The four types of superstructures used for the purpose of the study are; reinforced concrete I-beam, I-beam reinforced concrete, prestressed I-beam concrete and composite steel I-beam. The analysis and design is done based on the loading rules of the Indian Road Congress (IRC). The impact of the launch on the railroad and the indirect effect of the cost in terms of block cost and cost of speed restriction are studied in detail. In addition, the effect of the use of the sacrificial form with the combination of conventional formwork for the deck slab is studied in detail. Based on the cost of material, as well as the cost of placing above the rail line, RCC T-beam is more economical among the four options. However, the PSC I-section proves to be the most economical when the launching of beams by the hydraulic crane is considered without regard to the indirect cost. The use of sacrificial formwork in roof slabs increases nominal cost when considering the cost of the material, but when its effect is analyzed with the cost component of block cost and the cost of speed restriction turns out to be an economical and judicious selection .
With the implementation of LRFD specifications by the Federal Highway Administration, many state transportation departments (DOTs) have already begun implementing LRFD specifications as developed by the AASHTO. Many aspects of the LRFD specifications are being investigated by DOTs and researchers for a perfect implementation for design and analysis purposes. This paper presents the investigation of various design aspects of post-tensioned box girder bridges designed by LRFD Specifications using conventional or high strength concrete (HSC). A computer spreadsheet application was developed specifically for this research. It is capable of analyzing, designing and evaluating superstructure costs for a post-tensioned box beam bridge cast in place. The optimum design of a post-tensioned box beam is achievable by the correct selection of design variables. The evaluation of costs of superstructures with different geometric and material configurations has led to the development of optimal design diagrams for these types of superstructures. The variables used to develop these graphs include, among others, the length of the section, the depth of the section, the spacing of the web, the tendon profile and the strength of the concrete. It was observed that the HSC allows to achieve significantly longer strand lengths and / or a longer strand spacing that is not attainable when using normal strength concrete.