           Large bus GVWR >11,793 kg                         Total
-------------------------------------------------------------------------           (26,000 lb)          -----------------------------------------------
                                                                         --------------------------------
               Crash type                     Driver         Passenger        Driver         Passenger        Driver         Passenger          All
--------------------------------------------------------------------------------------------------------------------------------------------------------
Rollover................................               6             133               1               7               7             140             147
Front...................................              19              19               8              11              27              30              57
Side....................................               1               1               0               6               1               7               8
Rear....................................               0               0               0               0               0               0               0
                                         ---------------------------------------------------------------------------------------------------------------
    Total...............................              26             153               9              24              35             177             212
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The OTRB and large bus fatalities were broken down by separating 
the fatalities for drivers and passengers (Table 5). Passenger 
fatalities were significantly higher than driver fatalities, accounting 
for over 83 percent of the total fatalities, and were particularly 
prevalent in the OTRB category. Rollover events accounted for 79 
percent of OTRB and large bus passenger fatalities (compared to 21 
percent for driver fatalities).
    With the focus on passenger fatalities only, the passenger 
fatalities were further broken down based on ejection

[[Page 27911]]

status (Table 6). Of the 79 percent of OTRB and large bus passenger 
fatalities that were from rollover events, 57 percent of those 
passenger fatalities were ejected. One in eight of the passenger 
ejections had a documented known ejection portal through the side 
window of the bus. Rollovers remain the largest cause of passenger 
fatalities, for both ejected and non-ejected, in OTRB and large bus 
crashes.

                                  Table 6--OTRB and Large Bus Passenger Fatalities by Ejection Status (FARS 2004-2013)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                       OTRB                  Large bus GVWR >26,000 lb                 Total
                       Crash type                        -----------------------------------------------------------------------------------------------
                                                               Eject         No Eject          Eject         No Eject          Eject         No Eject
--------------------------------------------------------------------------------------------------------------------------------------------------------
Rollover................................................              74              59               6               1              80              60
Front...................................................               5              14               2               9               7              23
Side....................................................               1               0               0               6               1               6
Rear....................................................               0               0               0               0               0               0
                                                         -----------------------------------------------------------------------------------------------
    Total...............................................              80              73               8              16              88              89
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The agency is proposing the requirements in today's NPRM to improve 
rollover safety in high-capacity buses. The aforementioned data show 
that crashes involving rollovers and ejections present the greatest 
risk of death to the occupants of these buses. The majority of 
fatalities occur in rollovers, and nearly 60 percent of rollover 
passenger fatalities are associated with occupant ejection.
    In nearly all the recent OTRB and large bus fatal rollover events, 
there was a significant amount of structural damage to the roof and 
side structure of the vehicles, as well as open window portals. Hence, 
NHTSA tentatively believes that the prevention of occupant ejection 
through portals is a critical part of mitigating the OTRB and large bus 
fatality and injury rate.

IV. Research

    The test procedure and test device proposed in this NPRM were 
developed from the findings of several NHTSA research programs 
described in this section.

a. Joint NHTSA and Transport Canada Motorcoach Program (Martec Study)

    In 2003, NHTSA and Transport Canada entered into a joint program 
that focused on improving glazing and window retention on OTRBs to 
prevent occupant ejection. (``Motor Coach Glazing Retention Test 
Development for Occupant Impact During a Rollover,'' August 2006.) \37\ 
Using a combination of crash investigations and numerical simulations, 
the study provided the important first steps necessary to develop a 
test procedure that realistically represented the impact loads from an 
unrestrained occupant on motorcoach glazing during a rollover event. 
The program also established the basis of a dynamic test device that 
could be used to test glazing materials and bonding techniques to 
evaluate their effectiveness in preventing ejections.
---------------------------------------------------------------------------

    \37\ Motor Coach Glazing Retention Test Development for Occupant 
Impact During a Rollover, Final Report published on August 2006, 
Docket No. NHTSA-2002-11876-15.
---------------------------------------------------------------------------

    In the Martec study, the event chosen for simulation was a 
motorcoach rollover with a yaw speed of 30 km/h (18.6 mph) onto a flat 
surface, with an unrestrained occupant seated on the far side of the 
roll. Through these simulations, the Martec study determined that the 
impact velocity of an occupant striking the glazing was as much as 6.0 
meters/second (m/s) (21.6 km/h or 13.4 mph). The analysis used a 50th 
percentile adult male side impact test dummy (US-SID) numerical model 
to determine peak loading and duration. The Martec simulations 
(involving a bus rolling over on its side) showed the impact area 
between the bus occupant and window glazing was primarily along the 
side of the dummy and that the largest load on the glazing was due to 
the torso impact. It was this impact that was used as the target load 
or load profile in the dynamic impact test device development.
    The impact test device consisted of a guided piston secured to a 
platform structure along with an accumulator tank used for powering the 
guided piston (Figure 2). The mass of the impactor was 26 kg (57 lb), 
representing the effective mass measurements from the numerical 
analysis. A spring with the appropriate stiffness (258 N/m) was used to 
replicate compression of the thorax and a shoulder foam part from the 
SID was affixed to the impactor face to replicate the compression of 
the dummy's shoulder and the contact area between the dummy's shoulder 
and the glazing during impact (Figure 3).

[[Page 27912]]

[GRAPHIC] [TIFF OMITTED] TP06MY16.038

[GRAPHIC] [TIFF OMITTED] TP06MY16.039

    In the Martec study, only limited testing was performed in a test 
fixture representing an OTRB side window structure. Only one glazing 
composition was tested. No testing was done to establish the motorcoach 
fleet performance. The study recommended that further testing be 
performed using other configurations (different glazing types such as 
laminated glass and polycarbonates and mechanical latching methods) 
common in the bus industry. The study concluded that more research was 
needed to establish baseline motorcoach fleet performance, determine 
the effect of motorcoach structural integrity on window retention and 
emergency egress, and identify potential improvements for window 
retention purposes.

[[Page 27913]]

    NHTSA's follow-on test program, discussed below, was conducted to 
obtain data in these areas.

b. NHTSA's Motorcoach Side Glazing Research

    In 2011 and 2013, respectively, we completed a follow-on test 
program to the Martec study and a comprehensive test program of bus 
models and glazing designs to establish anti-ejection countermeasures 
and performance requirements.\38\ The test programs, conducted at 
NHTSA's Vehicle Research and Test Center (VRTC), investigated the 
performance of bus glazing under passenger loading (simulating a far 
side passenger impacting the roll side glazing during a quarter turn 
rollover), using standard OTRB side windows (emergency exits and fixed 
windows) and different variations of glazing and bonding techniques. 
The objectives were: (1) To evaluate the test procedure from the Martec 
study; (2) evaluate various types of motorcoach glazing material and 
bonding techniques; (3) explore countermeasures for current window 
latches that open during such impacts; and, (4) further develop test 
procedures to assess the occupant retention provided by different 
glazing materials used in bus exits and windows.
---------------------------------------------------------------------------

    \38\ Duffy, S., Prasad, A., ``Motorcoach Side Glazing Retention 
Research,'' NHTSA Technical Report DOT HS 811 862, November 2013, 
http://www.nhtsa.gov/Research/Defects+Analysis+and+Crashworthiness+Division.
---------------------------------------------------------------------------

    The following is a summary of the different testing conducted and 
the test results relevant to this NPRM. Details of the testing and the 
results can be found in Duffy et al., ``Motorcoach Side Glazing 
Retention Research,'' supra.
1. Testing on the MCI D-Series Motorcoach Section Emergency Exit Side 
Windows
    In the first stage of testing, VRTC used a section of a Motor Coach 
Industries (MCI) 1993 102D model motorcoach to conduct impact tests at 
the center of the window and near the latch. Different types of glazing 
material (laminated, tempered), double and single pane glazing, and 
different types of bonding of the glazing to the window frame were 
evaluated. The windows of the MCI 102D model were 1.5 m (59 inches) in 
length and 1 m (39.4 inches) in height and weighed between 25-29 kg 
(55-64 lb) for single glazed panes and 42-47 kg (92.5-103.5 lb) for 
double glazed panes.
    The center of daylight opening impacts were conducted using the 
Martec Study Conditions (26 kg (57 lb) impactor at an impact velocity 
of 21.6 km/h (13.4 mph)). The near latch impacts were conducted using 
the 26 kg (57 lb) impactor at impact velocities ranging from 10.3 km/h 
(6.4 mph) to 21.6 km/h (13.4 mph). Near latch impacts were also 
conducted with twist introduced on the bus frame during the impact to 
evaluate the effect of torsion of the bus frame on latch opening.\39\ 
The impact conditions in the tests with twist introduced were in 
similar conditions as those without twist.
---------------------------------------------------------------------------

    \39\ The amount of torsion introduced on the bus section frame 
was based on the torsion achieved by lifting the left front tire of 
a full-sized MCI D-series bus by approximately 1 meter (39 inches) 
using a hydraulic wheel lift which resulted in an angle of 4 degrees 
about the vehicle's longitudinal axis. Torsion was introduced to the 
bus section by applying a 18.9 kilonewton (kN) (4,250 lb) downward 
force to one entire end of the bus section and applying a 18.9 kN 
(4,250 lb) upward force to one corner of the opposite end of the bus 
section.
---------------------------------------------------------------------------

    The results of this first stage of testing are as follows:
    Center of Daylight Opening Impacts on Emergency Exit Windows of the 
MCI Bus Section:
     No windows tested opened in the center of daylight opening 
impacts under the Martec study conditions.
     Windows with tempered glass produced higher forces and 
lower displacement, than those with laminated glass.
     No windows with tempered glass broke in the center of 
daylight opening impacts. Single glazed laminated glass broke in the 
center of daylight opening impacts but the PVB layer did not tear.
     Polycarbonate windows produced lower resistance forces and 
higher displacement compared to laminated glass windows.
     Acrylic windows produced lower resistance forces compared 
to most other glazing compositions tested.
     Windows with greater PVB thickness produced reduced 
displacements.
    Near-Latch Impacts on Emergency Exit Windows of the MCI Bus 
Section:
     Under the Martec Study Conditions (26 kg (57 lb) impactor 
and 21.6 km/h (13.4 mph) impact speed), the latches released and the 
windows opened, regardless of the type of glazing material. The glazing 
material was not damaged in these impacts.
     At impact speeds (10.3 km/h (6.4 mph) to 15.8 km/h (9.8 
mph)) that are lower than the Martec Study Conditions the latches near 
the impact opened, but the window did not open because the far side 
latch remained closed.
     Paired impact tests using the 26 kg (57 lb) impactor at 
speeds of 13.9 to 15.5 km/h (8.6 to 9.6 mph) with and without torsion 
of the bus frame, showed that torsion in the bus frame either had no 
effect on latch opening or made latch opening less likely. In 6 out of 
11 pairs of comparison tests, the presence of torsion on the bus 
section did not affect whether the struck latch unlatched. In the 5 
other tests, the presence of torsion made it harder to open the latch.
2. Testing of MCI, Prevost, and Van Hool Emergency Exit Windows and 
Latches on Test Frames
    Next, VRTC expanded testing to windows of other coach series and 
those made by other manufacturers to establish fleet baseline 
performance. Market share analysis indicated that the fleet would be 
well represented by expanding the testing to an MCI E/J-series, a 
Prevost model H3-45, and a Van Hool model C2045. Van Hool and Prevost 
windows were double glazed tempered glass panes while the MCI E/J-
Series windows were either single glazed laminate glass panes or double 
glazed glass panes with tempered glazing on the exterior and laminate 
glazing on the interior. The MCI E/J-Series and the Van Hool C2045 
windows were 1.74 m (68.5 inches) in length and 1.1 m (43.3 inches) in 
height and the Prevost H3-45 model was 1.7 m (66.9 inches) in length 
and 1.2 m (47.2 inches) in height.\40\ The glazing was mounted on test 
frames that represented the side passenger window frames for each of 
the three manufacturers. The mounting methods were in accordance with 
the manufacturers' instructions. Impact tests (impacts at the center of 
daylight opening and impacts near latches) were conducted under the 
Martec Study Conditions (26 kg (57 lb) impactor with 21.6 km/h (13.4 
mph) impact speed). The significantly different latching mechanisms in 
the emergency exit windows of these three vehicle models allowed for an 
evaluation of the different types of latches.\41\ Near latch impact 
tests with the 26 kg (57 lb) impactor were also conducted at different 
impact velocities to determine the threshold velocity for latch opening 
of the different types of windows and latching mechanisms. The results 
of this phase of testing are as follows:
---------------------------------------------------------------------------

    \40\ The weight of the MCI E/J single glazed laminated window 
was 35 kg (77 lb) while that of the double glazed window was 51 kg 
(112.lb). The weight of the Prevost H3-45 was 50 kg (110 lb) and 
that of the Van Hool C2045 was 45 kg (99 lb).
    \41\ Details of the testing and the details of the windows and 
latching mechanisms in these three bus models are available in the 
NHTSA Technical Report DOT HS 811 862, November 2013.
---------------------------------------------------------------------------

    Near-Latch Impacts on Production Emergency Exit Windows:

[[Page 27914]]

     Windows from all three manufacturers exhibited latch 
openings under the Martec Study Conditions.
     The threshold impact velocity for latch opening was higher 
for the MCI E/J-Series windows than the Van Hool and Prevost windows.
    --Van Hool exhibited latch openings in the 9 to 10 km/h (5.6 to 6.2 
mph) range.
    --Prevost exhibited latch openings in the 11 to 12 km/h (6.9 to 7.5 
mph) range.
    --MCI E/J-series exhibited latch opening in the 18 to 21 km/h (11.2 
to 13.1 mph) range.
    Impacts at the Center of the Daylight Opening on Production 
Emergency Exit Windows (Martec Study Conditions):
     The MCI E/J-Series single laminate glazing window latches 
(primary and secondary) remained closed and the windows did not open.
     The Van Hool latches opened and produced window openings. 
The tempered glass panes remained intact.
     The Prevost latches opened and produced window openings. 
The tempered glass panes remained intact.
3. Testing of MCI, Prevost, and Van Hool Emergency Exit Windows With 
Countermeasure Latches
    Since latches opened in all the near latch impacts on production 
windows and in two of the three center of daylight opening impacts of 
production windows in the phase 2 tests presented above, VRTC attempted 
to modify the latch systems using simple designs to see if the windows 
would remain closed during impact under the Martec Study Conditions.
    The latching mechanism of the MCI E/J-Series production windows 
includes a lever that latches around a striker post that is press fit 
into a latch plate. Unlatching occurred in near-latch impacts by one of 
two modes: 1. The striker plate deformed and the striker post rotated 
in the direction of impact allowing the lever to slide over the striker 
post, and 2. the latch bar rotated upward during impact which opened 
the detent lever.\42\ Modifications to the MCI E/J-series latches 
involved the simplest modification to improve its performance such that 
the latch and glass remained intact. No simple countermeasures were 
identified by VRTC for the Van Hool and Prevost latches.
---------------------------------------------------------------------------

    \42\ Latching mechanisms for Prevost and Van Hool windows and 
the failures modes observed during testing are provided in detail in 
the NHTSA Technical Report DOT HS 811 862, November 2013.
---------------------------------------------------------------------------

    Center of daylight opening and near latch impacts under the Martec 
Study Conditions were conducted on the production windows with the 
countermeasure latches on the test frame. The results of this phase of 
testing are as follows:
    Near-Latch Impacts (Martec Study Conditions) on Production 
Emergency Exit Windows With Countermeasure Latches:
     The MCI I/J-series countermeasure latch and glass remained 
intact in the near-latch impacts under the Martec Study Conditions.
     The Van Hool primary countermeasure latch opened, but the 
secondary latch did not under the near-latch Martec Study Conditions. 
Only a partial window opening occurred, as the tempered glass remained 
intact.
     The Prevost countermeasure latches opened in near-latch 
impacts under the Martec Study Conditions and the window opened.
    Center of Daylight Opening Tests on Emergency Exit Windows With 
Countermeasure Latches (Martec Study Conditions):
     MCI E/J-series latches remained intact. The laminated 
inside pane broke.
     Van Hool latches remained intact. The tempered glass panes 
shattered.
     Prevost latches remained intact. The window bowed outward 
during the impact, but the tempered glass panes did not break.
4. Pre-Broken Glazing Impact Tests of MCI E/J-Series Emergency Exit 
Windows With Countermeasure Latches
    As part of the test program, VRTC conducted impact tests under the 
Martec Study Conditions on pre-broken glazing to assess glazing 
strength in the event the window is broken in a rollover prior to 
occupant loading. The objective of these tests was to develop an 
objective test procedure for pre-breaking the glazing before the impact 
tests. Various methods of pre-breaking the glazing were evaluated. 
These methods included pummeling the glazing with a hammer and punching 
holes in the glazing in specific grid patterns using an unloaded 
electric staple gun. The hole punch patterns evaluated were a 75 mm (3 
inch) diagonally offset pattern, a 50 mm (2 inch) diagonally offset 
pattern, and a 75 mm (3 inch) horizontally offset pattern. The MCI E/J-
Series was chosen to conduct pre-broken glazing impacts since the MCI 
E/J-Series model included laminated glazing that would still offer 
resistance to impact when the glass was pre-broken. To evaluate the 
strength and retention capabilities of pre-broken glazing, it was 
important that the windows did not unlatch or open during the impact. 
Therefore, NHTSA used modified MCI E/J-Series countermeasure latches in 
these tests to ensure the windows did not unlatch.
    After pre-breaking the glazing, the window was mounted on the test 
frame and the pre-broken glazing was impacted at the center of daylight 
opening in accordance with the Martec Study Conditions. Displacement of 
the impactor during the impact was measured. The results of the center 
of daylight opening impact tests under the Martec Study conditions on 
the MCI E/J-Series windows (double-glazed laminated and single-glazed 
laminated windows) with countermeasure latches for the different pre-
breaking methods are as follows:
     The windows remained latched in all the tests and there 
was no tearing in the PVB layer.
     Average maximum displacement of the impactor in center of 
daylight opening impacts were:
    --214 mm (8.4 inches) for fully pummeled pre-broken glazing.
    --184 mm (7.2 inches) (86 percent of fully pummeled glazing) for 50 
mm (2 inch) diagonally offset breakage pattern.
    --175 mm (6.9 inches) (82 percent of fully pummeled) for 75 mm (3 
inch) diagonally offset breakage pattern.
    --151 mm (5.9 inches) (71 percent of fully pummeled) for 75 mm (3 
inch) horizontally offset breakage pattern.
     The 50 (2 inch) and 75 mm (3 inch) breakage pattern 
methods are more objective than the fully pummeled method.
     There was little difference in maximum impactor 
displacements between the 50 (2 inch) and 75 mm (3 inch) diagonally 
offset pattern methods.
    --The 75 mm (3 inch) horizontally offset pattern method produced 
less maximum impactor displacement than the diagonally offset methods.
     Use of an electric staple gun (without the staples) to 
pre-break the glass panes was practical, allowed for single person 
operation, and did not produce tears in the PVB layer.
    NHTSA also tested single-glazed laminated windows with a thicker 
PVB interlayer to evaluate the impactor displacement as a function of 
the PVB interlayer thickness. The PVB thickness chosen for this test 
series was 1.52 mm (0.06 inches) (versus the 0.76 mm (0.03 inches) 
standard thickness). Center of the daylight opening impact tests under 
the Martec Study Conditions to pre-broken glazing (all four breaking 
methods: Fully pummeled, 75 mm (3 inch) diagonally offset pattern, 50 
mm (2 inch) diagonally offset pattern, 75 mm (3 inch) horizontally 
offset pattern) were conducted. The impacts did not produce any tearing 
in the PVB layer and the windows remained latched in

[[Page 27915]]

all the tests. The pre-broken glazing with the thicker PVB interlayer 
produced maximum displacements of the impactor that were on average 14 
percent less than similar impacts (center of daylight opening impact 
under Martec Study Conditions) into similarly pre-broken glazing 
production MCI E/J-series windows with standard thickness PVB 
interlayer.
5. Testing of MCI E/J-Series Fixed Windows (Martec Study Conditions)
    VRTC also tested fixed windows from the MCI E/J-series to assess 
their performance under the Martec Study Conditions. The fixed windows 
were attached to the E/J-series test frame in accordance with 
manufacturer's recommendations. Tests were conducted on unbroken 
single-glazed and unbroken and pre-broken double-glazed windows. 
Impacts were conducted near the primary locking mechanism (retaining 
clip) that locks the window to the frame and at the center of daylight 
opening.
     For tests conducted on unbroken glazing near the primary 
locking mechanism (retaining clip), the retaining clip bent backwards. 
The secondary clip bent but did not release, resulting in the window 
only partially opening.
     For tests conducted at the center of the daylight opening 
on unbroken glazing, the retaining clip bent, but the window opening 
result depended on the type of glazing impacted.
    --The single-glazed window fully opened.
    --The double-glazed window did not open.
     For tests conducted at the center of the daylight opening 
on pre-broken double-glazed windows, there was no damage to the 
retaining clips, and the windows did not open.

c. NHTSA's Large Bus Rollover Structural Integrity Research

    In support of the agency's proposal to improve the rollover 
structural integrity of motorcoaches and other large buses, among other 
things NHTSA evaluated ECE R.66 \43\ to see if the standard would 
address the safety needs NHTSA identified in that rulemaking.
---------------------------------------------------------------------------

    \43\ ECE R.66 defines ``superstructure'' as ``the load-bearing 
components of the bodywork as defined by the manufacturer, 
containing those coherent parts and elements which contribute to the 
strength and energy absorbing capability of the bodywork, and 
preserve the residual space in the rollover test.'' ``Bodywork'' 
means ``the complete structure of the vehicle in running order, 
including all the structural elements which form the passenger 
compartment, driver's compartment, baggage compartment and spaces 
for the mechanical units and components.'' (Footnote added.)
---------------------------------------------------------------------------

    In the ECE R.66 full vehicle test, the vehicle is placed on a 
tilting platform that is 800 mm (31.5 inches) above a smooth and level 
concrete surface. One side of the tilting platform along the length of 
the vehicle is raised at a steady rate of not more than 5 degrees/
second until the vehicle becomes unstable, rolls off the platform, and 
impacts the concrete surface below. The vehicle typically strikes the 
hard surface near the intersection between the sidewall and the roof. 
The encroachment of structures into a designated ``occupant survival 
space'' (defined by use of a survival space template) during and after 
the rollover structural integrity test is assessed.
    NHTSA evaluated several different models of OTRBs. Two older models 
were selected because they were representative of the range of roof 
characteristics (such as design, material, pillars, shape, etc.) of 
large bus roofs in the U.S. fleet. The vehicles selected were two 12.2 
meters (m) (40 feet) (ft) long model year (MY) 1992 MCI model MC-12, 
and two 12.2 m (40 ft) long MY 1991 Prevost model (Prevost) LeMirage 
buses. The most discernible difference between the MCI and Prevost 
models was that the Prevost had smaller side windows and more roof 
support pillars.
    NHTSA also tested a MY 2000 MCI bus, Model 102-EL3, that was 13.7 m 
(45 ft) in length. The agency tested this model because it was 
representative of many buses newer than the MCI and Prevost models. 
Newer buses are 13.7 m (45 ft) in length instead of 12.2 m (40 ft). The 
newer buses also tend to have larger windows than the earlier models.
    A detail report of the test program of the older buses is available 
in the docket.\44\ A report on the test of the newer bus can be found 
on NHTSA's Web site.\45\
---------------------------------------------------------------------------

    \44\ Docket No. NHTSA-2007-28793-0019.
    \45\ ``ECE Regulation 66 Based Research Test of Motorcoach Roof 
Strength, 2000 MCI 102-EL3 Series Motorcoach, NHTSA No.: MY 0800,'' 
October 1, 2009, Report No.: ECE 66-MGA-2009-001, http://www-nrd.nhtsa.dot.gov/database/aspx/searchmedia2.aspx?database=v&tstno=6797&mediatype=r&r_tstno=6797, 
Report 8. http://www-nrd.nhtsa.dot.gov/database/VSR/veh/QueryTest.aspx, Report 8. Step-by-step instructions on accessing the 
research report can be found in a memorandum in Docket No. NHTSA-
2007-28793-0025.
---------------------------------------------------------------------------

    In our research, high speed video cameras were used and transfer 
media were applied to each survival space template to determine if any 
portion of the vehicle interior had entered the occupant survival space 
during the rollover test. In addition, two Hybrid III (HIII) 50th 
percentile adult male anthropomorphic test devices (ATDs) (test 
dummies) were placed in the vehicle, on the opposite side of the 
impacted side of the bus, to measure injury potential and seat 
anchorage performance. One of the ATDs was belted and the other was 
unbelted. For the purposes of this advanced glazing NPRM, NHTSA 
reviewed the results from the evaluation to understand better the dummy 
occupant interaction with the windows during an elevated one-quarter 
turn roll event.
    The following summarizes the findings of the ECE R.66-based tests 
that are especially relevant to today's NPRM.
1. MY 1991 Prevost Bus
    The Prevost bus was equipped with ten laminated windows on each 
side of the bus. The windows were 815 mm (32 in) in width and 1,040 mm 
(41 in) in height. Four of the left windows and three of the right 
windows were designated emergency exit windows. The emergency exit 
windows were hinged at the top and latched at the bottom.
    Upon impact with the ground (left side of the bus), contact between 
the front survival space template and the left side window was made. 
The glass panes of the laminated glazing showed cracking and 
splintering. All of the glazings on the impact side (left) were 
retained in the windows. Three of the four left side emergency exit 
windows unlatched and lost retention during the impact but were held in 
the closed position by contact with the ground. The remaining left side 
emergency exit window remained latched during the impact with the 
ground.
    High speed film from the test indicated that the side windows 
located on the far side of the impact (right) underwent a substantial 
amount of flexion during the impact with the ground but remained 
intact. The flexion along with the inertia of the latching bar 
mechanism for this particular Prevost bus caused all three of the right 
side emergency exit windows to unlatch and open slightly. However, they 
were closed by gravity following the impact when the Prevost bus came 
to its final resting position. The two roof emergency exits also opened 
during the impact.
    The left pelvis of the unrestrained ATD seated far-side of the 
impact interacted with the inboard armrest prior to the bus impacting 
the ground. After the bus made contact with the ground, the top of the 
dummy's head made contact with the left window and the ATD came to rest 
straddling the third and fourth left windows from the front of the bus.

[[Page 27916]]

2. MY 1992 MCI Bus
    The MCI bus was equipped with seven laminated windows on each side. 
All of the windows were designated emergency exit windows with the 
exception of the right rearmost window. The windows were 1,310 mm (52 
in) in width and 685 mm (27 in) in height. The emergency exit windows 
were hinged at the top and latched at the bottom.
    Upon impact with the ground (left side of the bus), contact between 
the front survival space template and the left side window was made. 
The glass panes of the laminated glazing showed cracking and 
splintering. All of the glazings on the bus were fully retained in the 
windows.
    None of the emergency exit windows unlatched or opened during or 
after the ground impact. The roof emergency exits opened during the 
impact and a gap was visible between the roof panel and the emergency 
exit frame after the test.
    The left pelvis of the unrestrained ATD interacted with the inboard 
armrest during the bus impact with the ground. The top and back of the 
ATD head struck the left window as the bus impacted the ground, and the 
dummy came to rest on its head over the window.
3. MY 2000 MCI Bus
    The 2000 MCI 102-EL3 bus was equipped with seven laminated glass 
windows on each side. The front windows were fixed windows and the 
remaining windows were emergency exit windows. The majority of the 
windows were 1,564 mm (62 in) in width and 894 mm (35 in) in height, 
which is substantially larger than the previous two older buses (a 55 
percent increase in window area compared to the 1992 MCI model). The 
larger front windows were 1,564 mm (62 in) in width with a maximum of 
1,257 mm (50 in) in height, and the smaller rear windows were 1,042 mm 
(41 in) in width and 894 mm (35 in) in height.
    During the left-side impact with the ground, five of the seven 
right side glazings (toward the front of the bus) cracked and broke, 
and the window glazings fell into the occupant compartment during the 
test. The glazing from one of the right side front windows was retained 
by an overhead TV monitor and prevented the window pane from separating 
from its mounting gasket and falling into the bus. We believe that the 
glazing fell into the bus in this test, and not in the previous tests, 
because glazings on this bus are significantly larger, and presumably 
heavier, than the glazings used on the two older buses tested. The 
glazing in the last window near the rear cracked and broke but the 
window was retained and did not fall into the passenger compartment, 
possibly because the window was shorter in width than the other 
windows.
    The emergency exit window release handles for four of the right 
side windows rotated approximately 90 degrees; however, all emergency 
exit windows on both sides remained latched during the test. Both of 
the roof emergency exits opened during the test.
    All seven of the left side (impacted side of the bus) glazings 
remained fully retained in the windows after the rollover test.
    The unrestrained dummy's head first struck the luggage rack above 
the left side seats, and then the dummy's head hit the glazing of the 
third window from the front (left side of the bus). The dummy's left 
and right knees hit the seat back of the left side seats before hitting 
the center of the window. Its final resting position was on top of this 
window. The glazing remained intact and retained in the window.

V. Overview of Proposed Requirements

    In the 2013 seat belt final rule,\46\ NHTSA determined that a 
significant majority of fatalities in vehicles subject to the rule were 
attributable to rollovers and that more than three-quarters of rollover 
fatalities were attributable to ejections. In crashes in which the roof 
and bus structure remain intact, the main ejection portal for 
passengers was through the side windows.
---------------------------------------------------------------------------

    \46\ 78 FR 70416, November 25, 2013, supra.
---------------------------------------------------------------------------

    NHTSA is proposing performance requirements that the subject buses 
would have to meet by way of anti-ejection safety countermeasures. We 
are proposing to issue an FMVSS No. 217a to specify an impactor test of 
glazing material used in side and rear windows.\47\ In the tests, a 26 
kg (57 lb) impactor would be propelled from inside a test vehicle 
toward the window glazing at 21.6 km/h (13.4 mph). Each window would be 
subject to any one of three impacts, as selected by NHTSA in a 
compliance test: (a) An impact near a latching mechanism of an intact 
window; \48\ (b) an impact at the center of the daylight opening of an 
intact window; and (c) an impact at the center of the daylight opening 
of a pre-broken window. The impactor and impact speed in these proposed 
tests simulate the loading from an average size adult male impacting a 
window on the opposite side of a large bus in a rollover.
---------------------------------------------------------------------------

    \47\ A final rule could incorporate the proposed requirements 
into FMVSS No. 217, rather than in a separate FMVSS No. 217a. This 
NPRM shows the proposed requirements separately in FMVSS No. 217a 
for plain language purposes and the reader's convenience.
    \48\ For non-emergency exit fixed windows, the proposed test 
would be conducted at the location of one of the fixed latches or 
discrete attachment points. For fully rubber bonded or glued windows 
with no latch mechanisms, the test would be conducted along the 
center of the lower window edge one inch above the daylight opening 
periphery.
---------------------------------------------------------------------------

    The proposed performance requirements are as follows:
     In tests described in (a) and (b) in the above paragraph, 
the window would have to prevent passage of a 102 mm (4 inch) diameter 
sphere during the impact, and after the test. The agency would assess 
the window during the impact by determining whether any part of the 
window passes a reference plane defined during a pre-test set up 
procedure. These requirements would ensure that glazing is securely 
bonded to window frames, no potential ejection portals are created due 
to breaking of glass, and windows remain closed when impacted.
     In the test of (c) above, the maximum displacement of the 
impactor at the center of the daylight opening would be limited to 175 
mm (6.9 inches) for pre-broken glazing. This requirement in particular 
would drive the installation of advanced glazing. The requirement would 
also help ensure the advanced glazing reasonably retains occupants 
within the structural sidewall of the bus even when the glass 
surrounding the PVB interlayer is broken and ensures that no potential 
ejection portals are created during and after impact.
     Emergency exit latch protrusions may not extend more than 
one inch into the emergency exit opening of the window when the window 
is opened to the minimum emergency egress opening (allowing passage of 
an ellipsoid 500 mm (19.7 inches) wide by 300 mm (11.8 inches) high). 
This requirement would minimize the potential for the latch plate 
protrusions (or other projections) to hinder the emergency egress of 
passengers.
     Latches would have to remain functional following the 
impact test to ensure that occupants can open the emergency exits to 
egress the vehicle after a crash.
    Current regulations and industry standards for large buses do not 
adequately address window retention or ejection mitigation through 
glazing under dynamic occupant loading in rollovers.\49\ FMVSS No. 205, 
``Glazing

[[Page 27917]]

materials,'' industry standards,\50\ and various international 
regulations \51\ address the minimum strength and mechanical properties 
that certain safety glass (test samples) must possess, but they do not 
address window retention as a whole. FMVSS No. 217 has an ejection 
mitigation requirement by way of a quasi-static load application test 
(S5.1), but the test is not representative of the dynamic loading on 
glazing from an unrestrained adult male occupant during an OTRB 
rollover. The proposed FMVSS No. 227 requirements for bus structural 
integrity would require that windows (on the non-roll side) remain 
intact in their framing during the quarter turn, do not open up during 
the quarter turn, and have no openings large enough to admit passage of 
a 102 mm (4 inch) diameter sphere after the quarter turn. However, the 
forces that would be experienced by the windows in the proposed FMVSS 
No. 227 test are purely inertial and are not representative of any 
direct occupant loading from within the bus.
---------------------------------------------------------------------------

    \49\ On January 19, 2011, NHTSA issued a final rule (76 FR 3212) 
establishing a new FMVSS No. 226, ``Ejection mitigation,'' to reduce 
the partial and complete ejection of vehicle occupants through side 
windows in crashes, particularly rollover crashes. The standard 
applies to the side windows next to the first three rows of seats, 
and to a portion of the cargo area behind the first or second rows, 
in motor vehicles with a GVWR of 4,536 kg (10,000 lb) or less.
    \50\ ANSI Z26.1, ``Safety glazing materials for glazing motor 
vehicles and motor vehicle equipment operating on land highways,'' 
specifies performance tests and requirements for different types of 
glazing material regarding visibility, strength, and abrasion 
resistance. The specified tests do not evaluate the entire window 
for retention under loading conditions representing an unrestrained 
occupant impacting a window in a rollover event.
    \51\ European regulation, ECE R.43, ``Uniform provisions 
concerning the approval of safety glazing materials and their 
installation on vehicles,'' Australian Design rule, ADR 8/01, 
``Safety glazing material,'' and Japanese Industrial Standards, JI R 
3211, ``Safety glazing materials for road vehicles,'' are similar to 
FMVSS No. 205 and ANSI Z26.1. These standards only specify 
requirements on glazing characteristics but do not specify 
requirements for window retention under occupant loading.
---------------------------------------------------------------------------

    Thus, the requirements proposed in today's NPRM would fill a gap 
currently existing in NHTSA's motorcoach and large bus safety 
regulations. NHTSA recently issued a seat belt requirement \52\ to 
mitigate the risk of ejection. However, seat belt usage rates by 
motorcoach occupants are uncertain, and even if occupants are belted, 
there are risks associated with partial ejections. Advanced glazing in 
window openings and improved mountings would mitigate the risk of 
ejection of occupants who may not be restrained at the time of the 
crash, and the risk of partial ejections of both restrained and 
unrestrained occupants. Today's NPRM proposes requirements that would 
result in portal improvements by way of advanced glazing, consistent 
with the goals of the Motorcoach Safety Enhancement Act of MAP-21.
---------------------------------------------------------------------------

    \52\ 78 FR 70416 (November 25, 2013), supra.
---------------------------------------------------------------------------

    This NPRM is based on a number of research studies.
    NHTSA formulated this NPRM based on findings from the Martec study. 
Through computer simulation using the ECE R.66 rollover test, the 
Martec study established the forces that motorcoach occupants exert on 
the side window during rollover events, and the impact forces applied 
to the roof of the motorcoach. The Martec study also established the 
basis for the dynamic test procedure proposed today to test glazing 
materials and bonding techniques.
    NHTSA also designed this NPRM based on the findings of our 2011 and 
2013 follow-on testing of real-world motorcoach windows. The later 
study examined the exact failure mechanism(s) for side windows in a 
rollover event. We used the dynamic impactor device developed in the 
Martec study, along with its prescribed impact speed 21.6 km/h (13.4 
mph) and impactor mass 26 kg (57 lb), to evaluate modern bus windows 
that were representative of the fleet population. We obtained data 
about fleet baseline performance and the performance of various bonding 
methods and glazing materials, such as laminated glass and 
polycarbonates, tested on test frames representing side passenger 
window frames of actual motorcoaches.
    We also found in our 2013 testing that latch mechanisms on 
emergency windows routinely failed when the glazing near them was 
struck with the impactor. Failure of the latch caused the exit to open, 
posing an unreasonable risk of ejection in a rollover. These results 
indicated there is a safety need for a test that assesses the ability 
of the latches to remain closed when subjected to impactor loading. We 
were also able to modify some of the latch systems with simple designs, 
enabling the latch to stay closed when struck. This showed the 
practicability of meeting an ejection mitigation requirement when 
glazing is struck near the latch.
    NHTSA also based this NPRM on the findings from NHTSA's large bus 
structural integrity research program.\53\ In that program, NHTSA 
conducted ECE R.66 tests of a 1991 Prevost bus, a 1992 MCI bus and a 
2000 MCI bus. The 1991 Prevost and the 1992 MCI motorcoaches were able 
to retain the glazings on both the side of the bus impacting the ground 
and on the far side, showing the practicability of producing sufficient 
bonding techniques for glazing materials in motorcoaches.
---------------------------------------------------------------------------

    \53\ Supra.
---------------------------------------------------------------------------

    Additionally, the structural integrity test program showed that bus 
design can influence glazing retention. In the test of the 2000 MCI 
bus, during the left-side impact with the ground five of the seven 
glazings on the right side of the bus cracked and broke, and the window 
glazings fell into the occupant compartment during the test. We believe 
that the glazing fell into the bus in this test, and not in the 
previous tests of the 1991 Prevost and the 1992 MCI, because glazings 
on the 2000 MCI bus were significantly larger, and presumably heavier, 
than the glazings used on the two older buses tested. The bonding 
technique was not strong enough to support the heavier glazings. The 
glazing in the last window near the rear of the 2000 MCI bus cracked 
and broke but the window was retained and did not fall into the 
passenger compartment, possibly because the window was shorter in width 
than the other windows.
    NHTSA's structural integrity testing showed good performance by 
laminated glazing. The 1991 Prevost bus was equipped with ten laminated 
windows on each side of the bus. In the ECE R.66 test, upon impact with 
the ground (left side of the bus), the glass panes of the laminated 
glazing on the left side showed cracking and splintering but were 
retained in the windows. The 1992 MCI bus was equipped with seven 
laminated windows on each side. Upon impact with the ground (left side 
of the bus), the glass panes of the laminated glazing on the left side 
showed cracking and splintering. All of the glazings on the bus were 
fully retained in the windows.
    Studies show that bus glazings are exposed to multiple and chaotic 
impacts in a rollover. In the Martec study, the simulation showed 
glazing struck by the unbelted passenger occupant before the bus was 
completely on its side. In NHTSA's structural integrity tests, the 
unrestrained ATD was basically freefalling from the seat as the bus 
tipped over, and did not contact the side windows until after the bus 
had already impacted and made contact with the ground surface. In the 
test of the 1992 MCI bus, the top and back of the restrained ATD head 
struck the third window from the front of the bus on the left side as 
the bus impacted the ground. The window glazing cracked and splintered 
as the laminated glazing hit the ground. The test dummy came to rest on 
its head over this window which remained intact after the test.

[[Page 27918]]

    Because glazings are subject to multiple, unpredictable impacts 
from occupant and/or ground contact in a rollover, NHTSA has 
tentatively determined that the dynamic impact test proposed today 
should include a test set-up specification and method that involves 
pre-breaking the glazing prior to the impactor test. Pre-breaking the 
glazing mimics a real-world condition, as the side window glazing is 
often broken when the bus contacts the ground. With advanced glazing, 
the procedure would likely result in the outside glass breaking without 
deforming the laminate. With tempered (non-advanced) glazing, the 
procedure would likely result in the glazing shattering into fragments. 
As a result, to meet a final rule resulting from this NPRM, buses 
covered by the rule would likely use laminated glazing, and not 
tempered glazing, to meet the requirements proposed today.

VI. Test Procedure Specifications

a. Impactor

    NHTSA proposes to use the impact test device developed in the 
Martec study, supra. That study determined that a mid-size adult male 
would strike the glazing with his head, followed closely by his 
shoulder/torso. Simulations also showed that the impact area between 
the bus occupant and the window glazing was primarily along the side of 
the occupant.
    The proposed impactor design is as outlined in Figure 3, 
representing the torso of the SID. The mass of the impactor is 26 kg 
(57 lb), representing the effective mass measurements from the 
numerical analysis of the Martec study. A spring with the appropriate 
stiffness (258 N/m) was used to replicate compression of the thorax. 
The impactor face is a rectangle measuring 177 mm x 212 mm (7 inch x 
8.3 inch) with rounded corners. A shoulder foam part from the SID is 
affixed to the impactor face to replicate the compression of the foam 
located beneath the dummy's chest jacket (Figure 3).

b. Test Speed

    The impact speed in these proposed tests simulates the loading from 
an average size adult male impacting a window on the opposite side of a 
large bus in a rollover. In the Martec study, computer modeling of a 
bus rollover predicted the loads on the bus windows from a mid-size 
adult male occupant. The Martec study found that the impact velocity of 
the occupant striking the glazing with his head, followed closely by 
his shoulder/torso, could be as high as 6.0 m/s (21.6 km/h or 13.4 
mph). We propose to use this impact speed of 21.6 km/h (13.4 mph) for 
each of the proposed dynamic impact tests.

c. ``Portal'' Improvements

    The Motorcoach Enhanced Safety Act directs the agency to consider 
requiring advanced glazing standards for ``each motorcoach portal'' 
(section 32703(b)(2)). The Act defines ``portal'' as ``any opening on 
the front, side, rear, or roof of a motorcoach that could, in the event 
of a crash involving the motorcoach, permit the partial or complete 
ejection of any occupant from the motorcoach, including a young child'' 
(section 32702(9)).
    We have considered requiring advanced glazing standards for each 
motorcoach portal in accordance with the Act, and have decided, based 
on accident data, to apply this NPRM to the bus side and rear windows 
and to glass panels/windows on the roof. We are not applying the 
proposed requirements to the front windshield, or to emergency exit 
doors, service doors, or roof hatches. Accident data of real world 
rollover incidents indicate that passenger ejections are not occurring 
from the front windshield or emergency or service doors. We are aware 
of only one incident of a real world rollover crash involving a front 
windshield ejection, and that was a non-fatality.\54\
---------------------------------------------------------------------------

    \54\ The crash occurred in Victory, NY. The front right occupant 
was ejected only after the windshield had broken out during a 
frontal collision.
---------------------------------------------------------------------------

    To the extent emergency roof exits are opening during the impact 
with the ground, NHTSA's rulemaking on large bus rollover structural 
integrity will address that ejection risk. NHTSA has proposed in that 
rulemaking to require emergency exits to remain shut during the 
rollover test, and to be operable in the manner required under FMVSS 
No. 217 after the test. Those proposed requirements would ensure that 
roof hatches do not open during a quarter-turn rollover, at minimum, 
from the inertial loading of its own weight.
    We have applied the proposed advanced glazing requirements to the 
portals we believe pose a valid risk of ejection. We estimate that side 
bus windows account for about 80 percent of portals (potential ejection 
routes) on buses, which presents a high exposure risk to potential 
ejection. Given this exposure, this NPRM will focus advanced glazing 
and other ejection mitigation efforts on the bus side and rear windows 
(emergency and non-emergency exits). In addition, we have recently 
become aware of some motorcoaches equipped with glass roofs or glass 
panel ceilings to provide an enhanced view for bus passengers. These 
glass panels/windows on roofs can become ejection portals if advanced 
glazing is not used. Therefore, we propose to apply this NPRM to roof 
glass panels/windows as well, assuming they are of a minimum size.
    We also propose to apply this NPRM to rear windows. We recognize 
that OTRBs typically have the bus engine in the rear, and therefore 
usually have no window on the rear of the bus. However, nothing 
precludes bus designs from having windows in the rear of the bus that 
could be potential ejection portals. However, to be subject to the 
proposed requirements, the windows would have to be a minimum size.
    A minimum size criterion would thus apply to side and rear windows, 
and to roof glass panels/windows. The criterion would address 
limitations of testing with the impactor. The window would be tested if 
it is large enough to fit the impactor face plus a 25 mm (1 inch) 
border around the impactor face plate edge without contact with the 
window frame. The dimensions of the dynamic impactor we propose to use 
are 177 mm by 212 mm (7 inches by 8.3 inches). Using the 8.3 inches 
dimension of the dynamic impactor, the proposed dynamic test procedure 
would be applicable to a side window whose minimum dimension measured 
through the center of its area is (280 mm) (11 inches) or greater. (The 
rationale for the 280 mm (11 inches) is provided below in the next 
paragraph.) The 25 mm (1 inch) clearance is needed to make sure we are 
testing the strength of the glazing and bonding in retaining the 
impactor and that of the latches withstanding the impact, and not the 
strength of the window frame. If the impactor were to strike the window 
frame structure, the impactor could be partially restrained by the 
window frame structure and the performance of the glazing and bonding 
would not be fully assessed.
    The proposed exclusion is consistent with FMVSS No. 217, which 
currently excludes from S5.1's window retention requirements ``a window 
whose minimum surface dimension measured through the center of its area 
is less than 8 inches'' (S5.1.2). FMVSS No. 217 uses a head form with a 
76 mm (3 inch) spherical radius (152 mm (6 inch) diameter) to apply the 
quasi-static force application (S5.1). We are proposing that the new 
dynamic test be applicable only to bus windows with a proportional 
minimum surface dimension. That is, using the wider 212 mm (8.3 inch) 
dimension of the dynamic impactor, the proposed dynamic test procedure 
would be

[[Page 27919]]

applicable to a side window whose minimum dimension measured through 
the center of its area is 280 mm (11 inch) or greater.\55\
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    \55\ (6 inch/8 inch) = (8.3 inch/X inch), therefore (X = 11 
inch).
---------------------------------------------------------------------------

d. Definition of Daylight Opening

    This NPRM proposes a procedure for testing glazing in each side and 
rear window opening and roof glass panels/windows. To describe 
precisely where the impactor would be targeted on the glazing, we would 
first define how the ``daylight opening'' (window opening) would be 
determined. For side windows, the ``daylight opening'' would be the 
locus of all points where a horizontal line, perpendicular to the 
vehicle longitudinal centerline, is tangent to the periphery of the 
opening. For rear windows, the ``daylight opening'' would be the locus 
of all points where a horizontal line, parallel to the vehicle 
longitudinal centerline, is tangent to the periphery of the opening. 
For roof glass panels/windows, the ``daylight opening'' would be the 
locus of all point where a vertical line is tangent to the periphery of 
the opening. The periphery would include surfaces 100 mm (3.94 inches) 
inboard of the inside surface of the window glazing and 25 mm (0.98 
inches) outboard of the outside surface of the window glazing. The 
periphery would exclude any flexible gasket material or weather 
stripping, grab handles, and any part of a seat.
    This definition of daylight opening would be similar to the 
definition of ``side daylight opening'' in FMVSS No. 226, ``Ejection 
mitigation.'' As explained in the FMVSS No. 226 rulemaking, flexible 
gasket material, weather stripping and the like are excluded from the 
``daylight opening'' definition because the flexible material is 
unlikely to impede occupant ejection through the opening.\56\ The 
glazing underlying the flexible material should be considered part of 
the daylight opening for testing purposes, thus subject to impactor 
testing. The exclusion results in keeping the glazing area that NHTSA 
may test as large as possible.
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    \56\ 74 FR 63180, 63205 (December 2, 2009).
---------------------------------------------------------------------------

    Grab handles would be excluded from the definition for the same 
reasons explained in the FMVSS No. 226 rulemaking.\57\ In a rollover, 
grab handles are unlikely to have any effect mitigating the likelihood 
of ejection since occupants will move toward the daylight opening from 
many different angles. Grab handles are unlikely to contribute toward 
lowering the risk of occupant ejection through the window (i.e., they 
do not lower the chance of ejection because they would block the 
opening). Thus, we believe it would not make sense for the test 
procedure to allow grab handles to define the area of glazing tested.
---------------------------------------------------------------------------

    \57\ Final rule; response to petitions for reconsideration, 78 
FR 55138, 55152 (September 9, 2013).
---------------------------------------------------------------------------

    We note that there currently is a definition of the term ``daylight 
opening'' in FMVSS No. 217 (S4). The term is defined as: ``the maximum 
unobstructed opening of an emergency exit when viewed from a direction 
perpendicular to the plane of the opening.'' The term was inadvertently 
added to the standard by a May 9, 1995 final rule (60 FR 24562); the 
term is not used in any other part of the regulatory text. We propose 
to delete the term in S4.

e. Glass Breakage Procedure

    NHTSA is proposing a breaking specification and method that 
involves punching holes in the glazing, to simulate the damage the 
glazing could experience in a rollover prior to impact by an 
occupant.\58\ The holes would be punched at set distances on both the 
interior and exterior glass plies of the laminated glazing. The window 
breaking procedure would damage but not destroy laminated glazing, 
while it would obliterate tempered glazing. Since tempered glazing 
would be obliterated, a final rule resulting from this proposal would 
have the effect of prohibiting manufacturers from having bus windows 
made solely from tempered glazing.
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    \58\ In NHTSA's developmental testing, the agency found that 
using an electric staple gun without any staples worked well. Holes 
punched with the unloaded electric staple gun did not penetrate 
through the PVB interlayer. See ``Motorcoach Side Glazing Retention 
Research,'' November 2013, supra.
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    NHTSA studied various methods to break the glazing prior to the 
impact tests, including impacts with a hammer (pummeled), using an 
automatic center punch, and an unloaded electric staple gun.\59\ The 
agency also studied several patterns of breakage (75 mm (3 inch) 
diagonally offset, 75 mm (3 inch) horizontally offset, and 50 mm (2 
inch) diagonally offset grids).\60\ The study is discussed in NHTSA's 
``Motorcoach Side Glazing Retention Research,'' November 2013, supra.
---------------------------------------------------------------------------

    \59\ A Duo Fast Model EWC electric staple gun without staples 
was used. With the front nose opening of the staple gun normal to 
the glazing, the staple gun applied a 12.7 mm (0.5 inch) line load 
with an average force of 4,200 Newton (N) (994 lb) (standard 
deviation = 850 N (191 lb)) when fired. This force was sufficient to 
break the glass without any damage to the inner laminate layer.
    \60\ The breakage pattern developed in the ejection mitigation 
regulation (FMVSS No. 226) where the 75 mm (3 inch) pattern is 
``horizontally offset'' was also studied. NHTSA found that the 
automatic center punch used in FMVSS No. 226's procedure was not 
practical for large bus windows.
---------------------------------------------------------------------------

    In NHTSA's study, the Martec study impact tests were performed on 
broken glazing with the impactor striking the window at the center of 
the daylight opening, as measured on the interior window frame. Not 
surprisingly, the results showed that more glass breakage (maximum 
breakage was achieved in the pummeled test) yields more peak impactor 
displacement. However, the 75 and 50 mm (3 and 2 inch) diagonally 
offset matrix hole punching methods were found to be more controllable 
and objective than the pummeling method, while also creating extensive 
breakage patterns. Thus, NHTSA decided to incorporate the hole punching 
method rather than the pummeling method in the proposed test procedure.
    Results also indicated that there does not appear to be a 
significant difference in displacement of the impactor between the 75 
and 50 mm (3 and 2 inch) diagonally offset patterns. Yet, the 75 mm (3 
inch) diagonally offset grid pattern has 53 percent fewer punch holes 
compared to the 50 mm (2 inch) diagonally offset grid pattern, i.e., 
the 75 mm (3 inch) diagonally offset pattern would require less than 
half the number of hole punches compared to the 50 mm (2 inch) pattern. 
Additionally, the 75 mm (3 inch) diagonally offset pattern resulted in 
glazing performance that was closer to the 50 mm (2 inch) diagonally 
offset and pummeled glazing tests, compared to the 75 mm (3 inch) 
horizontally offset grid pattern. For these reasons, NHTSA has chosen 
the 75 mm (3 inch) diagonally offset grid pattern to incorporate into 
the proposed test procedure.
    The first step in the test procedure would be to mark the glazing 
surface on the occupant interior glass in a horizontal and vertical 
grid of points separated by 75 mm (3 inches), with the first point 
coincident with the geometric center of the daylight opening. Next, the 
grid on the opposite side of the glazing would be marked. For most 
glazing, the grid on the opposite side of the glazing would be 
staggered to avoid tearing the PVB interlayer. For laminates, ``the 
opposite side of the glazing'' means the opposing glass ply directly 
opposite of the PVB interlayer. ``Staggered'' means that the 75 mm (3 
inch) offset pattern has a 75 mm x 75 mm (3 inch x 3 inch) pattern on 
the occupant interior glass and the same pattern, offset by 37.5 mm 
(1.5 inch) horizontally and vertically, on the outside exterior glass 
surface.
    For windows that are a single-pane unit, we would use the grid 
pattern on the occupant space interior surface and

[[Page 27920]]

the staggered grid pattern on the outside exterior surface of the glass 
pane.
    For double-glazed windows, we would use a grid pattern on the 
occupant space side of the interior pane and on the outside of the 
exterior pane. For double-glazed windows that consist of one pane of 
tempered glass, that pane would be broken and removed, and the 
remaining glass pane (that is not of tempered glass) would be pre-
broken on both sides (occupant interior and outside exterior) with the 
grid and staggered grid patterns, respectively. For double-glazed 
windows that do not consist of any tempered glass pane, it would not be 
practical to apply the 75 mm (3 inch) pre-break pattern to the 
insulated surface (inside the air gap) of the individual glass panes. 
In these cases in which neither pane is tempered glass, both the 
occupant space side of the interior pane and the outside of the 
exterior pane would be broken in the grid pattern, but the patterns 
would not be offset (one side would not use the staggered pattern) due 
to a lack of need. That is, for those windows there would be little 
likelihood of tearing the PVB interlayer even when the patterns are not 
offset.
    The agency envisions breaking the defined grid points using an 
unloaded electric staple gun, since the device worked well for that 
purpose in our developmental testing. The staple gun we use would apply 
12.7 mm (0.5 inch) line load (with a thickness of 1.3 mm (0.05 inches)) 
(the size of a standard staple) on the glazing with a force in the 
range of 3,500 Newtons (N) (787 lb) to 5,000 N (1,124 lb) when the 
front nose opening of the staple gun is held normal to the glazing. 
These staple gun specifications are designed so as to break the glass 
with a single punch without producing tears in the PVB interlayer. 
Holes would be punched in the glazing starting with the inside surface 
of the glazing, and starting with the forward-most, lowest hole in the 
pattern. We would continue punching holes 75 mm (3 inches) apart, 
moving rearward on the bus. When the end of a row is reached, we would 
move to the most forward hole in the next higher row, 75 mm (3 inches) 
from the punched row. After completing the holes on the inside surface, 
we would repeat the process on the outside surface.
    When punching a hole, we would place a 100 mm (4 inch) by 100 mm (4 
inch) piece of plywood on the opposite side of the glazing as a 
reaction surface against the punch. If a particular window were 
constructed such that the inner laminated material is penetrated or 
damaged, the procedure would not be halted or invalidated. The impactor 
test would be conducted at the conclusion of the glazing breakage 
procedure. If punching a hole causes the glazing to disintegrate, as 
would occur when testing tempered glazing, the procedure would be 
halted for that item of glazing and the impactor test would be 
conducted on what glazing, if any, remains. If there is no glazing 
remaining after the hole-punching procedure, there would be a failure 
to comply since the window would not be able to restrain the impactor 
or prevent passage of the 102 mm (4 inch) diameter sphere.

VII. Performance Requirements

    NHTSA proposes to specify performance requirements for windows 
comprised of unbroken and broken glazing when the glazing is subjected 
to impactor testing. The impactor would be propelled along a horizontal 
plane for side and rear windows and would be propelled along a vertical 
plane for roof glass panels/windows.

a. Unbroken Glazing

    The amendments proposed by this NPRM would require buses to meet 
performance requirements during and after the impactor test. Each 
unbroken window would be subject to either of the following two 
impacts, as selected by NHTSA in a compliance test: (a) An impact near 
a latching mechanism,\61\ and (b) an impact at the center of the 
daylight opening. The tests would ensure that glazing is securely 
bonded to window frames and that glass breakage during impact does not 
result in a potential ejection portal. In addition, the test near a 
latching mechanism would ensure that the latch system is able to keep 
the window closed when subjected to direct occupant loading, so as not 
to become a potential ejection portal. In NHTSA's motorcoach side 
glazing retention research program, production windows from all three 
manufacturers resulted in window opening during the impact.
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    \61\ For non-emergency exit fixed windows, the proposed test 
would be conducted at the location of one of the fixed latches or 
discrete attachment points. For fully rubber bonded or glued windows 
with no latch mechanisms, the test would be conducted along the 
center of the lower window edge one inch above the daylight opening 
periphery.
---------------------------------------------------------------------------

    We are proposing that windows (a) prevent passage of a 102 mm (4 
inch) diameter sphere during the impact, and (b) be sturdy enough such 
that there are no openings after the test that allow the passage of the 
sphere when a force of no more than 22 N (5 lb) is applied with the 
sphere at any vector in a direction from the interior to the exterior 
of the vehicle. The requirement described in (b) is a simple one based 
on a longstanding requirement currently in S5.1 of FMVSS No. 217. The 
compliance test for S5.1 of Standard No. 217 involves a compliance 
technician probing the window with the sphere. NHTSA would assess 
compliance with the requirement in (b) above using the same basic 
procedure.
    However, the requirement in (a) is more challenging. Because it is 
impractical to probe for openings with the 102 mm (4 inch) sphere 
during a dynamic test, NHTSA is proposing a requirement that is 
premised on the concept of passage of the sphere, but is one that can 
be more easily assessed in a dynamic test. This requirement would be 
that during the impactor test, no portion of the window (excluding 
glazing shards) may displace past a specified reference plane that is 
determined in a pre-test procedure. The procedure is explained below.
Ejection Reference Plane
    In NHTSA's impactor test of glazing near a latching mechanism and 
in the impactor test of glazing at the center of daylight opening, an 
``ejection reference plane'' would be determined prior to the test. The 
plane would be based on the passage of a 102 mm (4 inch) diameter 
sphere through a potential ejection portal of the window. We would 
require that no part of the window (excluding glazing shards) may pass 
this ``ejection reference plane'' during the dynamic impact test. If 
any part of the window frame passes the plane, there would be a failure 
to comply.
    For side windows, the ``ejection reference plane'' is a vertical 
plane parallel to the longitudinal vertical center plane of the bus 
passing through a point located at a lateral distance of 102 mm (4 
inches) from the lateral most point on the glazing and surrounding 
frame, with the window in the closed position.
    For rear windows, the ``ejection reference plane'' is a vertical 
plane perpendicular to the longitudinal vertical center plane of the 
bus passing through a point located at a longitudinal distance of 102 
mm (4 inches) from the rear most point on the glazing and surrounding 
frame, with the window in the closed position.
    For roof glass panels/windows, the ``ejection reference plane'' is 
a horizontal plane passing through a point located at a vertical 
distance of 102 mm (4 inches) from the highest point on the glazing and 
surrounding frame, with the window/panel in the closed position.

[[Page 27921]]

Displacement Limit of 102 mm (4 inches)
    The proposed performance requirements are built on preventing 
passage of a 102 mm (4 inch) diameter sphere. The principle underlying 
the 102 mm (4 inch) displacement limit is to prevent gaps or openings 
to form in advanced glazing through which occupants (``including 
children,'' states MAP-21 at Sec.  32703(b)(2)) can be partially or 
totally ejected. A 100 mm (3.94 inch) performance limit is used in 
several regulations relating to occupant retention. FMVSS No. 217 
already requires manufacturers to ensure that each piece of glazing and 
each piece of window frame be retained by its surrounding structure in 
a manner that prevents the formation of any opening large enough to 
admit the passage of a 102 mm (4 inch) diameter sphere under a 
specified force. The 102 mm (4 inch) value is also used in FMVSS No. 
206, ``Door locks and door retention components'' (49 CFR 571.206). In 
FMVSS No. 206, the door is loaded with 18,000 N (4,047 lb) and the 
space between the interior of the door and the exterior of the door 
frame must be less than 100 mm (3.94 inches).
    In addition, the 102 mm (4 inch) limit is used in FMVSS No. 226, 
``Ejection mitigation'' (49 CFR 571.226). It was noteworthy to NHTSA 
when developing the NPRM proposing the standard that a value of 
approximately 100 mm is used by the International Code Council (ICC) in 
developing building codes used to construct residential and commercial 
buildings. The ICC 2006 International Building Code and 2006 
International Residential Code require guards to be placed around areas 
such as open-sided walking areas, stairs, ramps, balconies and 
landings. The guards must not allow passage of a sphere 102 mm (4 
inches) in diameter up to a height of 864 mm (34 inches). NHTSA noted 
that the ICC explains in the Commentary accompanying the Codes that the 
102 mm (4 inch) spacing was chosen after considering information 
showing that the 102 mm (4 inch) opening will prevent nearly all 
children 1 year in age or older from falling through the guard. That 
information helped NHTSA decide on a 100 mm (3.94 inch) limit for the 
displacement of the head form impactor used in FMVSS No. 226.
    NHTSA requests comment on the linear displacement limit of 100 mm 
(3.94 inch) as an appropriate value.

b. Broken Glazing

    Under this NPRM, each window would have to meet performance 
requirements during and after an impact while pre-broken prior to the 
test. The impact would be at the center of the daylight opening of the 
window. The maximum displacement of the impactor would be limited to 
175 mm (6.89 inches). The 75 mm (3 inch) diagonally offset pattern 
would be used to pre-break the glazing with an unloaded electric staple 
gun.
    This proposed test is to better simulate a real-world test 
condition. As explained above in this preamble, the proposed dynamic 
test simulates the loading of an unrestrained far-side 50th percentile 
adult male passenger falling onto and loading the roll-side window. The 
roll-side glazing may not always be intact prior to this occupant 
loading. For instance, the glazing could break or shatter from objects 
interior or exterior to the bus, torsion or deformation of the bus 
structure, or even from the roll-side seated passenger loading prior to 
the far-side occupant loading. This proposed test would evaluate the 
strength and retention capabilities of pre-broken glazing (particularly 
the plastic interlayer of laminated glass) to ensure that there is 
enough strength left in the glazing to withstand the loading of the 
occupant and to retain the occupant within the bus. In addition, the 
window would be prohibited from having any opening after the test that 
would allow passage of the 102 mm (4 inch) diameter sphere.
    NHTSA requests comments on the proposed 175 mm (6.9 inch) impactor 
displacement value. The proposed 175 mm (6.9 inch) limit was chosen in 
the interest of practicability, potential costs, and safety need. The 
175 mm (6.9 inch) value is the average displacement from the two tests 
of single-glazed laminated windows (standard thickness PVB laminates 
0.76 mm (0.03 inch) layer), that were pre-broken using the 75 mm (3 
inch) diagonally offset grid. However, the MCI E/J-series was the only 
bus model tested at VRTC that offered production windows with a 
laminated glass configuration. Therefore, the proposed requirement is 
based solely on the MCI E/J windows that were tested. We seek comments 
on whether 175 mm (6.9 inch) maximum impactor displacement is an 
appropriate value for other bus window designs and window dimensions.
    Comments are also requested on the practicability, costs and 
benefits of a lower impactor displacement limit, such as 146 mm (5.75 
inches). One hundred forty-six (146) mm (5.75 inches) is the average 
displacement of the impactor in the center of daylight opening impacts 
under the Martec Study Conditions of pre-broken (using the 75 mm (3 
inch) diagonally offset pattern) MCI E/J-Series glazing with the 
thicker 1.52 (0.06 inches). We observe that a 100 percent increase in 
the PVB interlayer thickness only resulted in a 14 percent reduction of 
average impactor displacement.

VIII. Other Proposed Requirements

    Other requirements are also proposed for emergency exit latches and 
other related release mechanisms.

a. Latch Protrusions

    NHTSA proposes to amend FMVSS No. 217 to specify that emergency 
exit latches and other related release mechanisms not protrude more 
than 25 mm (1 inch) into the opening of an emergency exit when the 
window is opened as described in S5.4.1 of the standard (when the 
window is opened to the minimum emergency egress opening (allowing 
passage of an ellipsoid 500 mm (19.7 inches) wide by 300 mm (11.8 
inches) high)).
    This requirement would respond to Recommendation No. H-11-37 of the 
NTSB, supra, which NTSB issued after investigating an August 5, 2010 
multi-vehicle collision school bus crash in Grey Summit, Missouri, in 
which egress from emergency windows was hindered by protruding 
latches.\62\ H-11-37 states:
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    \62\ Several passengers in the lead school bus, and a witness 
who assisted in the evacuation, stated in post-crash interviews that 
emergency egress was hindered by the design of the emergency exit 
window. Particularly, the 102 mm (4 inch) by 76.2 mm (3 inch) 
emergency release latch plate for the emergency exit window was 
elevated about 25.4 mm (1 inch) from the window base and snagged the 
clothing of several passengers as they were exiting through the 
window opening.

Modify FMVSS No. 217 or the corresponding laboratory test procedure 
to eliminate the potential for objects such as latch plates to 
protrude into the emergency exit window opening space even when the 
protrusion still allows the exit window to meet the opening size 
---------------------------------------------------------------------------
requirements.

    We seek comment on what an appropriate maximum latch protrusion 
might be. The MCI E/J and Van Hool latches (both production and 
countermeasure designs) met the proposed 25 mm (1 inch) height 
protrusion limit, while the Prevost latch (both production and 
countermeasure design) did not.\63\
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    \63\ Although the striker posts on the MCI E/J latch protrude 
less than 25.4 mm (1 inch) into the emergency exit opening, the MCI 
E/J latching system also includes the guide cams (Figure 43) which 
protrude more than 25.4 mm (1 inch) into the emergency exit opening.
---------------------------------------------------------------------------

    The maximum latch plate protrusion requirement would be applicable 
to the buses to which the impactor tests would apply.\64\ This NPRM's 
proposed impact

[[Page 27922]]

tests on the glazing would require emergency exit latches to be 
sufficiently strong to pass the proposed dynamic impactor test 
requirements at the near latch (and even center of daylight opening) 
impact. The latch plates on those buses would likely need to be 
redesigned to meet the proposed dynamic impact requirements, so new 
designs for latch plates that do not protrude past the allowable limit 
can be readily incorporated into manufacturers' redesigns at the same 
time.
---------------------------------------------------------------------------

    \64\ New OTRBs (except school buses) and all new non-OTRBs with 
a GVWR greater than 11,793 kg (26,000 lb) that are not transit 
buses, school buses or perimeter seating buses.
---------------------------------------------------------------------------

    However, NHTSA is also proposing to extend the maximum latch plate 
protrusion requirement to other buses as well. NTSB recommendation H-
11-37 was issued as a result of a school bus crash. Thus, NHTSA is 
proposing to extend the proposed requirement to school buses also. In 
addition, since this proposal of limiting the size of emergency exit 
latch plate protrusions is intended to mitigate hindrance from the 
window latches during emergency egress, we request comment on the 
merits of requiring all buses to which FMVSS No. 217 applies to meet 
the requirement. Such a requirement could enhance emergency egress from 
all buses.

b. Latch Workable After Impact

    The NPRM proposes to require that latches be functional in 
accordance to the emergency egress requirements of FMVSS No. 217 
following the impact tests. This requirement is intended to increase 
the likelihood that, after a rollover event, all emergency exits are 
operable to enable bus occupants to egress out of the bus. Requiring 
emergency windows to remain operable after the impact test would 
increase the likelihood that these windows are operable in real world 
rollover events where occupants may load the window before the bus 
comes to rest. A similar requirement was also proposed in the August 6, 
2014 NPRM for FMVSS No. 227, ``Bus rollover structural integrity,'' 
where the emergency exits are required to remain shut during the bus 
rollover test and be operable in the manner required under FMVSS No. 
217 after the test.

IX. Applicability

    NHTSA proposes to apply the proposed dynamic impact test 
requirements to generally the same group of vehicles that would be 
covered by the structural integrity NPRM.\65\ We have tentatively 
concluded that both rulemakings would apply to high-occupancy vehicles 
associated with unreasonable risk of fatal rollover involvement, and 
that these vehicles are generally buses with a GVWR greater than 11,793 
kg (26,000 lb).
---------------------------------------------------------------------------

    \65\ 79 FR 46090 (August 6, 2014), supra.
---------------------------------------------------------------------------

    The buses that would be covered would be (a) new OTRBs (regardless 
of GVWR), pursuant to the Motorcoach Enhanced Safety Act of MAP-21, and 
(b) all new buses other than OTRBs, with a GVWR greater than 11,793 kg 
(26,000 lb).\66\ The reasons for this two-prong approach towards 
determining applicability are discussed in detail in the structural 
integrity NPRM, supra. See 49 FR at 46102-46105. The approach would be 
to cover all of the buses covered by MAP-21 and all of the buses with 
similar safety risks as the buses covered under MAP-21.
---------------------------------------------------------------------------

    \66\ Transit buses, school buses, and perimeter-seating buses 
would be excluded from the standard under this latter category.
---------------------------------------------------------------------------

    Our proposed applicability of this NPRM also reflects a holistic 
approach toward adopting anti-ejection safety countermeasures for 
unbelted passengers. NHTSA's strategy has been first to seek 
improvements to the rollover structural integrity of motorcoaches (roof 
strength and crush resistance) and then to pursue measures that would 
drive use of advanced glazing. This ordered approach is based on 
findings from the Martec study that the integrity of the bus structure 
has a profound impact on the effectiveness of the glazing. That is, in 
the absence of a threshold of requisite performance for bus structural 
integrity, a twisting motion of a bus in a rollover could simply pop 
out any advanced glazing used in the windows and negate the potential 
benefits of the glazing.
    Thus, to better ensure that the full benefits of anti-ejection 
countermeasures such as advanced glazing would be realized, we first 
focused on improving bus structural integrity and the strength of side 
window mountings by way of the large bus structural integrity NPRM. 
Improvements to the bus structure would increase the likelihood that 
bus glazing will be retained in their mountings in a rollover. Next in 
our strategy is issuance of today's NPRM, which has performance 
requirements that would increase use of advanced glazing that prevent 
partial or complete ejection of motorcoach passengers and further 
ensure the integrity of glazing mounting. Since today's NPRM builds on 
the 2014 rollover structural integrity NPRM, we propose to apply 
today's dynamic impact test to the vehicles subject to the 2014 NPRM.
    However, prison buses were among the buses to which NHTSA proposed 
applying the structural integrity requirements. We have tentatively 
determined that an advanced glazing standard would not be appropriate 
for prison buses since these buses typically have bars over the 
windows. The bars would impede the impactor. FMVSS No. 217 currently 
does not apply to ``buses manufactured for the purpose of transporting 
persons under physical restraint'' (S3).
    Further, note that today's NPRM proposes requirements limiting how 
far emergency exit latches may protrude into the exit space. We propose 
applying the requirement to the buses to which NHTSA proposed would be 
subject to the 2014 rollover structural integrity NPRM, and also to 
school buses. In addition, we are considering applying the proposed 
maximum emergency exit latch protrusion requirements to all buses 
governed under FMVSS No. 217. We believe that vehicles would not need 
to have their roofs and side structure improved to meet the latch 
protrusion requirements. Comments are requested on this issue.

X. Retrofitting

    The Secretary of Transportation has authority to promulgate safety 
standards for ``commercial motor vehicles and equipment subsequent to 
initial manufacture.'' \67\ The Office of the Secretary has delegated 
authority to NHTSA to ``promulgate safety standards for commercial 
motor vehicles and equipment subsequent to initial manufacture when the 
standards are based upon and similar to a [FMVSS] promulgated, either 
simultaneously or previously, under chapter 301 of title 49, U.S.C.'' 
\68\ Further, section 32703(e)(2) of MAP-21 states that the ``Secretary 
may assess the feasibility, benefits, and costs with respect to the 
application of any requirement established under subsection . . . 
(b)(2) to motorcoaches manufactured before the date on which the 
requirement applies to new motorcoaches . . .'' \69\ NHTSA has issued 
this NPRM under subsection (b)(2), which directs the agency to consider 
advanced glazing standards for each motorcoach portal and consider 
other portal improvements

[[Page 27923]]

to prevent partial and complete ejection of motorcoach passengers.
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    \67\ Under sec. 101(f) of Motor Carrier Safety Improvement Act 
of 1999 (Public Law 106-159; Dec. 9, 1999).
    \68\ See 49 CFR 1.95(c). Additionally, the Federal Motor Carrier 
Safety Administration (FMCSA) is authorized to enforce the safety 
standards applicable to commercial vehicles operating in the U.S.
    \69\ See Moving Ahead for Progress in the 21st Century Act, 
Public Law 112-141, sec. 32703(e)(2).
---------------------------------------------------------------------------

    The agency has designed our approach toward adopting anti-ejection 
safety countermeasures for unbelted passengers to first force 
improvements to the rollover structural integrity of motorcoaches (roof 
strength and crush resistance) and then to pursue measures that would 
drive use of advanced glazing. This ordered approach is based on 
findings from the Martec study that the integrity of the bus structure 
has a profound impact on the effectiveness of the glazing. That is, in 
the absence of a threshold of requisite performance for bus structural 
integrity, a twisting motion of a bus in a rollover could simply pop 
out any advanced glazing used in the windows and negate the potential 
benefits of the glazing. Thus, NHTSA has tentatively decided that it 
would not be sensible to apply the requirements proposed today to buses 
that do not have sufficient structural integrity to retain the advanced 
glazing in a rollover.
    In the proposal for improved structural integrity of motorcoaches 
and other large buses, NHTSA sought comment on the retrofitting issue, 
while tentatively concluding that requiring retrofitting of existing 
buses appears impracticable. The agency discussed its tentative 
determination that, based on NHTSA's testing of the MY 1991 Prevost and 
the MY 1992 MCI buses, it appears that major structural changes to the 
vehicle's entire sidewall and roof structure would be needed for some 
existing buses to meet the proposed requirements. We discussed concerns 
that such extensive modifications may not be possible on all existing 
vehicles that would be covered by the proposed rollover structural 
integrity rule. In addition, we stated that the structural changes that 
would be entailed--assuming they could be done--would likely have 
significant cost impacts, and possibly have a substantial impact on a 
significant number of small entities (e.g., owner-operators of large 
buses used for transport).
    If NHTSA decides not to require buses to be retrofitted to meet 
rollover structural integrity requirements, then a retrofit requirement 
for advanced glazing appears unwarranted. Without measures to prevent 
the glazing from popping out in a rollover, the anti-ejection benefits 
may not be achieved. Yet, Congress was particularly interested in a 
possible retrofit requirement for advanced glazing and we would like to 
learn more about the issue. We request comments on the feasibility, 
benefits, and costs of any potential requirement to retrofit existing 
buses with advanced glazing.
    Thus, the agency seeks information on the technical and economic 
feasibility of a potential retrofit requirement. Which requirements in 
today's proposal could be appropriately applied to used buses? Is the 
agency's view reasonable that the benefits of advanced glazing might 
not be achieved if the bus's structure were not also upgraded to ensure 
the glazing stays in place in a rollover? What potential test 
procedures could the agency utilize to objectively measure compliance? 
Would it be reasonable to assess compliance with a retrofit requirement 
by means of only visually inspecting the vehicle? What lead time and 
phase-in issues should the agency consider for a potential retrofit 
requirement? What would the potential costs be?

XI. Lead Time

    If the proposed changes in this NPRM were made final, NHTSA is 
proposing a compliance date of three years after publication of a final 
rule. MAP-21 (in section 32703(e)) directs the agency to apply 
regulations prescribed in accordance with section 32703(b) ``to all 
motorcoaches manufactured more than 3 years after the date on which the 
regulation is published as a final rule.'' Based on the VRTC research, 
we believe that some manufacturers would need to redesign their 
emergency exit latch systems or adopt a design that would meet the 
proposed requirements. Also, manufacturers would also have to 
transition from double-glazed tempered/tempered windows to one that has 
at least one layer of laminated glass or advanced glazing that can meet 
all the proposed requirements. We have tentatively determined that a 3-
year lead time after publication of a final rule is appropriate as some 
design, testing, and development will be necessary to certify 
compliance to the new requirements.
    The rollover structural integrity NPRM has proposed a compliance 
date of 3 years after publication of a final rule.\70\ Similarly, we 
are proposing a compliance date of 3 years after publication of the 
final rule for this advanced glazing rulemaking. Alternatively, since 
this advanced glazing rulemaking and the structural integrity 
rulemaking are interrelated, and since the two rulemakings have been 
developed fairly close to each other in time, we are also considering 
the merits of making the compliance date of the two rulemakings the 
same.
---------------------------------------------------------------------------

    \70\ 79 FR at 46113 (August 6, 2014).
---------------------------------------------------------------------------

    We also propose that, to enable manufacturers to certify to the new 
requirements as early as possible, optional early compliance with the 
standard would be permitted.

XII. Additional MAP-21 Considerations

    MAP-21 directs that any regulation prescribed under section 
32703(b), which includes this NPRM, to take into account potential 
impacts on seating capacity, on the size/weight of motorcoaches, and to 
be based on the best available science.\71\ Further, MAP-21 directs the 
agency to consider combining the various motorcoach rulemakings 
contemplated by MAP-21 and to avoid duplicative benefits, costs, and 
countermeasures.\72\
---------------------------------------------------------------------------

    \71\ See Moving Ahead for Progress in the 21st Century Act, 
Public Law 112-141, sec. 32703(e)(1)(B).
    \72\ See id. at sec. 32706(b) and (c).
---------------------------------------------------------------------------

    NHTSA does not believe that the requirements proposed in today's 
NPRM would result in a loss of seating capacity. We estimate that the 
material and design changes resulting from this rulemaking would be a 
transition, for some side windows, from a double-glazed tempered/
tempered configuration to a single-glazed laminated configuration, and 
relatively simple changes to latch designs that would enable latches to 
stay closed when subjected to a nearby impact. Design changes would 
also be made to latches so that they do not protrude more than 25 mm (1 
inch) into the opening of an emergency exit when the window is open. We 
do not expect these material and design changes to result in a loss of 
seating capacity. The agency requests comment on this issue.
    There could be potential impacts from this rulemaking on the weight 
of motorcoaches, but we believe there would be a potential weight 
decrease (and thus a potential cost savings due to decreased fuel 
consumption). As discussed in the next section, the transition from a 
double-glazed tempered/tempered configuration to a single-glazed 
laminated configuration could save an estimated 23-33 pounds per window 
(276-396 pounds per bus), thereby increasing the overall fuel economy 
during the lifetime of these buses. In the accompanying PRE, we have 
attempted to quantify and account for this potential cost savings in 
our cost-benefit analysis of the rule. Comments are requested on this 
issue.
    NHTSA has considered the best available science in developing 
today's NPRM. We discuss in the section on ``Research,'' supra, the 
studies on which this NPRM is based. In that section, we discuss the 
findings from the joint NHTSA and Transport Canada

[[Page 27924]]

motorcoach program (the Martec Study), NHTSA's motorcoach side glazing 
retention research, and NHTSA's large bus rollover structural integrity 
research program. We discuss how we used those findings to develop this 
NPRM.
    Ejections are a large part of the safety problem in crashes of 
motorcoaches and other large buses, particularly in rollovers. To 
mitigate ejections, NHTSA has adopted a final rule to require passenger 
seat belts, and has proposed today's NPRM on advanced glazing to reduce 
full ejections of unbelted passengers and partial ejections of belted 
and unbelted occupants. Consistent with MAP-21, the agency has taken a 
holistic approach toward adopting anti-ejection safety countermeasures 
for unbelted passengers, by first seeking improvements to the rollover 
structural integrity of motorcoaches (roof strength and crush 
resistance) and then pursuing measures that would drive use of advanced 
glazing, while making sure to avoid duplicative benefits, costs and 
countermeasures. NHTSA tentatively believes that the proposed 
structural integrity test (based on ECE R.66) can be used not only to 
evaluate the structural integrity of a large bus in maintaining the 
occupant compartment but also to evaluate the strength of its 
structural integrity in supporting side window glazing retention. Thus, 
the agency has fashioned the two rulemakings to complement each other 
to achieve portal improvements in preventing partial and complete 
ejection of motorcoach passengers.
    NHTSA believes it avoided the duplication of benefits, costs, and 
countermeasures of other potential NHTSA rules being considered 
pursuant to MAP-21.\73\ There is no regulation that adequately 
addresses window retention or ejection mitigation through glazing under 
dynamic occupant loading in rollovers. The proposed FMVSS No. 227 
requirements for bus structural integrity would require that windows 
(on the non-roll side) remain intact in their framing during the 
quarter turn, do not open up during the quarter turn, and have no 
openings large enough to admit passage of a 102 mm (4 inch) diameter 
sphere after the quarter turn. However, the forces that would be 
experienced by the windows in the proposed FMVSS No. 227 test are 
purely inertial and are not representative of any direct occupant 
loading from within the bus.
---------------------------------------------------------------------------

    \73\ As we further discuss in the next section and in the PRE 
for today's NPRM, we have adjusted the target population based on 
the projected benefits that would be attributable to other NHTSA 
rulemakings for the subject buses. Separately, we also considered 
whether there have been any recent FMCSA actions which might affect 
the projected target population and we have tentatively concluded 
that they would not. FMCSA has issued several final rules directed 
at bus and truck safety, including Medical Certificate Requirements 
as Part of the Commercial Driver's License in 2008, Drivers of 
Commercial Vehicles: Restricting the Use of Cellular Phones in 2011, 
Hours of Service in 2011, and National Registry of Certified Medical 
Examiners in 2012. In addition, FMCSA has had several recent 
enforcement efforts to improve bus safety, including several 
nationwide ``Strike Force'' enforcement events. NHTSA believes that 
the benefits estimated in this NPRM would not overlap with the 
benefits attained by FMCSA actions associated with bus safety.
---------------------------------------------------------------------------

    Our seat belt requirement mitigates the risk of ejection of 
passengers on motorcoaches and other large buses, but seat belt usage 
rates by occupants of these vehicles are uncertain. In addition, even 
if occupants are belted, there are risks associated with partial 
ejections. Advanced glazing in window openings and improved mountings 
would mitigate the risk of ejection of occupants who may not be 
restrained at the time of the crash, and would help protect against 
partial ejections of both restrained and unrestrained occupants. 
Today's NPRM proposes requirements that would result in portal 
improvements by way of advanced glazing, consistent with the goals of 
the Motorcoach Safety Enhancement Act of MAP-21.

XIII. Overview of Benefits and Costs

    A detailed discussion of the benefits and costs estimates may be 
found in the PRE for this NPRM.\74\
---------------------------------------------------------------------------

    \74\ The PRE discusses issues relating to the potential costs, 
benefits and other impacts of this regulatory action. The PRE is 
available in the docket for this NPRM and may be obtained by 
downloading it or by contacting Docket Management at the address or 
telephone number provided at the beginning of this document.
---------------------------------------------------------------------------

Target Population

    Figure 4 below shows the annual fatal target population in OTRB and 
certain large bus rollovers and estimated lives saved from various bus 
rulemakings. The overall fatal target population in OTRB and certain 
large bus rollovers is 14.7 fatalities annually. ESC equipment on the 
subject buses reduces the chance of a rollover, and is estimated to 
prevent 1.47 fatalities annually. The resulting overall fatal target 
population in the subject OTRBs and other buses, with ESC, is 13.23 
fatalities annually.
    In the 2013 seat belt final rule and the structural integrity NPRM, 
NHTSA estimated that seat belt use rates would range from 15 percent to 
84 percent and that the effectiveness of seat belts in rollover crashes 
is 77 percent. Therefore, the seat belt final rule would save 1.45 
lives at 15 percent belt use rate and 8.1 lives at 84 percent belt use 
rate and thereby reducing the fatal target population in the subject 
buses to 11.78 and 5.13 fatalities annually, respectively. For the 15 
percent seat belt use rate, the fatal population is broken down to 0.78 
restrained occupant fatalities and 11.0 unrestrained occupant 
fatalities. Likewise, for the 84 percent seat belt use rate, the fatal 
population is broken down to 2.77 restrained occupant fatalities and 
2.36 unrestrained occupant fatalities. Each restrained and unrestrained 
population is further broken down to subpopulations of ejected and non-
ejected fatalities (see Figure 4).

[[Page 27925]]

[GRAPHIC] [TIFF OMITTED] TP06MY16.040

    The agency estimates in the rollover structural integrity PRE a 71 
percent effectiveness of ejection mitigation in preventing fatalities. 
The rollover structural integrity PRE further estimates that, since the 
enhanced rollover structural integrity test procedure does not include 
a condition simulating occupant loading, NHTSA would estimate a 
midpoint effectiveness of 35 percent for unbelted ejected fatalities. 
That is, that effectiveness would result from just the windows being 
retained in their surrounding structures due to the rollover structural 
integrity requirements. Due to today's proposed requirements, advanced 
glazing and secure bonding techniques would be used that withstand 
occupant loading. Accordingly, we estimate that the remainder of the 
overall 71 percent effectiveness for the ejected fatal population is 
accounted for with today's NPRM (36 percent effectiveness). Based on 
the various rollover tests on buses performed by the agency, we 
determined that advanced glazing is effective in one and two quarter 
turn rollovers. Evaluating the various bus rollover crashes that have 
occurred in the real world, we estimated that 58 percent of large bus 
rollover crashes are one and two quarter turns. Therefore, the overall 
effectiveness of advanced glazing for all large bus rollover crashes is 
approximately 21 percent (58 percent of 36 percent effectiveness).
    The target population (unrestrained ejected occupants in rollover 
crashes) estimated for this proposal, after discounting the benefits 
from the other initiatives applicable to the same group of buses (ESC, 
seat belts, rollover structural integrity) is 7.37 fatalities at the 15 
percent seat belt use rate and 1.58 fatalities at the 84 percent seat 
belt use rate.

Benefits

    Applying a 21 percent effectiveness of enhanced window retention, 
we estimate this proposal to save 1.54 (= 7.37 x 0.209) lives annually 
at the 15 percent seat belt use rate and 0.33 (= 1.58 x 0.209) lives 
annually at the 84 percent seat belt use rate.
    Assuming that the proposed glazing and window retention 
requirements are only effective in one and two quarter turn bus 
rollover events in preventing serious and critical injuries to bus 
passengers, we estimated that 0.4 and 0.08 serious to critical injuries 
would be prevented for a 15 percent and 84 percent belt use rate, 
respectively. Therefore the equivalent lives saved by the proposed 
requirements are 1.6 for 15 percent belt use rate and 0.34 for 84 
percent belt use rate.
    We believe that our benefits estimate is conservative. We did not 
consider benefits that could result in crash modes other than 
rollovers, although advanced glazing could be beneficial in those 
crashes as well. In addition, potential benefits could also accrue from 
the requirement that would limit how far emergency exit latch 
protrusions may extend into the emergency exit opening of the window 
when the window is opened for emergency egress. Comments are requested 
on how NHTSA could estimate or account for these potential benefits.
Costs
    We estimated the cost of this rulemaking by comparing the cost of 
glazing made from tempered glass (which would not meet the proposed 
advanced glazing requirements) to glazing comprised of laminated glass 
(which would meet the proposed requirements). We estimate that a fully 
framed and assembled double-glazed tempered/tempered window 
(approximately 25 square feet) costs $340. We estimate that a fully 
framed and assembled single-glazed laminated window (approximately 25 
square feet) costs $353.75. Thus, the incremental cost of choosing a 
single-glazed laminated window over a double-glazed tempered/tempered 
window is $13.75 per window ($0.55 per square foot).
    Our cost estimate for this rulemaking also includes changes that 
would have to be made to window latch systems. NHTSA found \75\ that 
none of the production latches the agency studied could meet the 
proposed dynamic

[[Page 27926]]

impact test requirement. However, a simple washer screwed onto the top 
of the existing MCI E/J-series striker post proved to be a simple and 
inexpensive countermeasure that enabled the latches to meet the 
proposed requirements.\76\ The cost of each washer was $0.05.
---------------------------------------------------------------------------

    \75\ ``Motorcoach Side Glazing Retention Research,'' November 
2013, supra.
    \76\ It could be that a simple washer countermeasure only worked 
for the MCI latch design, and hence other bus models may need to use 
other designs to achieve compliance. However, other manufacturers 
could adopt a system similar to the MCI latch system, so costs are 
not likely to be significantly greater to redesign the latches.
---------------------------------------------------------------------------

    We estimate that there are 2,200 new over-the-road and subject 
large buses manufactured annually. Assuming an OTRB or large bus has 6 
large windows on each side and that all of them are emergency exits 
with latch mechanisms similar to that of the MCI E/J-series, the total 
incremental cost of redesigning the bus (from a double-glazed tempered/
tempered window to a single-glazed laminated window) to meet the 
proposed requirements is $165.60 (= $13.75 x 12 + $0.05 x 12).
    On the other hand, we believe that there are a substantial number 
of buses that already meet the proposed advanced glazing requirements. 
We estimated that 47.7 percent of large buses covered by this proposal 
are already equipped with laminate glazing. Assuming that 47.7 percent 
of the 2,200 new buses covered by the proposal are MCI designs that 
already use laminated glazing, the buses would only need the necessary 
latch countermeasures to meet the proposed requirements. The remaining 
60 percent of the new annual covered bus production would have to incur 
the incremental cost of having to convert to a single-glazed laminated 
configuration, at a minimum, as well as provide latch countermeasures, 
in order to meet the proposed requirements of this rulemaking. Assuming 
these factors, the total annual incremental cost for new buses covered 
under this proposal is estimated to be $191,169 (= 2,200 x 0.477 x 
$0.60 + 2,200 x 0.523 x $165.60).
    We note that there could be cost savings resulting from this 
rulemaking due to weight implications. The transition from a double-
glazed tempered/tempered configuration to a single-glazed laminated 
configuration could save an estimated 23-33 pounds per window (276-396 
pounds per bus), thereby increasing the overall fuel economy during the 
lifetime of these buses. We estimate that the fuel savings ($2.18 
million to $2.9 million) exceed the material costs of $0.19 million for 
the proposal. Comments are requested on this issue.
    The proposed test is estimated to cost $8,700 per bus model, 
including the cost of the replacement windows and labor.\77\ Testing 
cost is not explicitly included in the cost analysis since it is 
considered research and development or overhead for the manufacturers, 
which is already included in the 1.5 markup factor from variable costs 
to retail price equivalent.
---------------------------------------------------------------------------

    \77\ For a bus with emergency (with latch) and non-emergency 
(without latch) windows, the cost of testing both types of windows 
is as follows: For an approximate cost of single-glazed laminate 
window of $1,320, cost of 6 replacement windows and installation 
material is $8,100. Three technicians with $20/hr wage for one day 
would be $480 and with 25 percent overhead, total labor cost is 
$600. Therefore the total cost of testing window retention for a bus 
is $8,700 (= $8,100 + $600).
---------------------------------------------------------------------------

    The benefits and costs of this proposed rule are summarized in the 
following tables 7, 8, and 9.

                     Table 7--Estimated Annual Costs
                             [2013 dollars]
------------------------------------------------------------------------
 
------------------------------------------------------------------------
                             Potential costs
------------------------------------------------------------------------
Material Costs Per Vehicle................  $87
Material Costs, Total New Fleet...........  $0.19 Million
------------------------------------------------------------------------

                   Table 8--Estimated Annual Benefits
                  [Undiscounted equivalent lives saved]
------------------------------------------------------------------------
 
------------------------------------------------------------------------
15 percent belt usage......................................         1.6
84 percent belt usage......................................         0.34
------------------------------------------------------------------------

                        Table 9--Annualized Net Benefits in Millions (M) of 2013 Dollars
----------------------------------------------------------------------------------------------------------------
                  Discount rate (%)                        Benefits            Net costs         Net benefits
----------------------------------------------------------------------------------------------------------------
3...................................................        $13.22-$2.82       ($4.30-$3.05)        $17.52-$5.87
7...................................................         $9.95-$2.12       ($3.20-$2.25)        $13.15-$4.37
----------------------------------------------------------------------------------------------------------------

    The Value of a Statistical Life (VSL) is $9.2M in 2013 dollars. The 
estimated net benefit for this rule is $5.87 million to $17.52 million 
(with a 3 percent discount rate) and $4.37 million to $13.15 million 
(with a 7 percent discount rate).

XIV. Regulatory Notices and Analyses

Executive Order 12866, Executive Order 13563, and DOT Regulatory 
Policies and Procedures

    This rulemaking document was not reviewed by the Office of 
Management and Budget under E.O. 12866. It is not considered to be 
significant under E.O. 12866 or the Department's Regulatory Policies 
and Procedures (44 FR 11034; February 26, 1979). NHTSA has prepared a 
PRE for this NPRM.
    This NPRM proposes to adopt a standard that would drive the 
installation of advanced glazing in the subject buses. NHTSA would 
adopt an impactor test of glazing material. In the tests, a 26 kg (57 
lb) impactor would be propelled from inside a test vehicle toward the 
window glazing. The impactor and impact speed in these proposed tests 
simulate the loading from an average size adult male impacting a window 
on the opposite side of a large bus in a rollover. Performance 
requirements would apply to side and rear windows and glass panels on 
roof that ensure that glazing is securely bonded to window frames, that 
advanced glazing retains occupants within the structural sidewall of 
the bus even when damaged, and that emergency exit latches remain 
closed when impacted. NHTSA also proposes to limit how far emergency 
exit latch protrusions may extend into the emergency exit opening of 
the window when the window is opened for emergency egress.
    Beyond the benefits attributable to the rule on seat belts and ESC 
for this same group of vehicles and a possible rule on bus structural 
integrity, we estimate that requiring new large buses of these types to 
meet the proposed performance criteria would save 1.54 lives annually 
at a 15 percent seat belt use rate and 0.33 lives annually at a 84 
percent seat belt use rate. The total annual incremental material cost 
for new buses covered under this proposal is estimated to be 
approximately $0.19 million (for the entire new fleet) and fuel savings 
due to reduced weight of single glazed laminate over double glazed 
tempered window configuration is $2.18 million to $2.9 million. The 
estimated net benefit for this rule is $5.87 million to $17.52 million 
with a 3 percent discount rate and $4.37 million to

[[Page 27927]]

$13.15 million with a 7 percent discount rate. The benefits, costs, and 
other impacts of this rulemaking are summarized in the previous section 
of this preamble and fully discussed in the PRE.

Executive Order 13609: Promoting International Regulatory Cooperation

    The policy statement in section 1 of Executive Order 13609 
provides, in part:

The regulatory approaches taken by foreign governments may differ 
from those taken by U.S. regulatory agencies to address similar 
issues. In some cases, the differences between the regulatory 
approaches of U.S. agencies and those of their foreign counterparts 
might not be necessary and might impair the ability of American 
businesses to export and compete internationally. In meeting shared 
challenges involving health, safety, labor, security, environmental, 
and other issues, international regulatory cooperation can identify 
approaches that are at least as protective as those that are or 
would be adopted in the absence of such cooperation. International 
regulatory cooperation can also reduce, eliminate, or prevent 
unnecessary differences in regulatory requirements.

    As mentioned in the body of this preamble, the agency has developed 
this NPRM by building on the changes to motorcoach structure that 
manufacturers would implement in response to the agency's August 6, 
2014 structural integrity NPRM (79 FR 46090). NHTSA based that NPRM on 
the ECE R.66 complete vehicle rollover test. By designing NHTSA's 
approach to anti-ejection safety countermeasures to incorporate ECE 
R.66, NHTSA would reduce unnecessary differences in regulatory 
requirements between the U.S. and its trading partners. A bus that 
meets ECE R.66 would have the bus structure needed to ensure that 
glazing is retained in bus portals in a rollover, and today's NPRM 
would ensure that windows are only made of advanced glazing.

Regulatory Flexibility Act

    Pursuant to the Regulatory Flexibility Act (5 U.S.C. 601 et seq., 
as amended by the Small Business Regulatory Enforcement Fairness Act 
(SBREFA) of 1996), whenever an agency is required to publish a notice 
of rulemaking for any proposed or final rule, it must prepare and make 
available for public comment a regulatory flexibility analysis that 
describes the effect of the rule on small entities (i.e., small 
businesses, small organizations, and small governmental jurisdictions). 
The Small Business Administration's regulations at 13 CFR part 121 
define a small business, in part, as a business entity ``which operates 
primarily within the United States.'' (13 CFR 121.105(a)). No 
regulatory flexibility analysis is required if the head of an agency 
certifies that the rule will not have a significant economic impact on 
a substantial number of small entities. The SBREFA amended the 
Regulatory Flexibility Act to require Federal agencies to provide a 
statement of the factual basis for certifying that a rule will not have 
a significant economic impact on a substantial number of small 
entities.
    NHTSA has considered the effects of this rulemaking action under 
the Regulatory Flexibility Act. According to 13 CFR 121.201, the Small 
Business Administration's size standards regulations used to define 
small business concerns, manufacturers of the vehicles covered by this 
proposed rule would fall under North American Industry Classification 
System (NAICS) No. 336111, Automobile Manufacturing, which has a size 
standard of 1,000 employees or fewer. NHTSA estimates that there are 26 
manufacturers of these types of vehicles in the United States 
(including manufacturers of motorcoaches, cutaway buses, second-stage 
motorcoaches, and other types of large buses covered by this proposal). 
Using the size standard of 1,000 employees or fewer, we estimate that 
approximately 10 of these 26 manufacturers would be considered small 
businesses.
    The agency does not believe that this proposed rule would have a 
significant economic impact on those small entities. First, the agency 
estimates that the incremental costs to each vehicle that currently 
does not comply with the proposed requirements would be approximately 
$165 per unit to meet the proposed rule. This incremental cost would 
not constitute a significant impact given that the average cost of the 
vehicles covered by this proposed rule ranges from $200,000 to 
$400,000. Further, these incremental costs, which are very small 
compared to the overall cost of the vehicle, can ultimately be passed 
on to the purchaser and user.
    In addition, the agency believes that certifying compliance with 
the proposed rule would not have a significant impact on the 
manufacturers. Small manufacturers have various options available that 
they may use in certifying compliance with the proposed standard. 
Manufacturers are not required to use NHTSA's test as the basis for 
their certification. While the agency's test defined in the proposed 
regulatory test would be an objective test capable of determining which 
vehicles meet the minimum requirements, manufacturers can use other 
methods in certifying the compliance of their own vehicles.
    For instance, a manufacturer could obtain advanced glazing windows 
from a glazing supplier and test the glazing on body sections of the 
vehicle. NHTSA used this approach in its motorcoach side glazing 
retention research program. The manufacturer could ``section'' the 
vehicle or otherwise obtain a body section representative of the 
vehicle, or test the glazing on test frames. It could base its 
certification on these tests, without testing a full vehicle.
    Unlike NHTSA, manufacturers certifying compliance of their own 
vehicles have more detailed information regarding their own vehicles 
and can use reasonable engineering analyses to determine whether their 
vehicles will comply with the proposed requirements. We believe that a 
small manufacturer would be closely familiar with its own vehicle 
design and would be able to utilize modeling and relevant analyses on a 
vehicle-by-vehicle basis to reasonably predict whether its design will 
meet the requirements of today's proposed rule.
    We also note that the product cycle of the covered buses is 
significantly longer than other vehicle types. With a longer product 
cycle, we believe that the costs of certification for manufacturers 
would be further reduced as the costs of conducting compliance testing 
and the relevant analyses could be spread over a significantly longer 
period of time.
    Finally, we note that the requirements in today's proposed rule may 
affect the operators of the buses that are the subject of today's 
NPRM--some of which may be small businesses--but only indirectly as 
purchasers of these vehicles. As mentioned above, we anticipate that 
the impact on these businesses will not be significant because the 
expected price increase of the vehicles (those that do not comply with 
the proposed requirements) used by these businesses is small ($165 for 
each vehicle valued between $200,000 and $400,000). Further, we 
anticipate that fuel costs for these businesses may decrease due to 
today's proposed amendments.
    For the aforementioned reasons, I hereby certify that if made 
final, this proposed rule would not have a significant economic impact 
on a substantial number of small entities.
    With regard to a retrofit requirement applying to a population of 
on-road vehicles, the agency has tentatively determined that requiring 
retrofitting of existing vehicles would not be practical. Comments are 
requested on this issue. An estimated 78.8 percent of the 3,137 
motorcoach carriers (according to the

[[Page 27928]]

2008 Motorcoach Census) in the United States in 2007 (i.e. about 2,470 
carriers) have less than 10 motorcoaches in their fleet. Further, these 
companies have an average of three vehicles and eleven employees.\78\ 
NHTSA tentatively believes that to include retrofit requirements would 
be a substantial burden on these small carriers.
---------------------------------------------------------------------------

    \78\ While the vehicles included in the motorcoach census are 
not exactly the same as the vehicles covered in today's proposal, we 
believe the industry's Motorcoach Census offers a reasonable 
estimate of the proportion of bus carrier companies that would be 
affected as owners/operators of the buses covered in today's NPRM.
---------------------------------------------------------------------------

    Furthermore, we believe that it would not make sense to require 
retrofitting of windows with advanced glazing if the underlying 
structure of the buses were not reinforced to prevent the glazing from 
popping out in a rollover. It may not be structurally viable for many 
of these used large buses to be retrofitted. In the August 6, 2014 
structural integrity NPRM, NHTSA tentatively decided not to include 
retrofit requirements but requested comments on the issue. In today's 
NPRM, we also seek comment as to whether the advanced glazing 
requirements should be applied to used buses.

Executive Order 13132 (Federalism)

    NHTSA has examined today's proposed rule pursuant to Executive 
Order 13132 (64 FR 43255; Aug. 10, 1999) and concluded that no 
additional consultation with States, local governments, or their 
representatives is mandated beyond the rulemaking process. The agency 
has concluded that the proposed rule does not have sufficient 
federalism implications to warrant consultation with State and local 
officials or the preparation of a federalism summary impact statement. 
The proposed rule 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 rules can have preemptive effect in 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 by 
Congress that preempts any non-identical State legislative and 
administrative law address the same aspect of performance.
    The express preemption provision described above is subject to a 
savings clause under which ``[c]ompliance with a motor vehicle safety 
standard prescribed under this chapter does not exempt a person from 
liability at common law.'' 49 U.S.C. 30103(e) Pursuant to this 
provision, State common law tort causes of action against motor vehicle 
manufacturers that might otherwise be preempted by the express 
preemption provision are generally preserved. However, the Supreme 
Court has recognized the possibility, in some instances, of implied 
preemption of State common law tort causes of action by virtue of 
NHTSA's rules--even if not expressly preempted.
    This second way that NHTSA rules can preempt is dependent upon the 
existence of an actual conflict between an FMVSS and the higher 
standard that would effectively be imposed on motor vehicle 
manufacturers if someone obtained a State common law tort judgment 
against the manufacturer--notwithstanding the manufacturer's compliance 
with the NHTSA standard. Because most NHTSA standards established by an 
FMVSS are minimum standards, a State common law tort cause of action 
that seeks to impose a higher standard on motor vehicle manufacturers 
will generally not be preempted. However, if and when such a conflict 
does exist--for example, when the standard at issue is both a minimum 
and a maximum standard--the State common law tort cause of action is 
impliedly preempted. See Geier v. American Honda Motor Co., 529 U.S. 
861 (2000).
    Pursuant to Executive Order 13132, NHTSA has considered whether 
this proposed rule could or should preempt State common law causes of 
action. The agency's ability to announce its conclusion regarding the 
preemptive effect of one of its rules reduces the likelihood that 
preemption will be an issue in any subsequent tort litigation.
    To this end, the agency has examined the nature (e.g., the language 
and structure of the regulatory text) and objectives of today's 
proposed rule and does not foresee any potential State requirements 
that might conflict with it. NHTSA does not intend that this proposed 
rule preempt state tort law that would effectively impose a higher 
standard on motor vehicle manufacturers than that established by 
today's rule. Establishment of a higher standard by means of State tort 
law would not conflict with the standards proposed in this NPRM. 
Without any conflict, there could not be any implied preemption of a 
State common law tort cause of action.

National Environmental Policy Act

    NHTSA has analyzed this NPRM for the purposes of the National 
Environmental Policy Act. The agency has determined that implementation 
of this action would not have any significant impact on the quality of 
the human environment.

Paperwork Reduction Act

    Under the procedures established by the Paperwork Reduction Act of 
1995, 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. This rulemaking would not establish any new 
information collection requirements.

National Technology Transfer and Advancement Act

    Under the National Technology Transfer and Advancement Act of 1995 
(NTTAA) (Pub. L. 104-113), ``all Federal agencies and departments shall 
use technical standards that are developed or adopted by voluntary 
consensus standards bodies, using such technical standards as a means 
to carry out policy objectives or activities determined by the agencies 
and departments.'' 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 (SAE). The NTTAA directs this agency to provide Congress, 
through OMB, explanations when the agency decides not to use available 
and applicable voluntary consensus standards.
    NHTSA is not aware of any voluntary standards that exist regarding 
advanced glazing as an anti-ejection safety countermeasure for large 
buses. However, this NPRM proposes to adopt a performance test that is 
based on the test procedures developed in the joint NHTSA and Transport 
Canada research program (the Martec study). NHTSA's consideration of 
this procedure accords with the principles of NTTAA, in that NHTSA is 
considering an existing procedure and has not had to expend additional 
agency resources studying the same safety need addressed by the Martec 
study.

Executive Order 12988

    With respect to the review of the promulgation of a new regulation,

[[Page 27929]]

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 (6) 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 issue of 
preemption is discussed above in connection with E.O. 13132. 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.

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 $135 million annually 
(adjusted for inflation to 2009 dollars with base year of 1995). This 
NPRM would not result in expenditures by State, local or tribal 
governments, in the aggregate, or by the private sector in excess of 
$135 million annually.

Plain Language

    Executive Order 12866 and E.O. 13563 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 proposal.

Regulation 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 65, Number 70; Pages 19477-78).

XV. 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.
    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.

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 
business information, to the Chief Counsel, NHTSA, at the address given 
above under FOR FURTHER INFORMATION CONTACT. In addition, you should 
submit a copy, from which you have deleted the claimed confidential 
business information, to the docket 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 received before the close of business 
on the comment closing date indicated above under DATES. To the extent 
possible, we will also consider comments that the docket receives after 
that date. If the docket 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 the docket 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. 
You can arrange with the docket to be notified when others file 
comments in the docket. See www.regulations.gov for more information.

[[Page 27930]]

List of Subjects in 49 CFR Part 571

    Imports, Motor vehicles, Motor vehicle safety.

    In consideration of the foregoing, NHTSA proposes to amend 49 CFR 
part 571 as follows:

PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS

0
1. The authority citation for part 571 continues to read as follows:

    Authority:  49 U.S.C. 322, 30111, 30115, 30117, and 30166; 
delegation of authority at 49 CFR 1.95.

0
2. Section 571.217 is amended by removing the definition of ``Daylight 
opening'' in S4, adding a sentence to the end of S5.4.1, revising 
S5.4.2.2, and adding Figure 4 to read as follows:

Sec.  571.217  Standard No. 217; Bus emergency exits and window 
retention and release.

* * * * *
    S5.4.1 * * * The emergency exit latches, or other related release 
mechanisms, shall not protrude more than 25 millimeters into the 
opening of the emergency exit when the window is in the open position 
as described in this paragraph.
* * * * *
    S5.4.2.2 School buses with a GVWR of 10,000 pounds or less. A 
school bus with a GVWR of 10,000 pounds or less shall conform to all 
the provisions of S5.4.2.1 of this section, except that the 
parallelepiped dimension for the opening of the rear emergency door or 
doors shall be 45 inches high, 22 inches wide, and six inches deep. The 
emergency exit latches, or other related release mechanisms, shall not 
protrude more than (1 inch) into the opening of the emergency exit when 
the window is in the open position as described in S5.4.1 of this 
section.
[GRAPHIC] [TIFF OMITTED] TP06MY16.041

[[Page 27931]]

0
3. Section 571.217a is added to read as follows:

Sec.  571.217a  Standard No. 217a; Anti-ejection glazing for bus 
portals.

    S1. Scope. This standard establishes requirements to improve side, 
rear, and roof bus portals by way of glazing that is highly resistant 
to partial or complete occupant ejection in all types of crashes.
    S2. Purpose. The purpose of this standard is to reduce death and 
injuries resulting from complete and partial ejections of bus occupants 
through side, rear, and roof portals during rollovers and other 
crashes.
    S3. Application.
    (a) Subject to S3(b) of this section, this standard applies to:
    (1) Over-the-road buses, and
    (2) Buses, other than over-the-road buses, that have a gross 
vehicle weight rating (GVWR) greater than 11,793 kilograms.
    (b) This standard does not apply to school buses, transit buses, 
prison buses, and perimeter-seating buses.
    S4. Definitions.
    Daylight opening means, for openings on the side of the vehicles 
(other than a door opening), the locus of all points where a horizontal 
line, perpendicular to the vehicle longitudinal centerline, is tangent 
to the periphery of the opening. For openings on the rear of the 
vehicle (other than a door opening), daylight opening means the locus 
of all points where a horizontal line, parallel to the vehicle 
longitudinal centerline, is tangent to the periphery of the opening. 
For openings on the roof of the vehicle, daylight opening means the 
locus of all points where a vertical line is tangent to the periphery 
of the opening. The periphery includes surfaces 100 millimeters (mm) 
inboard of the inside surface of the window glazing and 25 mm outboard 
of the outside surface of the window glazing. The periphery excludes 
the following: Any flexible gasket material or weather stripping used 
to create a waterproof seal between the glazing and the vehicle 
interior; grab handles used to facilitate occupant egress and ingress; 
and any part of a seat.
    Over-the-road bus means a bus characterized by an elevated 
passenger deck located over a baggage compartment.
    Perimeter-seating bus means a bus with 7 or fewer designated 
seating positions rearward of the driver's seating position that are 
forward-facing or can convert to forward-facing without the use of 
tools and is not an over-the-road bus.
    Portal means an opening that could, in the event of a crash 
involving the vehicle, permit the partial or complete ejection of an 
occupant from the vehicle, including a young child.
    Prison bus means a bus manufactured for the purpose of transporting 
persons subject to involuntary restraint or confinement and has design 
features consistent with that purpose.
    Stop-request system means a vehicle-integrated system for passenger 
use to signal to a vehicle operator that they are requesting a stop.
    Transit bus means a bus that is equipped with a stop-request system 
sold for public transportation provided by, or on behalf of, a State or 
local government and that is not an over-the-road bus.
    S5 Requirements. When tested according to the procedures specified 
in S6 of this section and under the conditions specified in S7 of this 
section, each bus shall meet the following requirements specified in 
this section. The requirements of S5 of this section do not apply to 
portals other than side, rear, and roof portals, and do not apply to a 
side, rear, or roof portal whose minimum surface dimension measured 
through the center of its area is less than 279 millimeters.
    S5.1 Edge impact.
    (a) When the ejection impactor described in S8 of this section 
contacts the target location specified in S6.1.1 of this section of 
each side, rear, or roof daylight opening of a vehicle at 21.6 km/h, no 
portion of the window (excluding glazing shards) may pass the ejection 
reference plane defined under the procedures of S6 of this section.
    (b) Each piece of window glazing and each surrounding window frame 
shall be retained by its surrounding structure in a manner that 
prevents the formation of any opening large enough to admit the passage 
of a 102 millimeter diameter sphere when a force of no more than 22 
Newtons is applied with the sphere at any vector in a direction from 
the interior to the exterior of the vehicle.
    S5.2 Center impact.
    (a) When the ejection impactor described in S8 of this section 
contacts the target location specified in S6.1.2 of this section of 
each side, rear, or roof daylight opening of a vehicle at 21.6 
kilometers per hour, no portion of the window (excluding glazing 
shards) may pass the ejection reference plane defined under the 
procedures of S6 of this section.
    (b) Each piece of window glazing and each surrounding window frame 
shall be retained by its surrounding structure in a manner that 
prevents the formation of any opening large enough to admit the passage 
of a 102 millimeter diameter sphere under a force, including the weight 
of the sphere, of up to 22 Newtons.
    S5.3 Center impact to pre-broken glazing.
    (a) When the ejection impactor described in S8 of this section 
contacts the target location specified in S6.1.3 of this section of 
each side, rear, or roof daylight opening of a vehicle at 21.6 
kilometers per hour, no portion of the impactor may displace more than 
175 mm past where the surface of the glazing had been in an unbroken 
condition.
    (b) Each piece of window glazing and each surrounding window frame 
shall be retained by its surrounding structure in a manner that 
prevents the formation of any opening large enough to admit the passage 
of a 102 millimeter diameter sphere when a force of no more than 22 
Newtons is applied with the sphere at any vector in a direction from 
the interior to the exterior of the vehicle.
    S5.4 After the impact described in S5.1, S5.2, and S5.3 of this 
section, each emergency exit provided in accordance with Standard No. 
217 (Sec.  571.217) shall be capable of releasing and opening according 
to the requirements specified in that standard.
    S6. Test procedures.
    S6.1 Target locations.
    S6.1.1 Edge impact. Position the impactor face on the glazing 
adjacent to a latch or discrete attachment point such that, when viewed 
perpendicular to the glazing surface, the center of the impactor face 
plate is as close as practicable to the center of the latch or discrete 
attachment point with the impactor face plate either horizontal or 
vertical, whichever orientation provides the shortest distance between 
the two centers, while maintaining at least a 25 millimeter distance 
between the impactor face plate edge and the window frame. ``Window 
frame'' includes latches, handles, attachments, and any solid 
structures other than the glazing material or flexible gaskets. If the 
window does not have any latches or discrete attachment points (e.g., 
it is fully rubber bonded or glued), position the impactor directly 
above the center of the lower window edge, with the impactor face plate 
either horizontal or vertical, whichever orientation provides the 
shortest distance between the two centers, with the bottom edge of the 
impactor face plate 25 millimeter above the daylight opening periphery 
when viewed perpendicular to the glazing surface.
    S6.1.2 Center impact. Position the center of the impactor face, 
with the long axis of the impactor face plate either vertical or 
horizontal, at the

[[Page 27932]]

center of the daylight opening area of the window with the glazing 
intact.
    S6.1.3 Center impact to pre-broken glazing. Position the center of 
the impactor face, with the long axis of the impactor face plate either 
vertical or horizontal, at the center of the daylight opening area of 
the window with the glazing pre-broken following the procedure in S6.2 
of this section.
    S6.2 Window glazing pre-breaking procedure.
    S6.2.1 Breakage pattern. Locate the geometric center of the 
daylight opening. Mark the surface of the window glazing in a 
horizontal and vertical grid of points separated by 75  2 
millimeters with one point coincident within 2 millimeters 
of the geometric center of the daylight opening.
    (a) If the window is a single-pane unit, then both the occupant 
space interior and outside exterior surfaces of the glass pane are 
marked with the 75 millimeter grid pre-break pattern. The patterns are 
offset diagonally from one another (the points on one surface of the 
glass pane are offset 35 millimeters horizontally and 35 millimeters 
vertically from the points on the contralateral surface of the glass 
pane).
    (b) If the window is an insulated-unit or double-glazed window, 
then both the occupant space side of the interior pane and the outside 
of the exterior pane are marked with the 75 millimeter grid pre-break 
pattern.
    (1) If one of the glass panes is constructed of tempered or 
toughened glass, the insulated surface of the remaining glass pane 
(within the air gap) are marked with the 75 millimeter grid pre-break 
pattern. The patterns are offset diagonally from its contralateral 
surface.
    (2) If neither pane is tempered glass, then both the occupant space 
side of the interior pane and the outside of the exterior pane are 
marked with the 75 millimeter grid pre-break pattern. The patterns are 
not diagonally offset from one another. The insulated surfaces of the 
glass panes (within the air gap) are not pre-broken.
    S6.2.2 Breakage method.
    (a) Start with the inside surface of the window and forward-most, 
lowest mark made as specified in S6.2.1 of this section. Use an 
electric staple gun without any staples to make a hole in the glazing. 
The staple gun applies a line load of about 12 to 14 millimeters on the 
glazing.
    (b) Use a 100  10 millimeters x 100  10 
millimeters piece of rigid material as a reaction surface on the 
opposite side of the glazing to prevent to the extent possible the 
window surface from deforming by more than 10 millimeters when pressure 
is being applied by the staple gun.
    (c) Continue making holes by moving rearward in the grid until the 
end of a row is reached. Then move to the forward-most mark on the next 
higher row and make a hole. Continue in this pattern until all the 
holes on the inside surface of the glazing are made.
    (d) Repeat the process on the outside surface of the window.
    (e) If punching a hole causes the glazing to disintegrate, halt the 
breakage procedure and proceed with the next step in the compliance 
test.
    S6.3 Determination of ejection reference planes.
    (a) For side windows, the ``ejection reference plane'' is a 
vertical plane parallel to the longitudinal vertical center plane of 
the bus passing through a point located at a lateral distance of 102 
millimeter from the lateral most point on the glazing and surrounding 
frame, with the window in the closed position.
    (b) For rear windows, the ``ejection reference plane'' is a 
vertical plane perpendicular to the longitudinal vertical center plane 
of the bus passing through a point located at a longitudinal distance 
of 102 millimeter from the rear most point on the glazing and 
surrounding frame, with the window in the closed position.
    (c) For roof glass panels/windows, the ``ejection reference plane'' 
is a horizontal plane passing through a point located at a vertical 
distance of 102 millimeter from the highest point on the glazing and 
surrounding frame, with the window/panel in the closed position.
    S7. Test conditions.
    (a) During testing, the ambient temperature is between 18 degrees 
C. and 29 degrees C., at any relative humidity between 10 percent and 
70 percent.
    S8. Guided impactor. The impactor test device has the dimensions 
shown in Figure 1 of this section. It has a total impactor mass of 26 
kilograms and a spring stiffness of 258 Newton per millimeter. The 
impactor is propelled in the horizontal direction in impacts to the 
side and rear daylight openings and is propelled vertically in impacts 
to the roof daylight openings.
[GRAPHIC] [TIFF OMITTED] TP06MY16.042

    Issued on: April 26, 2016.
Raymond R. Posten,
Associate Administrator for Rulemaking.
[FR Doc. 2016-10418 Filed 5-5-16; 8:45 am]
 BILLING CODE 4910-59-P