Systemic Failure: The Ghost Report

A critical report was released April 1985 by the National Highway Traffic Safety Administration focused on reducing braking distances of heavy vehicles. Among the findings it states, “Complete removal or deactivation of the front brakes, a practice which is common among some trucker users, obviously degrades the [braking] situation…” At issue is a rumored report that we are currently working to track down as being the source of the practice. It is remarkable that the NHTSA report did not reference the source of the practice as they annihilated it with this study, hence we are referring to this as a Ghost Report here.

Why is this of interest? The image below shows the unique circumstances from the NHTSA report regarding heavy vehicle braking. The amount of torque that should be applied to the brakes depends on whether the vehicle is loaded or unloaded. The general concepts of braking are (a) sliding uncontrolled is bad (wheels locking up), (b) fish-tailing or jack-knifing is bad (rear wheels lock up), (c) maximum friction is good. The amount of torque best applied to the wheels depends on the center of mass. A loaded vehicle has more mass over the rear wheels; an unloaded vehicle has the center of mass much closer to the front wheels. Therefore, more braking torque is required by the rear wheels rather than the front, but that does not mean that the front torque should always be significantly less or none at all. This point was made clear by the poor performance of the front axle automatic limiting valves (ALV’s) produced at the time. Removing them improved braking performance of the empty heavy vehicles.

So where is the systemic failure? This report, released in 1985, was necessary to enforce the evolving Federal Motor Vehicle Safety Standards No. 121 Air Brake Systems and apply federal oversight to the practice discussed above. The References suggest that this practice had been in place since the early 1970’s. The failure point begins with the idea of disconnecting the front brakes being safe due to the (rumored) Ghost Report. Being “widespread” means that the various trucking businesses and manufacturers were aware of the practice. A lawsuit brought by these entities regarding the stopping distances in the FMVSS 121 standards held the testing procedure in question as well as the reliability of anti-lock brakes. Part of this protest, naturally, was in the cost of meeting the reduced distances in the braking standard for fleets of heavy vehicles. In Systemic Failure, this incorporates (a) making decisions when science is flawed, (b) suppressing reasoned dissent, (c) insular training (inferred), and (d) authority has a conflict of interest.

Fortunately for the safety of drivers on the road with heavy vehicles with disabled/bypassed front brakes, the NHTSA funded the necessary research to prove to the court that this was a flawed practice. It took over a decade to address, however.

Distribution of the Center of Mass (CG) of a heavy vehicle and its trailer during braking.