Interpretation ID: aiam3262
Manager
Mechanical Device Development Advanced Systems Engineering
TRW
Inc.
Building E2
Room 4062
One Space Park
Redondo Beach
California 90278;
Dear Mr. Stefano: This responds to your letter of January 7, 1980, in which you describ an automotive, electronic display device being designed by TRW and asked for a legal opinion as to its potential compliance with Federal Motor Vehicle Safety Standard No. 127, *Speedometers and Odometers*. You noted that, upon installation in a motor vehicle, TRW's device would continuously display vehicle and engine speed readings in the form of a bargraph. In potentially hazardous situations requiring the driver to take extra caution or to shut down the vehicle's engine, the TRW device would intermittently interrupt the display of vehicle and engine speeds with sequences of verbal messages. In light of this, you asked whether the fact that TRW's device would not display the vehicle speed during every moment of vehicle operation would prevent it from complying with Safety Standard No. 127.; Based on our understanding of your design, it appears that alternatin the display of speed and verbal messages would not violate the standard. Although the future development of electronic digital speedometers was considered in the development of Safety Standard No. 127, the specific type of device described in your letter was not contemplated. The agency had expected that all speedometers would continuously display vehicle speed. While the intermittent display feature would apparently not violate Safety Standard No. 127 as it is now written, we are concerned about the possible adverse impact upon traffic safety that this feature might have. In particular, we have in mind the effects of a driver's(sic) being unable to determine vehicle speed when he or she is approaching or negotiating a curve or exit ramp. Rapid deceleration to a particular speed is typically necessary in such situations.; In the case of a speedometer which periodically does not displa vehicle speed for periods of 5 seconds, a vehicle traveling at 55 mph would cover approximately 400 feet in that interval and a vehicle traveling at 40 mph, approximately 300 feet. Although your alternative mode of operation would reduce this interval through flashing the speed for periods of 0.10 seconds, we question whether such a short period would be sufficient to enable drivers to read their speedometers. We solicit any test or research that TRW has done on the safety side effects of your design. A member of the agency's accident avoidance division will contact you to discuss this issue further.; In looking at your design, we noted several aspects of it that woul apparently not comply with Safety Standard No. 127. The design does not appear to be graduated in both miles and kilometers per hour as required by section 4.1.2. Further, the design neither has the numeral 55 nor highlights either that numeral of the point at which vehicle speed equals 55 mph as required by section 4.1.5.; Finally, I would emphasize that this letter represents only th agency's opinion based on the information supplied in your letter. The NHTSA does not formally render judgement on the compliance of any vehicle or equipment design with any safety standard before the manufacturer's certification of its product. It is the manufacturer's responsibility under the law to determine whether its vehicle or equipment comply with all applicable safety standards and regulations and to certify its vehicles in accordance with that determination.; I hope that your will find this response helpful and have not bee inconvenienced by our delay in sending it to your.; Sincerely, Frank Berndt, Chief Counsel