Semi-automated Transit Authorization of Exceptional Transport Vehicles: Case-Study Application on a Prestressed Concrete Bridge

A possible methodology for streamlining the structural safety verifications, needed for authorizing the transit of exceptional transportation vehicles (ETV) on road bridges, is discussed. ETVs, and mainly those classified as such due to total weight, entail a legal obligation of supporting the granting or not of transit permits, by structural calculations that verify adequate load-bearing capacity of the highway bridges the ETV will go over. This method treats vehicle weight and number of axles of a generic fictitious ETV as parameters and is based on progressively increasing the value of both. Cross-sectional forces on bridges due to thusly defined ETVs are expediently obtained using influence lines, then inserted in code-mandated load combinations and compared to structural capacity that is calculated using material properties considered in the original design, deduced from in-situ testing data, or evaluated from simulated design based on the practice at time of construction. Although virtually applicable to any structural typology, a case-study application to an existing underpass with prestressed concrete deck is considered here.