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This study aimed to clarify the relationship between truck-pedestrian crash impact velocity and the risks of serious injury and fatality to pedestrians. We used micro and macro truck-pedestrian accident data from the Japanese Institute for Traffic Accident Research and Data Analysis (ITARDA) database. We classified vehicle type into five categories: heavy-duty trucks (gross vehicle weight [GVW] ≥11 × 103 kg [11 tons (t)], medium-duty trucks (5 × 103 kg [5 t] ≤ GVW < 11 × 103 kg [11 t]), light-duty trucks (GVW <5 × 103 kg [5 t]), box vans, and sedans. The fatality risk was ≤5% for light-duty trucks, box vans, and sedans at impact velocities ≤ 30 km/h and for medium-duty trucks at impact velocities ≤20 km/h. The fatality risk was ≤10% for heavy-duty trucks at impact velocities ≤10 km/h. Thus, fatality risk appears strongly associated with vehicle class.

Compared with petroleum fuel, liquefied petroleum gas (LPG) demonstrates advantages in low CO2 emission because of propane and butane, which are the main components of LPG, making H/C ratio higher. In addition, LPG is suitable for high efficient operation of a spark ignition (SI) engine due to its higher research octane number (RON). Because of these advantages, that is, diversity of energy source and reduction of CO2, in the past several years, LPG vehicles have widely used as the alternate to gasoline vehicles all over the world. Consequently, it is absolutely essential for the performance increase of LPG vehicles to comprehend the combustion characteristics of LPG and to obtain the guideline for engine design and calibration. In this study, an LPG-SI engine was built up by converting fuel supply system of an in-line 4-cylinder gasoline engine, which has 1997 cm3 displacement with MPI system, to LPG liquid fuel injection system [1].

Real-time analysis of benzene in automobile exhaust gas was performed using the Jet-REMPI (supersonic jet / resonance enhanced multi-photon ionization) method. Real-time benzene concentration of two diesel trucks and one gasoline vehicle driving in Japanese driving modes were observed under ppm level at 1 s intervals. As a result, it became obvious that there were many differences in their emission tendencies, because of their car types, driving conditions, and catalyst conditions. In two diesel vehicle, benzene emission tendencies were opposite. And, in a gasoline vehicle, emission pattern were different between hot and cold conditions due to the catalyst conditions.

A prototype CNG engine for heavy-duty trucks has been developed. The engine had sufficient output in practical use, and the green-house gas emission rate was below that of the base diesel engine. Furthermore, the NOx emission rate was reduced to 0.16 g/kWh in the JE05 mode as results of having fully adjusted air fuel ratio control. The measured emission characteristics of particles from the prototype CNG engine demonstrated that oil consumption was related to the number of particles. Moreover, when oil consumption is at an appropriate level, the accumulation mode particles are significantly reduced, and the nuclei mode particles are fewer than those of diesel-fueled engines.

Over the last few years much interest has been shown in Dimethyl Ether (DME) as a new fuel for diesel cycle engines. DME combines the advantages of a high cetane number with soot-free combustion, making it eminently suitable for compression engines. According, however, to past engine test results, the engine output of a DME engine lacking compatibility as a DME injection system, is low in comparison with a diesel engine. Required is development of a DME injection system conforming to DME properties. The purpose of this work is to investigate the feasibility of DME application for a conventional jerk-type in-line injection system that has the actual result of use of a comparatively low lubricity fuel such as methanol.

As countermeasures against global warming caused by carbon dioxide, improvement of automotive fuel economy to lower CO2 emission becomes important. In order to promote less CO2 vehicles, appropriate methods to evaluate vehicle fuel economy performance are needed. However, the existing fuel economy test is limited to passenger cars and light duty trucks. The test is executed on a chassis dynamometer. However, if this test method is applied to heavy-duty vehicles (HDV), a large sized chassis dynamometer is needed. Furthermore, heavy duty vehicles have wide variations in a combination of an equipped engine, body shape, a transmission gear, a permissible limit of pay load, and so on. This leads to the increase in the number of chassis dynamometer tests. Therefore, it is difficult to use chassis dynamometer test to evaluate HDV fuel economy performance.