The Federal Motor Carrier Safety Administration has requested approval from the Office of Management and Budget for approval of a study on warning devices for stopped commercial motor vehicles. This is an experimental study that requires data collection for evaluating whether warning devices meaningfully influence crash-relevant aspects of human performance in the presence of a parked or disabled commercial motor vehicle, and if so, how and to what extent.

These data collection efforts are expected to require the participation of 256 CMV drivers.

FMCSA regulations require specific warning devices to be carried on all CMVs and, except in the case of necessary traffic stops, be deployed near the vehicle whenever it is stopped on the road or shoulder. The regulations prescribe specific rules concerning how and where the warning devices must be placed, based on road and traffic attributes (e.g., whether the road is straight or curved, whether the vehicle is stopped in a business or residential district, whether the road is divided or undivided, etc.) as well as the presence of conditions affecting visibility (e.g., time of day, physical obstructions, etc.). These requirements follow from the notion that increasing the conspicuity of a parked or disabled vehicle makes it easier to see and recognize, thereby reducing the risk of a crash involving passing motorists.

The study is intended to assess how deployment of warning devices might work with automated driving system technology and whether drivers deploying warning devices incur additional safety risks. The notice also asserts there are historically unresolved questions of whether the use of such devices improves traffic safety and, if so, how and to what extent.