Md. Code Regs. 11.19.02.17

Current through Register Vol. 51, No. 12, June 14, 2024

Section 11.19.02.17 - Body Construction - External

A. External structural construction shall be of rust resistant, zinc coated, prime commercial cold rolled quality steel, or a material with the strength at least equivalent to steel, and shall be fire resistant. The following apply:

(1) Metal parts that will be painted shall be chemically cleaned, etched, zinc phosphate coated, and zinc chromate or epoxy primed or conditioned by equivalent process;

(2) Particular attention shall be given to lapped surfaces, welded connections of structural members, cut edges, punched or drilled hole areas in sheet metal, closed or box sections, unvented or undrained areas, and surfaces subjected to abrasion during vehicle operation.

B. The overall length of a school vehicle may not exceed 40 feet.

C. Roof Strainers. Two or more roof strainers or longitudinal members shall be provided to connect roof bows, to reinforce the flattest portion of roof skin, and to space roof rows. These strainers may be installed between roof bows or applied externally. They shall extend from the windshield header and when combined with the rear emergency door post, shall function as longitudinal members extending from the windshield header to the rear floor body cross member. At all points of contact between strainers or longitudinal members and other structural material, attachment shall be made by means of welding, riveting, or bolting. After the test load as specified in 49 CFR § 571.220 has been removed, none of the following defects shall be evident:

(1) Failure or separation at joints where strainers are fastened to roof bows;

(2) Appreciable difference in deflection between adjacent strainers and roof bows; or

(3) Twisting, buckling, or deformation of strainer cross section.

D. Side Strainers.

(1) There shall be one or more side strainers or longitudinal members to connect vertical structural members and to provide impact and penetration resistance in the event of contact with other vehicles or objects. The strainers may not be formed in flat strips. The strainers shall be constructed from metal of at least 16 gauge and 3 inches wide. Side strainers shall be installed in an area between the bottom of the window and the bottom of the seat frame and shall extend completely around the bus body except for door openings and body cowl panel. Side strainers shall be fastened to each vertical structural member in any one or any combination of the following methods as long as the stress continuity of the members is maintained:

(a) Installed between vertical members;

(b) Installed behind panels but attached to vertical members;

(c) Installed outside external panels.

(2) The fastening method employed shall be such that the strength of strainers is fully utilized. Side strainers or longitudinal members either may be combined with one of the required rub rails or installed alone as an additional rub rail, as long as separate conditions and physical requirements for rub rails are met. A portion of the side strainer or longitudinal member may not occupy the same vertical position as either rub rail.

E. Rear Corner Reinforcements. Rear corner framing of the bus body between the floor and the window sill and between emergency door posts and last side posts shall consist of at least three structural members applied horizontally or vertically or in another combination to provide additional impact and penetration resistance equal to that provided by frame members in areas of the sides of the body. The structural members shall be securely attached to each end.

F. Floor Sills. There shall be one main body sill at each side post and two intermediate body sills on approximately 10-inch centers. All sills shall be of equal height not to exceed 3 inches and shall extend the width of the body floor except where structural members or features restrict area. The main body sill shall be equivalent to or heavier than 10 gauge and each intermediate body sill shall be equivalent to or heavier than 16 gauge, or each of all body sills shall be equivalent to or greater than 14 gauge. All sills shall be permanently attached to the floor. Connections between the sides and floor system shall be capable of distributing loads from vertical posts to all floor sills. As evidence that this requirement is fulfilled, the following conditions may not occur during or after application of the load:

(1) Appreciable difference in deflection between adjacent sills;

(2) Failure or separation in joints where floor, floor sills, and sides connect;

(3) Twisting, buckling, or deformation of floor sill cross members.

G. The metal of commercial gauges used in the construction of the bus body shall be coated with mill applied zinc, be aluminum coated, or be treated by an equivalent process before the bus is constructed. Included are structural members, inside and outside panels, floor panels, and floor sills. Excluded are door handles, grab handles, stanchions, interior decorative parts, and other interior plated parts.

H. After the load has been removed, the following defects may not be evident at all points of contact between longitudinal members and other structure material:

(1) Failure or separation at joints where longitudinal members are attached to the roof bows;

(2) Appreciable differences in deflection between adjacent longitudinal members and roof bows;

(3) Twisting, buckling, or deformation of longitudinal member cross section.

I. Strength of Structural Joints of School Vehicle Bodies. It is the intent of this regulation to insure that all structural joints within bus bodies which employ discrete attachments, which are between heavy gauge members and those which join panels to panels or panel edges to heavier structures, achieve a significant proportion of the strength of the parent metal. For any of the joints described in this section, it shall be demonstrated by calculation that the shear strength of the joints is at least 60 percent of the yield point strength of the thinnest member. Panels shall be attached to underlying structures, and the above requirements may not apply where panels are attached to underlying structures at points other than the panel edges.

J. One rub rail shall be located approximately at the floor line. The rail shall cover the same longitudinal area as the upper rub rail, except at wheel housings, and shall extend to the radii of the right and left rear corners.

K. One rub rail shall be located on each side of the bus approximately at seat level, and shall extend from the rear side of entrance door completely around the bus body, except for the emergency door, to a point of curvature near the outside cowl (or the corner of the body on transit and metropolitan vehicles) on the left side.

L. Both rub rails shall be:

(1) At least 4 inches in width;

(2) Of 16 gauge steel;

(3) Corrugated or ribbed;

(4) Attached at each body post and all other upright structural members; and

(5) Applied outside the body or outside the body posts. Pressed in or snap on rub rails do not satisfy this requirement.

M. A snow rail, if required, shall be installed the full length of the body skirt.

N. Rub rails may not be an integral part of the body.

Md. Code Regs. 11.19.02.17

Regulations .17 amended effective April 3, 1981 (8:7 Md. R. 643)
Regulations .17 amended as an emergency provision effective July 6, 1983 (10:15 Md. R. 1342); emergency status extended at 10:22 Md. R. 1964 and 11:4 Md. R. 313
Regulations .17A, B amended effective June 18, 1984 (11:12 Md. R. 1063)
Regulations .17 repealed effective June 1, 1987 (14:11 Md. R. 1261)
Regulations .17 adopted effective June 1, 1987 (14:11 Md. R. 1261)
Regulation .17A, J amended effective January 8, 1990 (16:26 Md. R. 2795)
Regulation .17H, I amended effective June 20, 2005 (32:12 Md. R. 1047)