Adoption of PBBT as an OOS Condition

Although the FMCSRs allow motor carriers and State and local enforcement officials to use PBBTs to determine compliance with the brake performance requirements in 49 CFR 393.52, certain CVSA member jurisdictions and associate members have expressed concerns about past proposals to establish an OOS criterion for CMVs tested on approved PBBTs. FMCSA and others have advocated the adoption of uniform enforcement tolerances for placing vehicles OOS if a vehicle fails to meet a minimum total vehicle brake force as a percentage of GVW of 43.5. However, the industry (1) raised several issues regarding the accuracy and repeatability of PBBT results, to which FMCSA has responded by providing data demonstrating the consistent performance of PBBTs under varying operating conditions, and (2) expressed concerns that FMCSA would seek the adoption of individual wheel-end criteria in the future, to which FMCSA has confirmed would if pursued be subject to a notice-and-comment rulemaking.

PBBTs are devices that can assess vehicle braking capability through quantitative measure of individual wheel brake forces or overall vehicle brake performance in a controlled test. PBBTs provide an objective and consistent measure of vehicle braking performance, irrespective of brake type, energy supply, or actuation method, and without having to crawl underneath the vehicle as with the current inspection method. In addition to having the advantage of being able to measure actual vehicle braking performance, the use of PBBTs has the potential for increased CMV violations found during roadside inspections. No known visual inspection method can determine whether a given brake has adequate braking forces; rather, visual inspections can only detect a potential lack of performance if certain components are missing, damaged, or are out of adjustment. FMCSA believes that measurement of CMV braking performance through the use of PBBTs will translate directly to increased CMV safety.

Considering the supporting information (provided separately) that addresses the concerns noted previously, FMCSA requests that the following item be added to the OOS criterion: 1.p Failing to develop a total brake force as a percentage of gross vehicle or combination weight of 43.5 or more, when tested on an approved PBBT (393.52(a)(4)).