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In 2015, it has been reported that road traffic fatality rate in Thailand ranks number 2 in the world at 36.2 per 100,000 with an annual estimate of 66 deaths every day. Based on the survey of the Road Safety Group Thailand in 2017, at least one student got injury by school transport each day. A recent survey also revealed that the number of private hire pick-up trucks as school buses in Thailand, especially in upcountry areas, is increasing due to its lower cost in comparison to that of a van or a minibus. To get the optimal capacity as vans or minibuses, pick-up trucks’ roofs were converted for the highest passenger number at the lowest cost. Therefore, to focus on the strength of converted pick-up truck’s roof is required to help reduce losses in terms of both human injury and inside cabin’s damage due to rollover accidents. This article demonstrates an approach to design the vehicle’s roof as a superstructure of school pick-up truck based on design inputs, including structural strength, capability of local motor vehicle mechanics, nature of drivers, and nature of passengers. Explicit dynamic finite element analysis is applied to simulate the investigation on full-scale prototype according to American Federal Motor Vehicle Safety Standard No 220 standard. To validate the numerical analysis results, the roof crush test of full-scale roof prototype is performed. The analysis results showed the accurate prediction on the strength and the corresponding deformations of the full-scale prototype. These findings provide means of evaluating the strength of vehicle’s roof, which can be further applied as a guideline for national regulation. This study is planned to bring this tried prototype: the superstructure of school pick-up truck’s roof, to use in a commercial scale.

One of the most harmful of two-vehicle crashes to passenger vehicle occupants is when the front of passenger vehicle hits and passes underneath the rear of truck. It resulted in 23% of total death from two-vehicle crashes with a truck in 2018 based on data from the U.S. Department of transportation’s Fatality Analysis Reporting System (FARS). To reduce the violence of such accidents, the rear underrun protective device (RUPD) is installed on the rear of heavy goods vehicle (HGV), to cause the crumple zone of the impacting passenger vehicle absorbing the impact energy and prevent the impacting passenger vehicle from getting crushed under the HGV. This article demonstrates an approach to design the RUPD based on design inputs, including the structural strength, the local RUPD builders, and the variation of commercial HGV types in Thailand. The morphological analysis is applied along with brainstorming among design team, local manufacturers, and government agency, to generate a total of 72 potential RUPD solutions. In this study, three potential RUPD designs were proposed as RUPD prototypes for different HGV types to investigate their structural strength in terms of strain, deformation, and maximum reaction force. The explicit dynamic finite element (FE) method was implemented to accurately simulate the structural strength of the RUPD prototype since its results were validated by the real test of full-scale prototype with reference to the UN R58 standard. From the results, all proposed RUPD prototypes satisfied the UN R58 standard and are not violated by test loads at all relevant positions. In addition, different designs of the protective beam, which was found to be the main load-bearing resstive component of RUPD, were proposed. Their structural strength and energy-absorbing capability were examined by FE simulation to allow local RUPD builders to have alternatives for RUPD fabrication depending on their resources and applications. Besides, the proposed design approach in this study could be further applied as a guideline design for other RUPD types in a commercial scale.

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