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The timing and associated levels of braking between initial brake pedal application and actual maximum braking at the wheels for a tractor-semitrailer are important parameters in understanding vehicle performance and response. This paper presents detailed brake timing information obtained from full scale instrumented testing of a tractor-semitrailer under various conditions of load and speed. Brake timing at steer, drive and semitrailer brake positions is analyzed for each of the tested conditions. The study further seeks to compare the full scale test data to predicted response from detailed heavy truck computer vehicle dynamics simulation models available in commercial software packages in order to validate the model's brake timing parameters. The brake timing data was collected during several days of full scale instrumented testing of a tractor-semitrailer performed at the Transportation Research Center, in East Liberty, Ohio.

The ability of a simulation model to accurately predict vehicle response is investigated in this paper. This study seeks to compare full-scale tractor-semitrailer straight-line braking test data to predicted response from a detailed heavy truck computer vehicle dynamics simulation model. The model, Simulation MOdel Non-linear (SIMON), is a vehicle dynamic simulation model within the Human Vehicle Environment (HVE) software environment. This computer program includes a vehicle dynamic model capable of simulating vehicle motion in 3-dimensional environments and includes Brake Designer and ABS Simulation Models. The results of several days of full scale instrumented testing of a tractor-semitrailer performed at the Transportation Research Center, in East Liberty, Ohio are presented.

Investigators of vehicular incidents often seek to recover data stored within on-board computer systems. For commercial vehicles, the primary source for this information is the engine control module (ECM). The data stored in these modules, not unlike passenger vehicles, varies widely among manufacturers, as do the hardware and software required to recover such data. Further, the options, and associated risks, involved with attempting to recover this data has a similarly wide variance relative to the engine manufacturer, incident related circumstances, and the tools currently available to perform such downloads. There are two primary paths available to obtain this data: (1) via the vehicle data bus (e.g. SAE J1939 or J1708 ) or (2) direct-to-module (DTM) connection. When using the DTM method, power is applied to an ECM, and the module measures the various engine control and monitoring components for validity.

This paper documents the vehicle response of a tractor-semitrailer following a sudden air loss (Blowout) in a steer axle tire while traveling at highway speeds. The study seeks to compare full-scale test data to predicted response from detailed heavy truck computer vehicle dynamics simulation models. Full-scale testing of a tractor-semitrailer experiencing a sudden failure of a steer axle tire was conducted. Vehicle handling parameters were recorded by on-board computers leading up to and immediately following the sudden air loss. Inertial parameters (roll, yaw, pitch, and accelerations) were measured and recorded for the tractor and semitrailer, along with lateral and longitudinal speeds. Steering wheel angle was also recorded. These data are presented and also compared to the results of computer simulation models. The first simulation model, SImulation MOdel Non-linear (SIMON), is a vehicle dynamic simulation model within the Human Vehicle Environment (HVE) software environment.

There have been many studies regarding the stability of vehicles following a sudden air loss event in a tire. Previous works have included literature reviews, full-scale vehicle testing, and computer modeling analyses. Some works have validated physics-based computer vehicle simulation models for passenger vehicles and other works have validated models for heavy commercial vehicles. This work describes a study wherein a validated vehicle dynamics computer model has been applied to extrapolate results to higher event speeds that are consistent with travel speeds on contemporary North American highways. This work applies previously validated vehicle dynamics models to study the stability of a five-axle commercial tractor-semitrailer vehicle following a sudden air loss event for a steer axle tire. Further, the work endeavors to understand the analytical tire model for tires that experience a sudden air loss.