Japan National Traffic Safety and Environment Laboratory

Tokyo, Japan

Japan National Traffic Safety and Environment Laboratory

Tokyo, Japan

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Matsui Y.,Japan National Traffic Safety and Environment Laboratory | Hitosugi M.,Dokkyo Medical University | Takahashi K.,Japan National Traffic Safety and Environment Laboratory | Doi T.,Ibaraki Christian University
Traffic Injury Prevention | Year: 2013

Objective: To reduce the severity of injuries and the number of pedestrian deaths in traffic accidents, active safety devices providing pedestrian detection are considered effective countermeasures. The features of car-to-pedestrian collisions need to be known in detail to develop such safety devices.Methods: Because information on real-world accidents is limited, this study investigated near-miss situations captured by drive recorders installed in passenger cars. We showed similarities of the contact situation between near-miss incidents and real-world fatal pedestrian accidents in Japan. We analyzed the near-miss incident data via video capturing pedestrians crossing the road in front of forward-moving cars. Using a video frame captured by a drive recorder, the time to collision (TTC) was calculated from the car velocity and the distance between the car and pedestrian at the moment that the pedestrian initially appeared.Results: The average TTC in the cases where pedestrians were not using a pedestrian crossing was shorter than that in the cases where pedestrians were using a pedestrian crossing. The average TTC in the cases where pedestrians emerged from behind obstructions was shorter than that in the cases where drivers had unobstructed views of the pedestrians.Conclusions: We propose that the specifications of the safety device for pedestrian detection and automatic braking should reflect the severe approach situation for a pedestrian and car including the TTC observed for near-miss incidents. © 2013 Copyright Taylor and Francis Group, LLC.


Goto Y.,Japan National Traffic Safety and Environment Laboratory
SAE Technical Papers | Year: 2013

As alternatives to heavy-duty vehicles, this project seeks to promote the development of Next-Generation EFVs, which will present a solution to the severe air pollution problem particularly in big cities, and drastically improve exhaust gas emissions and reduce carbon dioxide emissions in order to lessen the contribution to global warming. Ministry of Land, Infrastructure, Transport and Tourism (MLIT) started the Next-Generation Environmentally Friendly Vehicles Development and Commercialization Project in 2002. MLIT at that time entrusted this project to National Traffic Safety and Environment Laboratory (NTSEL). NTSEL as a core research organization organized a cooperative system with automobile manufacturers, suppliers, universities, academic experts, that is to say, industry-academic-government and launched the development activities. In 1st Stage (2002-2004), several target vehicles were developed such as, Dimethyl Ether (DME) Truck, IPS Hybrid Bus, Super Clean Diesel (SCD) Engine, and Compressed Natural Gas (CNG) Truck. In 2nd Stage (2005-2010), NTSEL applied following approaches; I. Commercialization of developed Next-Generation EFVs (Verification test) and II. Development and Promotion of New Next-Generation EFVs. Activities in NTSEL for the approach I and II are explained below; I. Commercialization of developed Next-Generation EFVs (Verification test) Dimethyl Ether (DME) Truck, IPS Hybrid Bus, Super Clean Diesel Engine, CNG Truck, II. Development and Promotion of New Next-Generation EFVs LNG (Liquefied Natural Gas) truck, FTD (GTL) (Fischer Tropsh Diesel (Gas to Liquid)) truck, Hydrogen engine. In 3rd Stage (2011-2014), this project focused on heavy duty vehicles in the transportation sector due to their high emission of CO2, for achievement of the Japanese mid-term target of 25% GHG emission reduction by 2020. NTSEL has promoted technology development in cooperation with automobile manufactures and has prepared for setting up a required standard in order to achieve the early realization of innovative technologies for low carbon and reduction of exhaust emission. As the Next-Generation environmental technology in heavy duty vehicles, NTSEL planned to deal with Electric/Plug-in Hybrid Truck in response to light/medium duty truck, High-efficient Hybrid Truck and Next-Generation Bio Diesel Engine in response to heavy duty truck, and High-performance Electric Route Bus in response to route bus. Activities of 3rd Stage in this project will be introduced. Copyright © 2013 SAE International.


Yamada H.,Japan National Traffic Safety and Environment Laboratory
Science of the Total Environment | Year: 2013

The features of evaporative emissions from gasoline vehicles were examined. One potential source of evaporative emissions is mainly the so-called sigh of a fuel tank, which is a function of the daily temperature change and the volume not occupied by fuel. A theoretical equation was proposed for estimating the fuel vapor generation. It reproduced observed features well but underestimated the absolute values obtained in the experimental results. The widely used semi-empirical Reddy equation overestimates the results. The performance of a carbon canister was also evaluated. More than 95% of fuel vapor generation was trapped by the carbon canister. However, the canister worked for only one day because it adsorbed more VOC than that contained in the sigh alone. To estimate the evaporative emissions in the real world, the fuel tank temperature change while a car was parked in an outside car park was monitored and was found to be almost the same as the change in ambient air temperature; no other weather conditions had any effect. According to the findings in this study and data on frequency of car use, the annual amount of evaporative emissions from gasoline vehicles in Japan was estimated to be 4.6% of the total VOC emissions in Japan, making it the 6th-highest source of VOC. © 2013 Elsevier B.V.


Matsui Y.,Japan National Traffic Safety and Environment Laboratory
Stapp car crash journal | Year: 2011

The number of traffic deaths in Japan was 4,863 in 2010. Pedestrians account for the highest number (1,714, 35%), and vehicle occupants the second highest (1,602, 33%). Pedestrian protection is a key countermeasure to reduce casualties in traffic accidents. A striking vehicle's impact velocity could be considered a parameter influencing the severity of injury and possibility of death in pedestrian crashes. A collision damage mitigation braking system (CDMBS) using a sensor to detect pedestrians could be effective for reducing the vehicle/pedestrian impact velocity. Currently in Japan, cars equipped with the CDMBS also have vision sensors such as a stereo camera for pedestrian detection. However, the ability of vision sensors in production cars to properly detect pedestrians has not yet been established. The effect of reducing impact velocity on the pedestrian injury risk has also not been determined. The first objective of this study is to evaluate the performance of the CDMBS in detecting pedestrians when it is installed in production cars. The second objective of this study is to evaluate the effect of reducing impact velocity on mitigating pedestrian injury. Firstly, impact experiments were performed using a car with the CDMBS in which the car collided with a pedestrian surrogate. In these tests, the velocity was chosen for the various test runs to be 20, 40 and 60 km/h, respectively, which were based on the velocity distribution in real-world pedestrian crashes. The results indicated that the impact velocity reduction ranged approximately from 10 to 15 km/h at the standing location of a pedestrian surrogate at both daytime and nighttime lighting conditions. These results show that the system has the potential to reduce pedestrian casualties from car-to-pedestrian contacts. Secondly, finite-element analyses were performed simulating vehicle-to- pedestrian impacts with the THUMS pedestrian models. The vehicle models selected for the study included a medium sedan, a minicar, and an SUV. Since head and chest injuries are the most typical causes of pedestrian deaths in car-to-pedestrian accidents, the risk of head and chest injuries was calculated when the impact velocity was reduced from 50 km/h to 40 km/h, 30 km/h, and 20 km/h. The results revealed that an impact velocity reduction of 10 km/h mitigated severe pedestrian injury at impact velocities greater than or equal to 40 km/h. Specifically, a significant effect was observed in collisions with the medium sedan and SUV. In Japan, the CDMBS has just started to be installed in medium sedans. The pedestrian injury mitigation will be greatly improved if the system can be applied to various types of vehicles including SUVs in the future.


Matsui Y.,Japan National Traffic Safety and Environment Laboratory
International Journal of Vehicle Safety | Year: 2011

Most pedestrian deaths in car-pedestrian accidents are due to head injuries. In 2005, the Japanese Ministry of Land, Infrastructure, Transport and Tourism (J-MLIT) began assessing the safety of bonnets impacting on pedestrians' heads using headform impactors with designated technical specifications. J-MLIT has used Type Approval Regulation Version 1 of headform impactors fitted with small un-damped accelerometers since 2005. Meanwhile, oil-damped accelerometers have been used by J-MLIT Type Approval Regulation Version 2 headform impactors since 2010. This paper summarises the development of pedestrian headform impactors used in headform impact tests in Japan and points to increasing safety levels. © 2011 Inderscience Enterprises Ltd.


Matsui Y.,Japan National Traffic Safety and Environment Laboratory
Stapp car crash journal | Year: 2010

The number of traffic deaths in Japan was 4,914 in 2009. Since the head was the most common site of injury in traffic accidents (2,302, 47%), traumatic brain injury causes the fatalities in these accidents. The aim of the present study was to quantify micro injuries in the animal brain for gaining insight and understanding of the human brain injury tolerance. Using porcine brain matter, in vitro stress relaxation experiments and in vivo impact experiments were conducted. In both experiments, the distribution of the damage ratio of the transverse to longitudinal length of cells, hereafter, referred to as an aspect ratio, in the brain matter under loading was examined. In the in vitro stress relaxation experiments, specimens were compressed vertically with a compression velocity of 1 mm/s, and the displacement was held for 140 sec when the compression strain reached the target strain. In the experiments, there were five categories of compression strain: 10, 20, 30, 40, and 50 percent. Regarding the aspect ratio of the cell body, it was 1.5 or less in a no-load condition. On the other hand, it was observed to be greater than 1.5 in the results from the experiments if the compression strain was 30% or more. The results from the experiments show that a compression strain between 20% and 30% corresponds to the threshold for the extremely deformed cell at the micro level. In the in vivo impact experiments, pigs in an unconscious state were exposed through craniotomy, and their exposed brains were hit with a ram at a low speed of 3.3 m/s and a high speed of 7.2 m/s, respectively. It was revealed that the number of cells in which the aspect ratio was greater than 1.5 increased if the impact is provided under the high speed. At the same time, the results indicated that cell deformation was dependent on the ram velocity in the brain matter. Thus, the compression strain on the entire brain from the direction of the force applied to the brain may be one criterion for assessment of brain damage.


Sumizawa H.,University of Tokyo | Yamada H.,Japan National Traffic Safety and Environment Laboratory | Tonokura K.,University of Tokyo
Applied Physics B: Lasers and Optics | Year: 2010

We report the accurate and precise measurement of nitric oxide (NO) in automotive exhaust gas by cavity ring-down spectroscopy (CRDS) using a thermoelectrically cooled, pulsed quantum cascade laser (QCL) as a light source. A mid-infrared QCL with a 5.26 μm wavelength was used to detect fundamental vibrational transitions of NO. An effective optical path length of 2.1 km was achieved in a 50 cm long cell using high-reflectivity mirrors. In combination with a particle filter and a membrane gas dryer, stable and sensitive measurement of NO in exhaust gas was achieved for more than 30 minutes with a time resolution of 1 s. The results of this work indicate that a laser based NO sensor can be used to measure NO in exhaust gas over a dynamic range of three orders of magnitude. © Springer-Verlag 2010.


Yamada H.,Japan National Traffic Safety and Environment Laboratory | Inomata S.,Japan National Institute of Environmental Studies | Tanimoto H.,Japan National Institute of Environmental Studies
Atmospheric Environment | Year: 2015

Breakthrough emissions that dominate diurnal evaporative emissions from gasoline vehicles were observed in continuous 3-day diurnal breathing loss (DBL) tests. These measurements were conducted on nine vehicles for the Japanese market. Two of these vehicles, made by US and European manufacturers, also meet regulations in their countries of origin. Four vehicles exhibited marked emissions caused by breakthrough emissions during the experimental period, all made by Japanese manufacturers. Using our experimental results, we estimate the total diurnal evaporative emissions from gasoline vehicles in Japan to be 32,792ty-1. The compositions of the breakthrough and permeation emissions were analyzed in real time using proton transfer reaction plus switchable reagent ion mass spectrometry to estimate the ozone formation potential for the evaporative emissions. The real-time measurements showed that the adsorption of hydrocarbons in a sealed housing evaporative determination unit can result in underestimation, when concentrations are only monitored before and after a DBL test. The composition analysis gave an estimated maximum incremental reactivity (MIR) 20% higher for the breakthrough emissions than for the gasoline that was tested, while the MIR for the permeation emissions was almost the same as the MIR for the fuel. Evaporative emissions from gasoline vehicles in Japan were found to contribute 4.2% to emissions from stationary sources using a mass-based estimate, or 6.1% of emissions from stationary sources using a MIR-based estimate. © 2015 Elsevier Ltd.


Matsui Y.,Japan National Traffic Safety and Environment Laboratory
Accident Analysis and Prevention | Year: 2014

This study investigated the characteristics of safety assessment results of front-area vehicle impact tests carried out using the Transport Research Laboratory (TRL) legform impactor and a flexible legform impactor (FLEX legform impactor). Different types of vehicles (sedan, sport utility vehicle, high-roof K-car, and light cargo van) were examined. The impact locations in the study were the center of the bumper and an extremely stiff structure of the bumper (i.e., in front of the side member) of each tested vehicle. The measured injury criteria were normalized by injury assessment reference values of each legform impactor. The test results for center and side-member impacts indicated that there were no significant differences in ligament injury assessments derived from the normalized knee ligament injury measures between the TRL legform impactor and the FLEX legform impactor. Evaluations made using the TRL legform impactor and the FLEX legform impactor are thus similar in the vehicle safety investigation for knee ligament injury. Vehicle-center impact test results revealed that the tibia fracture assessments derived from the normalized tibia fracture measures did not significantly differ between the TRL legform impactor and the FLEX legform impactor. However, for an impact against an extremely stiff structure, there was a difference in the tibia fracture assessment between the FLEX legform impactor and the TRL legform impactor owing to their different sensor types. © 2014 Elsevier Ltd. All rights reserved.


Matsui Y.,Japan National Traffic Safety and Environment Laboratory
International Journal of Crashworthiness | Year: 2014

The accelerometers in a conventional headform impactor are connected by cables to a data acquisition system placed on the ground. Recently, a portable small-sized data acquisition system was newly developed such that it could be installed inside a headform impactor. As a result, the headform impactor can work without a cable (an uncabled headform impactor). The present study showed that the specifications of uncabled child and adult pedestrian headform impactors meet the requirements of the Japanese Ministry of Land, Infrastructure, Transport and Tourism regulation. It was found that the resultant accelerations measured with the uncabled headform impactors were similar to those measured with currently used headform impactors in drop certification tests. Additionally, the head injury criterion measured with the uncabled headform impactors was remarkably similar to that measured with the cabled headform impactors in impact tests against bonnets of vehicles. Acceleration measured by uncabled headform impactors did not include any of the noise that is often observed in tests using cabled headform impactors. © 2014 Taylor & Francis.

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