Pierre Villeneuve, Standard Technician
Trans Canada Highway
Drummondville, (Quebec) J2B 6V4
Dear Mr. Villeneuve:
This responds to your request for an interpretation of Federal Motor Vehicle Safety Standard No. 217, Bus emergency exits and window retention and release. Specifically, you wish to know "how many emergency exits" are needed on each side of a non-school bus over 4,536 kg (10,000 pounds) GVWR with "21 passengers" (not including the driver).
Standard No. 217 requirements applicable to the bus at issue are at S188.8.131.52 and S184.108.40.206, Buses with GVWR of more than 10,000 pounds. S220.127.116.11 requires that non-school buses provide unobstructed openings for emergency exits based on the number of "designated seating positions on the bus," a term which includes the drivers seat. Thus, the bus at issue has 22 designated seating positions.
Standard No. 217 does not specify the number or types (i.e., doors versus windows) of emergency exits that must be provided. However, the standard specifies the total area of the unobstructed openings for emergency exits that must be provided. For the bus at issue, S18.104.22.168 specifies that the unobstructed openings for emergency exits must amount to 9,504 square centimeters (cm) (432 cm x 22 designated seating positions). At least 3,801.6 cm (40 percent) of the total required area of unobstructed openings shall be provided on each side (i.e., the right side or left side) of a bus.
The following explains how the 9,504 cm is to be allocated among the right and left sides of the bus and the rear emergency exit.
Emergency exits on the right side of the bus You stated that there was only one door, opposite the drivers seat, for entrance and egress. If the front door meets Standard No. 217 emergency exit requirements, it can be considered an emergency exit. See June 30, 1988, letter to Mr. Terry K. Brock (copy enclosed): "As long as the front door meets all applicable requirements for emergency exits under Standard No. 217, the door can be considered as an emergency exit. " However, as specified in S22.214.171.124, regardless of its actual area, the front door cannot be credited with more than 3,458 cm of the total area requirement.
Subtracting the square centimeters of the front door (not to exceed 3,458 square centimeters) from 3,801.6 cm, the remainder (of the area representing the unobstructed openings for the right side emergency exit) may be allocated to a side exit such as a window. The combined unobstructed opening area for the front door and the right side emergency exit window must total at least 3,801.6 cm.
Emergency exits on the left side of the bus The combined unobstructed openings for emergency exits for the left side of the bus must also be at least 3,801.6 cm. The emergency exits may consist of a left side emergency door and an emergency exit window, or may consist of emergency exit windows only.
Rear emergency exits Although you did not ask about rear emergency exits, please note that the unobstructed opening for the rear emergency exit must total at least 1900.8 cm (9,504 cm (total unobstructed area) minus 3801.6 cm (right side) minus 3801.6 cm (left side)). S126.96.36.199 states that when the bus configuration precludes installation of an accessible rear exit (such as a rear exit door), a roof exit that meets the requirements of S5.3 through S5.5 when the bus is overturned on either side, with the occupant standing facing the exit, shall be provided in the rear half of the bus.
I hope this information is helpful. If you have any further questions, please feel free to contact Dorothy Nakama at this address or at (202) 366-2992.