Interpretation ID: 2857o
Specifications/Inspections Chief
Texas State Purchasing & General Service
Commission
Lyndon Baines Johnson State Office Bldg.
P.O. Box 13047 Capitol Station
Austin, Texas 78711-3047
Dear Mr. Martin:
This is a response to your letter of last year where you stated your concern respecting the installation of "latches" on the rear doors of a school bus of 10,000 lbs or less GVWR (small school bus), and asked a number of questions on release mechanisms for required rear emergency doors on these small school buses. I regret the delay in this response.
You said that the State of Texas has a school bus specification that requires "the first-closed (left-hand) door)" to have a latching mechanism at the top and bottom. Your supplier tells you that this specification conflicts with provisions of Federal safety standard 217, Bus Window Retention and Release (Standard 217). You go on to express your concern that a single mechanism would hold both doors closed, and that this feature increases the risk of injury from accidental or intentional opening. You believe that where a small school bus has two rear doors, if each door is secured independently, then there is a decreased risk of a student's falling through a door opened inadvertently.
Let me begin my answer with some general information on the requirement for a rear emergency door in a small school bus. As your supplier suggests, there can be instances where independently securing the rear doors on a small school bus would violate Standard 217. Paragraph S5.2.3.1 requires a manufacturer of these buses to install either (1) one rear emergency door, or (2) one emergency door on the vehicle's left side and one push-out rear window. Where a manufacturer chooses to meet this requirement by installing one rear emergency door, the door may be hinged on either side of the vehicle.
When a manufacturer installs more than one rear door exit, the question of whether both exits are "emergency doors" under paragraph S5.2.3.1 of Standard 217 depends upon whether one or both doors must be opened for unobstructed passage of a specified parallelepiped under paragraph S5.4.2.2. The purpose of the school bus emergency exit requirements is to facilitate quick and safe rider exit from the vehicle in the event of an emergency. (44 FR 7961, 7962, February 8, 1979.)
Question 1: Are both of the rear doors on small school buses (with GVWR of 10,000 lbs or less) considered "emergency doors" in the context of Paragraph S5.2.3.1 of FMVSS 217?
If a manufacturer installs more than one rear door on a small school bus, and intends one door to be a rear emergency door under S5.2.3.1 and one to be a regular door for loading and unloading passengers, then the designated rear emergency door is a sufficient rear emergency exit so long as it will permit unobstructed passage of the device specified in paragraph S5.4.2.2 of the Standard. In a case such as this one, the manufacturer must label the emergency door appropriately, and otherwise ensure that the designated rear emergency door meets the performance, accessibility, and release requirements for a rear emergency door on a small school bus.
On the other hand, if the manufacturer installs two rear doors on a small school bus, and if both of those doors must be open to accommodate the parallelepiped, then both doors constitute a rear emergency exit under S5.2.3.1. In this case, the two doors together must meet the applicable provisions of Standard 217.
There is yet another possibility that a manufacturer may install a second rear exit and designate it as an emergency exit. Assuming that at least one exit meets Standard 217's requirements for a rear emergency door exit, NHTSA would not prohibit installing this additional emergency exit. However, as the agency long has held, that "extra" emergency exit must comply with Standard 217 provisions applicable to emergency exits in buses other than school buses.
Question 2: Does Paragraph S5.3.3 require separate, independent operation; that is, must one be able to open the left-hand door without first opening the right-hand door from outside of the passenger compartment?
Again, the answer to this question depends upon whether one door can meet the unobstructed test measurement for a required rear emergency door. Let me begin this answer by explaining the release requirements for a rear emergency door on a small school bus.
Under paragraph S5.3.3, a required small school bus rear emergency door generally must have a release mechanism that allows (1) a single person (2) to operate the door manually (3) from in or outside the vehicle's passenger compartment without the use of remote controls or tools (4) irrespective of whether the vehicle's power system fails. (Paragraph S5.3.3 also sets the maximum permissible magnitude of force and the permissible direction in which a force must be applied to operate the release mechanism.)
In an interpretation of March 17, 1982, this agency stated that the release mechanism is the mechanism that keeps the door from opening. In other words, the release mechanism is what you refer to in your letter as the door "latch." If the test device described in my answer to your first question passes through unobstructed only when both doors are open, then the door release mechanism must be operable for both doors from inside the vehicle passenger compartment irrespective of whether a person outside the vehicle operates the outside release mechanism. Further, this same release mechanism must be operable from outside the vehicle. In this circumstance, a separate release mechanism for each door would not comply with the Standard.
If only one door needs to be open, and the manufacturer has designated the second door as an emergency exit, then this additional emergency door still must be operable from inside the passenger compartment. In this case, independent release mechanisms may be appropriate, but a release mechanism on an additional emergency exit need not be operable from outside the vehicle. (S5.3.2.)
If only one door needs to be open to accommodate the parallelepiped, and the manufacturer neither intends the second door to be an emergency door, nor designates it as an emergency exit, then the second door is a regular door for loading and unloading passengers. Standard 217 would be inapplicable to this second door.
Question 3: Does Paragraph S5.3.3 require a warning system to indicate an opened position of any latch or latches on the left-hand door even though this door cannot be opened until after the right-hand door is opened, provided both doors must be opened to insert the 45" high by 22" wide x 6" deep parallelepiped?
If both doors must be opened for unobstructed passage of the specified parallelepiped, then there must be a single emergency release mechanism (or latch) for both doors. In a case such as this, there must be an audible alarm under S5.3.3 whenever the release mechanism is not closed and the vehicle ignition switch is "on." That alarm should sound if either door is unsecured.
Question 4: Would a warning system be required to indicate opened latch or latches on the left-hand door as in 3 above, provided the parallelepiped could be inserted into the passenger compartment through the opened right-hand door with the left-hand door closed?
In your question, the manufacturer may designate either door as the required S5.2.3.1 emergency exit if the door accommodates the test device. The warning system then must sound when the release mechanism on the designated rear emergency door is open and the vehicle ignition switch is "on." For example, if in your question, the manufacturer designated the right-hand door as the required rear door emergency exit, then the warning system must sound whenever the release mechanism for that door is open and the vehicle ignition position is "on." As I stated in Question 1, the second rear door could be an "additional" emergency exit, or a regular means for loading and unloading passengers; then the additional door would have to meet such other requirements as may apply to these exits.
Question 5: Would a latch or latches be required on the left-hand door if both doors had to be opened to insert this parallelepiped even though the left-hand door is close by the latches of the right-hand door?
In this circumstance, Standard 217 would prohibit installing a separate release mechanism on each door. Recall that S5.2.3.1 requires on a small school bus, "one rear emergency door," or one side door and one push-out window. If the manufacturer chooses to install the rear emergency door, then under S5.4.2.2, the specified parallelepiped must pass through that rear emergency door without obstruction. If both doors must be open to accommodate the test device, then both doors constitute the single, rear emergency door which the Standard requires. Under paragraph S5.3.3, the required rear emergency door must have its own release mechanism.
I hope you find this information helpful.
Sincerely,
Erika Z. Jones Chief Counsel
ref:217 d:4/29/88