Performance of trucks and LCV in slopes and long downhill slopes: the ineffectiveness of the MTC parameter - maximum traction capacity to guarantee operations safety and legality

• Grant number: 05/00753-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2005
• End date: October 31, 2006
• Field of knowledge: Engineering - Transportation Engineering - Transportation Operations
• Principal Investigator: João Alexandre Widmer
• Grantee: Leandro Pugliesi de Souza
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

LCVS - Long Combination Vehicle have the MTC - Maximum Traction Capacity as one of the regulation parameters, demanded by CONTRAN - Conselho Nacional de Trânsito, the Brazilian government body that is responsible for the regulamentation of the law established in the CTB - Código de Trânsito Brasileiro. MTC is a parameter determined by the manufacturer of a tractor unit through the resistance analysis of the main mechanical parts in the power train, like gear box, cardan axle and differential, responsible for the transmission of the traction force, produced in engine, to the tractor axles. Resolution number 68/98 of CONTRAN establishes that there has to be a compatibility between the limit of MTC and the GCW Gross Combination Vehicle Weight. The CTB, in its article 62 however says: "the minimum speed shall not be inferior to the half of the established maximum speed, respecting the operational conditions of traffic and of the highway ". The Resolution number 777 of CONTRAN establishes engine braking conditions compatible with the European norms defined in ECE-R13, which are also included in the Brazilian norms NB 1253 and 1255 of ABNT - Associação Brasileira de Normas Técnicas. The present work questions the efficacy of the MTC parameter as a valid parameter to assure safety and traffic fluidity conditions of LCV on highways, analyzing technical aspects of the locomotion of tractor units and the technical requirements of CONTRAN. As the guaranty of mechanic resistance of the truck does not determine its good or bad performance on the highway the questioning appears to be warranted. The deficiency in the traction/GCW relation of the majority of the Brazilian truck and LCV fleet causes queueing up on upgrades and downgrades stretches of the highways, due to low speeds of operation of those vehicles, compromising safety and traffic fluidity. The expected result of this investigation is a theoretical demonstration of the inefficacy of the MTC parameter as a regulation form, and the elaboration of a expedite method that allows authorities to technically compatibility conditions of cargo transport vehicles with the geometrical conditions of critical highway segments. (AU)