Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Find the Latest Information on the Coronavirus/COVID-19 at FTA's Coronavirus landing page.

United States Department of Transportation United States Department of Transportation

Interpretations of Definitions

The contents of this page do not have the force and effect of law and are not meant to bind the public in any way. This page is intended only to provide clarity to the public regarding existing requirements under the law or agency policies. Recipients and subrecipients should refer to FTA’s statutes and regulations for applicable bus testing requirements.
A test hydrogen fuel cell bus at the Bus Testing Center

The Bus Testing Regulation provides several definitions at 49 CFR Part 665.5 for the purpose of administering the Bus Testing Program. While most of them are self-explanatory, some have required further interpretation. Below are the definitions from the regulation, with FTA’s interpretative guidance in italicized text.

If you have comments, suggestions, or feedback on these interpretations, please contact FTA.

Administrator means the Administrator of the Federal Transit Administration or the Administrator’s designee. 

Automotive means that the bus is not continuously dependent on external power or guidance for normal operation. Intermittent use of external power shall not automatically exclude a bus of its automotive character or the testing requirement.

For example, a bus carrying an on-board engine or batteries with sufficient power and energy to operate the bus normally during revenue service would be an automotive vehicle. A vehicle powered solely by overhead electrical wires would not be considered automotive because it is dependent on an external power source for normal operation, and would therefore not meet the definition of a bus and would not be required to complete FTA Bus Testing. Similarly, a rubber-tired self-powered vehicle that followed a track and therefore had no steering wheel would not meet the definition of a bus. Manufacturers or recipients may contact FTA for case-by-case guidance regarding otherwise bus-like vehicles that don’t clearly fall into or out of the term automotive; for example, a bus-like vehicle normally powered by overhead wires but also equipped with an on-board auxiliary power unit, or a vehicle with a steering wheel that operates some of the time on a guideway.

Bus means a rubber-tired automotive vehicle used for the provision of public transportation service by or for a recipient of FTA financial assistance.

Bus model means a bus design or variation of a bus design usually designated by the manufacturer by a specific name and/or model number.

Bus Testing Facility means the facility used by the entity selected by FTA to conduct the bus testing program, including test track facilities operated in connection with the program.

Bus Testing Report means the complete test report for a bus model, documenting the results of performing the complete set of bus tests on a bus model.

Curb weight means the weight of the bus including maximum fuel, oil, and coolant; but without passengers or driver.

Emissions means the components of the engine tailpipe exhaust that are regulated by the United States Environmental Protection Agency (EPA), plus carbon dioxide (CO2) and methane (CH4).

Emissions control system means the components on a bus whose primary purpose is to minimize regulated emissions before they exit the tailpipe. This definition does not include components that contribute to low emissions as a side effect of the manner in which they perform their primary function (e.g., fuel injectors or combustion chambers).

Final acceptance means the formal approval by the recipient that the vehicle has met all of its bid specifications and the recipient has received proper title.

The FTA interprets final acceptance as the release of FTA funds to the bus manufacturer.

Gross weight, also Gross Vehicle Weight, or GVW, means the seated load weight of the bus plus 150 pounds of ballast for each standee passenger, up to and including, the maximum rated standee passenger capacity identified on the bus interior bulkhead.

Hybrid means a propulsion system that combines two power sources, at least one of which is capable of capturing, storing, and re-using energy.

Major change in chassis design means, for vehicles manufactured on a third-party chassis, a change in frame structure, material or configuration, or a change in chassis suspension type.

Major change in components means: (1) For those vehicles that are not manufactured on a third-party chassis, a change in a vehicle’s engine, axle, transmission, suspension, or steering components; (2) For those that are manufactured on a third-party chassis, a change in the vehicle’s chassis from one major design to another.

Major change in configuration means a change that is expected to have a significant impact on vehicle handling and stability or structural integrity.

Modified third-party chassis or van means a vehicle that is manufactured from an incomplete, partially assembled third-party chassis or van as provided by an OEM to a small bus manufacturer. This includes vehicles whose chassis structure has been modified to include: a tandem or tag axle; a drop or lowered floor; changes to the GVWR from the OEM rating; or other modifications that are not made in strict conformance with the OEM’s modifications guidelines where they exist.

If a bus manufacturer can demonstrate that a modification to a third-party chassis or van is made in strict conformance with the OEM's modifications guidelines, then FTA will generally treat that chassis or van as unmodified.

New bus model means a bus model that— (1) Has not been used in public transportation service in the United States before October 1, 1988; or (2) Has been used in such service but which after September 30, 1988, is being produced with a major change in configuration or a major change in components.

Operator means the operator of the Bus Testing Facility.

Original equipment manufacturer (OEM) means the original manufacturer of a chassis or van supplied as a complete or incomplete vehicle to a bus manufacturer.

Parking brake means a system that prevents the bus from moving when parked by preventing the wheels from rotating.

Partial testing means the performance of only that subset of the complete set of bus tests in which significantly different data would reasonably be expected compared to the data obtained in previous full testing of the baseline bus model at the Bus Testing Facility.

The FTA generally considers a change that may reasonably be expected to have an adverse effect on the data that would be collected from additional testing to be more significant than a change that might reasonably be expected to result in a favorable effect. For example, moving weight from low in the bus to the roof or vice versa would both affect the stability of the bus (as measured by the Safety test), however moving the weight higher would adversely affect stability and would likely require repeating the Safety test, while moving the weight lower would favorably affect stability and probably would not require repeating the Safety test. 

Partial testing report, also partial test report, means a report documenting, for a previously-tested bus model that is produced with major changes, the results of performing only that subset of the complete set of bus tests in which significantly different data would reasonably be expected as a result of the changes made to the bus from the configuration documented in the original full Bus Testing Report. A partial testing report is not valid unless accompanied by the corresponding full Bus Testing Report for the corresponding baseline bus configuration.

Public transportation service means the operation of a vehicle that provides general or special service to the public on a regular and continuing basis consistent with 49 U.S.C. Chapter 53.

“Public transportation [service]” has replaced the obsolete term, “mass transportation [service]. The FTA has interpreted this term to include any transportation service provided using vehicles purchased with FTA capital assistance.

Recipient means an entity that receives funds under 49 U.S.C. Chapter 53, either directly from FTA or through a direct recipient.

The term “grantee” is often used interchangeably with the term, “recipient.”

Regenerative braking system means a system that decelerates a bus by recovering its kinetic energy for on-board storage and subsequent use.

Retarder means a system other than the service brakes that slows a bus by dissipating kinetic energy.
 
Seated load weight means the curb weight of the bus plus the seated passenger load simulated by adding 150 pounds of ballast to each seating position and 600 pounds per wheelchair position.

Service brake(s) means the primary system used by the driver during normal operation to reduce the speed of a moving bus and to allow the driver to bring the bus to a controlled stop and hold it there. Service brakes may be supplemented by retarders or by regenerative braking systems.

Small bus manufacturer means a secondary market assembler that acquires a chassis or van from an OEM for subsequent modification or assembly and sale as 5-year/150,000-mile or 4- year/100,000-mile minimum service life vehicle.

Tailpipe emissions means the exhaust constituents actually emitted to the atmosphere at the exit of the vehicle tailpipe or corresponding system.

Third party chassis means a commercially available chassis whose design, manufacturing, and quality control are performed by an entity independent of the bus manufacturer.

Unmodified mass-produced van means a van that is mass-produced, complete and fully assembled as provided by an OEM. This shall include vans with raised roofs, and/or wheelchair lifts, or ramps that are installed by the OEM or by a party other than the OEM provided that the installation of these components is completed in strict conformance with the OEM modification guidelines.

Unmodified mass-produced vans are categorically exempted from testing only in the 4-year, 100,000-mile service life category; unmodified mass-produced vans offered in the 5-year, 150,000-mile (or higher) service life category are subject to testing.

Unmodified third-party chassis means a third-party chassis that either has not been modified, or has been modified in strict conformance with the OEM’s modification guidelines.

Last updated: Tuesday, June 1, 2021