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Vehicle light-weighting of late has gained a lot of importance across the automotive industry. With the developed nations like the U.S. setting stringent fuel economy targets of 54.5 mpg by 2025, the car industry's R&D is taking light weighting to a whole new level, besides improving engine efficiency. The commercial vehicles on the other hand are also gradually catching up when it comes to using alternate material for weight reduction. This paper will discuss light-weighting in the context of buses though. For a typical bus, the contribution of shell structure weight in the bus body weight is more than 40%. This qualifies as the area with a huge potential for weight saving. On the other hand the shell structure forms the base skeleton of the bus body providing it with adequate strength and stiffness for meeting both functional (bending & torsional stiffness) and passive safety requirements (rollover compliance).

‘To achieve more from less’ has been the oft-quoted phrase in auto industry for quite some time. This philosophy has many analogies like fuel efficiency, modularity, weight reduction, alternative fuels etc. Of these ‘modularity’ is seen as an effective tool, especially for automotive OEMs catering to a wide portfolio of similar products. This paper discusses the implications of modularization on a passenger bus OEM, by taking the ‘bus super structure’ as a test case. The modularized bus structure is compared with the conventional structure for design strength, safety, weight and more importantly manufacturing flexibility. The challenges faced in each of these aspects are discussed. From the study it was understood that the task of manufacturing body modules and interfaces is complex and it calls for a complete revamp of existing fixtures, material handling equipment and even the prescribed tolerances.

The aerodynamic drag of cars, trucks and buses have been closely examined over the years. Many of them focus on the front end and to some extent on rear end of the vehicles [1]. Of course these are the two surfaces that contribute to more than 85 % of the total drag. This is because these surfaces are almost normal to the direction of air flow and hence create enormous pressure differences and hence drag. A lot of optimization has also gone into these, by way of reducing the sharp corners at ‘A’ pillars, introducing aerodynamic dome and even ‘boat tail flap plates’ [2-3] for some trailers. However, part of the vehicle that has not received sufficient attention in aerodynamic drag considerations is the ‘transverse outer profile’ of vehicle. This transverse outer profile is nothing but the cross sectional profile formed by the vehicle's sides, roof and their integration.