(a) Each bus shall be equipped with one rear emergency door that opens outward and is hinged on the right side (either side in the case of a bus with a GVWR of 4,536 kilograms or less); or

(b) Each bus shall be equipped with one emergency door on the vehicle's left side that is hinged on its forward side and meets the requirements of §5.2.3.2.(a), and a push-out rear window that provides a minimum opening clearance 41 centimeters high and 122 centimeters wide and meets the requirements of §5.2.3.2(c).

S5.3 Emergency exit release.

S5.3.1 Each emergency exit not required by S5.2.3 shall be releasable by operating one or two mechanisms located within the regions specified in Figure 1, Figure 2, or Figure 3. The lower edge of the region in Figure 1, and Region B in Figure 2, shall be located 13 centimeters above the adjacent seat, or 5 centimeters above the arm rest, if any, whichever is higher.

S5.3.2 When tested under the conditions of S6., both before and after the window retention test required by S5.1, each emergency exit not required by S5.2.3 shall allow manual release of the exit by a single occupant using force applications each of which conforms, at the option of the manufacturer, either to S5.3.2 (a) or (b) of this section. Each exit shall have not more than two release mechanisms. In the case of exits with one release mechanism, the mechanism shall require two force applications to release the exit. In the case of exits with two release mechanisms, each mechanism shall require one force application to release the exit. At least one of the force applications for each exit shall differ from the direction of the initial motion to open the exit by not less than 90° and no more than 180°.

(a) Low–force application.

(1) Location. As shown in Figure 1 or Figure 3.

(2) Type of motion. Rotary or straight.

(3) Magnitude. Not more than 20 pounds.

(b) High force application.

(a)(2) Type of motion: Rotary or straight.

(a)(3) Magnitude: Not more than 89 newtons.

(b) Emergency roof exits—High–force application.

(b)(1) Location: Within the high–force access regions shown in Figure 3b, in the case of buses whose roof exits are not offset from the plane specified in S5.2.3.2(b)(5). In the case of buses which have roof exits offset from the plane specified in S5.2.3.2(b)(5), the amount of offset shall be used to recalculate the dimensions in Figure 3B for the offset exits.

(b)(2) Type of motion: Straight and perpendicular to the undisturbed exit surface.

(b)(3) Magnitude: Not more than 178 newtons.

S5.4 Emergency exit opening.

S5.4.1 After the release mechanism has been operated, each emergency exit not required by S5.2.3 shall, under the conditions of S6., both before and after the window retention test required by S5.1, using the reach distances and corresponding force levels specified in S5.3.2, allow manual opening by a single occupant to a position that provides an opening large enough to admit unobstructed passage, keeping a major axis horizontal at all times, of an ellipsoid generated by rotating about its minor axis an ellipse having a major axis of 50 centimeters and a minor axis of 33 centimeters.

S5.4.2 School bus emergency exit opening.

S5.4.2.1 School buses with a GVWR of more than 10,000 pounds.

(a) Emergency exit doors. After the release mechanism has been operated, each emergency exit door of a school bus shall, under the conditions of S6., before and after the window retention test required by S5.1, using the force levels specified in S5.3.3, be manually extendable by a single person to a position that permits:

(a)(1) In the case of a rear emergency exit door, an opening large enough to permit unobstructed passage into the bus of a rectangular parallelepiped 1,145 millimeters (45 inches) high, 610 millimeters (24 inches) wide, and 305 millimeters (12 inches) deep, keeping the 1,145 millimeter (45 inch) dimension vertical, the 610 (24 inch) millimeter dimension parallel to the opening, and the lower surface in contact with the floor of the bus at all times, until the bottom edge of the rearmost surface of the parallelepiped is tangent to the plane of the door opening; and

(a)(2) In the case of a side emergency exit door, an opening at least 114 centimeters high and 61 centimeters wide.

(a)(2) (i) except as provided in paragraph (a)(2)(ii) of this section, no portion of a seat or a restraining barrier shall be installed within the area bounded by the opening of a side emergency exit door, a vertical transverse plane tangent to the rearward edge of the door opening frame, a vertical transverse plane parallel to that plane at a distance of 30 centimeters forward of that plane, and a longitudinal vertical plane passing through the longitudinal centerline of the bus. (See Figure 5A).

(a)(2) (ii) A seat bottom may be located within the area described in paragraph (a)(2)(i) of this section if the seat bottom pivots and automatically assumes and retains a vertical position when not in use, so that no portion of the seat bottom is within the area described in paragraph (i) when the seat bottom is vertical. (See Figure 5B).

(a)(2)(iii) No portion of a seat or restraining barrier located forward of the area described in paragraph (a)(2)(i) of this section and between the door opening and a longitudinal vertical plane passing through the centerline of the bus shall extend rearward of a vertical transverse plane tangent to the forwardmost portion of a latch mechanism on the door. (See Figures 5B and 5C).

(3)(i) Each emergency exit door of a school bus shall be equipped with a positive door opening device that, after the release mechanism has been operated, under the conditions of S6, before and after the window retention test required by S5.1—

(3)(i)(A) Bears the weight of the door;

(3)(i)(B) Keeps the door from closing past the point at which the door is perpendicular to the side of the bus body, regardless of the body's orientation; and

(3)(i)(C) Provides a means for release or override.

(3)(ii) The positive door opening device shall perform the functions specified in paragraph (a)(3)(i)(A) and (B) of this section without the need for additional action beyond opening the door past the point at which the door is perpendicular to the side of the bus body.

(b) Emergency roof exits. After the release mechanism has been operated, each emergency roof exit of a school bus shall, under the conditions of S6, before and after the window retention test required by S5.1, using the force levels specified in S5.3.3, be manually extendable by a single person to a position that permits an opening at least 41 centimeters high and 41 centimeters wide.

(c) Emergency exit windows. After the release mechanism has been operated, each emergency exit window of a school bus shall, under the conditions of S6., both before and after the window retention test of S5.1, using force levels specified in S5.3.3.2, be manually extendable by a single occupant to a position that provides an opening large enough to admit unobstructed passage, keeping a major axis horizontal at all times, of an ellipsoid generated by rotating about its minor axis an ellipse having a major axis of 50 centimeters and a minor axis of 33 centimeters.

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, except that the parallelepiped dimension for the opening of the rear emergency door or doors shall be 45 inches high, 22 inches wide, and 6 inches deep.

S5.4.3 Restriction on wheelchair anchorage location.

S5.4.3.1 Except as provided in paragraph S5.4.3.2 of this section, no portion of a wheelchair securement anchorage shall be located in a school bus such that:

(a) In the case of side emergency exit doors, any portion of the wheelchair securement anchorage is within the space bounded by the interior side wall and emergency exit door opening, transverse vertical planes 305 mm (12 inches) forward and rearward of the center of any side emergency exit door restricted area, and a longitudinal vertical plane through the longitudinal centerline of the school bus, as shown in Figure 6A and Figure 6B.

(b) In the case of rear emergency exit doors in school buses, using the parallelepiped described in S5.4.2.1(a)(1) (for school buses with a GVWR greater than 10,000 lb) or S5.4.2.2 (for school buses with a GVWR of 10,000 lb or less), when the parallelepiped is positioned, as described in S5.4.2.1(a), flush with the floor and with the rear surface of the parallelepiped tangent to the opening of the rear emergency exit door, there must not be any portion of a wheelchair securement anchorage within the space occupied by the parallelepiped or within the downward vertical projection of the parallelepiped, as shown in Figure 6C.

S5.4.3.2 The restriction in S5.4.3.1(a) of this section does not apply to tracks or track-type devices that are used for mounting seats and/or for wheelchair securement devices.

S5.5 Emergency exit identification.

S5.5.1 In buses other than school buses, and except for windows serving as emergency exits in accordance with S5.2.2.3(b) and doors in buses with a GVWR of 10,000 pounds or less, each emergency exit door shall have the designation "Emergency Door" or "Emergency Exit," and every other emergency exit shall have the designation "Emergency Exit" followed by concise operating instructions describing each motion necessary to unlatch and open the exit, located within 16 centimeters of the release mechanism.

EXAMPLES

(1) Lift to Unlatch, Push to Open
(2) Lift Handle and Push out to Open

When a release mechanism is not located within an occupant space of an adjacent seat, a label meeting the requirements of S5.5.2 that indicates the location of the nearest release mechanism shall be placed within the occupant space.

Example: "Emergency Exit Instructions Located Next to Seat Ahead"

S5.5.2 In buses other than school buses. Except as provided in S5.5.2.1, each marking shall be legible, when the only source of light is the normal nighttime illumination of the bus interior, to occupants having corrected visual acuity of 20/40 (Snellen ratio) seated in the adjacent seat, seated in the seat directly adjoining the adjacent seat, and standing in the aisle location that is closest to that adjacent seat. The marking shall be legible from each of these locations when the other two corresponding locations are occupied.

S5.5.2.1 If the exit has no adjacent seat, the marking must meet the legibility requirements of S5.5.2 for occupants standing in the aisle location nearest to the emergency exit, except for a roof exit, which must meet the legibility requirements for occupants positioned with their backs against the floor opposite the roof exit.

S5.5.3 School Bus.

(a) Each school bus emergency exit provided in accordance with S5.2.3.1 shall have the designation "Emergency Door" or "Emergency Exit," as appropriate, in letters at least 5 centimeters high, of a color that contrasts with its background. For emergency exit doors, the designation shall be located at the top of, or directly above, the emergency exit door on both the inside and outside surfaces of the bus. The designation for roof exits shall be located on an inside surface of the exit, or within 30 centimeters of the roof exit opening. For emergency window exits, the designation shall be located at the top of, or directly above, or at the bottom of the emergency window exit on both the inside and outside surfaces of the bus.

(b) Concise operating instructions describing the motions necessary to unlatch and open the emergency exit shall be located within 15 centimeters of the release mechanism on the inside surface of the bus. These instructions shall be in letters at least 1 centimeter high and of a color that contrasts with its background.

Examples:

(1) Lift to Unlatch, Push to Open

(2) Turn Handle. Push Out to Open