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 ex- ceptional 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 com- pared to structural capacity that is calculated using material properties considered in the original design, deduced from in-situ test- ing 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.