FMVSS 217: Bus Emergency Exits explained.

What FMVSS 217 says it is for

The eCFR heads this section "Standard No. 217; Bus emergency exits and window retention and release." Under 49 CFR part 571, the Federal Motor Vehicle Safety Standards are the numbered standards that set safety performance requirements for motor vehicles and equipment. The text below is quoted from 571.217 as current through October 29, 2026.

This standard establishes requirements for the retention of windows other than windshields in buses, and establishes operating forces, opening dimensions, and markings for bus emergency exits.

The purpose of this standard is to minimize the likelihood of occupants being thrown from the bus and to provide a means of readily accessible emergency egress.

What it applies to

The application section of the standard says:

This standard applies to buses, except buses manufactured for the purpose of transporting persons under physical restraint.

Applicability is decided by the text of the standard as written, including any exclusions it lists, and by the date-specific rules in it. This page does not decide whether a particular vehicle or item is covered.

How the standard is organized

The eCFR text of 571.217 has these top-level sections:

• S1: Scope
• S2: Purpose
• S3: Application
• S4: Definitions
• S5: Requirements
• S6: Test conditions

In all, the text has 44 numbered headings. Use the finder above to search them; for example, a search for "test" lists the headings that mention tests.

Second-level headings at a glance

These are the numbered sub-sections one level below the top, in order (first 9 of 9):

• S5.1 Window retention
• S5.2 Provision of emergency exits
• S5.3 Emergency exit release
• S5.4 Emergency exit opening
• S5.5 Emergency exit identification
• S6.1 The vehicle is on a flat, horizontal surface
• S6.2 The inside of the vehicle and the outside environment are kept at any temperature from…
• S6.3 For the window retention test, windows are installed, closed, and latched (where latches…
• S6.4 For the emergency exit release and extension tests, windows are installed as in S6.3…

Key requirements, quoted from the text

These are excerpts from the requirements sections of 571.217, in the order the standard presents them. Long paragraphs are shortened where marked with [...]; the eCFR has the complete text, tables and figures, which this page omits.

S5.1 Window retention. Except as provided in S5.1.2, each piece of window glazing and each surrounding window frame when tested in accordance with the procedure in S5.1.1 under the conditions of S6.1 through S6.3, 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 4-inch diameter sphere under a force, including the weight of the sphere, of 5 pounds until any one of the following events occurs: (a) A force of 1,200 pounds is reached. (b) At least 80 percent of the glazing thickness has developed cracks running from the load contact region to the periphery at two or more points, or shattering of the glazing occurs. (c) The inner surface of the glazing at the center of force application has moved relative to the window frame, along a line perpendicular to the undisturbed [...]

S5.1.1. An increasing force shall be applied to the window glazing through the head form specified in Figure 4, outward and perpendicular to the undisturbed inside surface at the center of the area of each sheet of window glazing, with a head form travel of 2 inches per minute.

S5.1.2. The requirements of this standard do not apply to a window whose minimum surface dimension measured through the center of its area is less than 8 inches.

Defined terms

The standard defines 10 terms in its definitions section; the first 10 are quoted here from the eCFR.

• Adjacent seat means a designated seating position located so that some portion of its occupant space is not more than 10 inches from an emergency exit, for a distance of at least 15 inches measured horizontally and parallel to the exit.
• Mid-point of the passenger compartment means any point on a vertical transverse plane bisecting the vehicle longitudinal centerline that extends between the two vertical transverse planes which define the foremost and rearmost limits of the passenger compartment.
• Occupant space means the space directly above the seat and footwell, bounded vertically by the ceiling and horizontally by the normally positioned seat back and the nearest obstruction of occupant motion in the direction the seat faces.
• Passenger compartment means space within the school bus interior that is between a vertical transverse plane located 76 centimeters in front of the forwardmost passenger seating reference point and a vertical transverse plane tangent to the rear interior wall of the bus at the vehicle centerline.
• Post and roof bow panel space means the area between two adjacent post and roof bows.
• Push-out window means a vehicle window designed to open outward to provide for emergency egress.
• Sliding window means a bus window designed to open by moving vertically or horizontally to provide emergency egress.
• Wheelchair means a wheeled seat frame for the support and conveyance of a physically disabled person, comprising at least a frame, seat, and wheels.
• Wheelchair securement anchorage means the provision for transferring wheelchair securement device loads to the vehicle structure.
• Wheelchair securement device means a strap, webbing or other device used for securing a wheelchair to the school bus, including all necessary buckles and other fasteners.

Limits of this page

This page quotes the text of 49 CFR 571.217 as published in the eCFR, current through October 29, 2026. It omits tables, figures, cross-referenced test procedures in other parts, and the preambles and rulemaking history that explain the rule. It does not tell you whether a given vehicle, part or product complies, how to run a test, or what a manufacturer must certify. Compliance questions go to the manufacturer's engineers, qualified counsel or NHTSA. The eCFR is an editorial compilation, not the official legal edition of the Federal Register.

Sources

Sources opened and read November 2, 2026.

• eCFR: 49 CFR 571.217, Standard No. 217; Bus emergency exits and window retention and release. (current through October 29, 2026) (read November 2, 2026)
• eCFR: 49 CFR part 571, Federal Motor Vehicle Safety Standards (current through October 29, 2026) (read November 2, 2026)