Noise level, whole-body vibration from the driver seat, and the in-cab air quality of heavy-duty diesel vehicles were measured while parked with the engine idling at a truck stop rest area and driven over a prescribed route. Data were collected to serve as baseline data from which future similar studies may determine if (new) truck designs have changed the existing state of these conditions for the drivers. Twenty-seven trucks (model years between 2006 and 2008) were tested; the sample included trucks from fourdifferent manufacturers. Results indicated that slightly higher noise levels occurred while driving on the (Federal) interstate relative to driving on the (State) highway. Overall in-cab noise levels however were found to be below OSHA standard and/or NIOSH recommended values. Evaluation for seating vibration utilized ISO guidelines. Average vibrations in the x-, y- and z-axes for the seats were generally found to be well below standardexposures for an 8-hr driving day. Several exceedances occurred in a fewtrucks; inferior road pavement conditions were thought to have contributed to these higher vibrations. For most trucks, the likely comfort reaction from the vibration magnitude of the driver seat was in the region of the"not uncomfortable" region. Air quality was determined by measuring in-cab concentrations of CO, NOX and PM2.5. Results indicated that trucks havea tendency to self-pollute the cabs during periods of extended parked (engine) idling. Concentrations during several parked-idling scenarios exceeded EPA (NAAQS) for PM2.5. While driving on public roadways, the in-cab concentrations were relatively lower in comparison to the concentrations that were measured during the extended parked-idling conditions.
Abstract