The presentation deals with the development of a design code for bridges. It is focused on the calibration process with the objective to determine load and resistance factors for AASHTO. The major steps in the code calibration procedure include the development of load and resistance models, reliability analysis procedure, selection of the target reliability and selection of the load and resistance factors. Bridge live load is based on the available extensive weigh-in-motion (WIM) data. The weight of vehicles and traffic volume is strongly site-specific. The WIM trucks were run over the influence lines to determine the load effects such as moments and shears. The parameters of the dynamic load are derived from the field measurements. A considerable database is gathered on material strength: concrete, reinforcing steel, and prestressing steel. The test results were provided by industry and they are analyzed to determine the cumulative distribution functions and other statistical parameters. The statistical parameters of concrete strength depends on fc’. A very small coefficient of variation is observed for reinforcing steel and even smaller for prestressing strands. The reliability analysis is performed to determine the reliability indices for components designed according to the AASHTO Code prior to calibration and after calibration. The results confirmed that the reliability-based calibration results in a consistent design, with reliability indices being close to the target value.