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The poor performance observed over the years starts at the very early age of the bridge, like in California. The literature review suggests that restraining effects on the deck may cause excessive early-age transverse cracking and affect the service performance. Cast-in-place reinforced concrete decks exhibit early numerous and wide transverse cracking in California bridges. Prestressed and reinforced concrete continuous box girder bridges are the most affected by transverse cracking in the decks. In this dissertation, the performance of cast-in-place reinforced concrete decks in California is evaluated considering the increasing traffic in the state, the current and past design provisions and the restraining effects provided by the webs of box girders. Statistical analysis was performed in this study to select the types of structures with the worst performance in California. Box girder bridges with cast-in-place reinforced concrete decks were selected for further analysis. Inspection reports, a cracking database of California bridge decks , and weigh-in-motion (WIM) data of selected sites for live-load evaluation were available for the study. The availability of inspection reports and the cracking database of selected box girder bridges allowed the analysis of deck designs, cracking data, and condition rating over time. The different analyses performed in this research provided insights into the level of traffic in California and how it compares with the rest of the nation and AASHTO LRFD design live loads. The deck detailing was evaluated based on the inspection reports available for 94 cast-in-place box girder bridges. It was found that the main reinforcement spacing does not comply with AASHTO LRFD design requirements and that the truss bar detail is ineffective for the strength limit state. Shrinkage and temperature reinforcement spacing provided was found to be one of the largest in the nation, and the amount of steel reinforcement was very low compared to other states. It was recommended that the spacing should be reduced to a maximum of 9 in. and an increased amount of reinforcement (greater than 0.32% of gross deck area) should be provided for shrinkage and temperature reinforcement to better control the transverse cracking widths in concrete bridge decks. Early-age concrete behavior of two box girder bridges was simulated using the finite element method (FEM) with Abaqus software. Creep and shrinkage, using the Modified B3 Model, properties of concrete at early ages were incorporated into the FEM model to obtain the magnitude of strains in the decks in the first 14 days. Data from two bridge decks constructed in California in 2010 was used to develop restraining factors for the box girder bridges. It was found that restraining effects can be up to 88% in these bridges, verifying the high level of restraint provided by the box girders to the decks.