Light-duty Trucks Research Articles

Use of Heteroscedastic Ordered Logit Model to Study Severity of Occupant Injury

A heteroscedastic ordered logit model was used to study the effects of various vehicle, environmental, roadway, and occupant characteristics on the severity of injuries sustained by vehicle occupants, conditional on the crash occurrence. As expected, the models found that heavier vehicles increased both a vehicle's crashworthiness and driver aggressiveness toward others. The models also found that if all passenger vehicles were to become 1,000 lb heavier, crash injury outcomes would not change dramatically. However, if all passenger cars were to become light-duty trucks (i.e., minivans, pickups, and sport utility vehicles) of the same weight, incapacitating injuries and fatalities were predicted to rise by 26% and 64%, respectively. Beyond weight and vehicle type, many other factors were controlled for as well. For example, older occupants and female occupants were more likely to experience injury and death, particularly when navigating curved roadway sections with higher speed limits.

Use of Heteroscedastic Ordered Logit Model to Study Severity of Occupant Injury: Distinguishing Effects of Vehicle Weight and Type

A heteroscedastic ordered logit model was used to study the effects of various vehicle, environmental, roadway, and occupant characteristics on the severity of injuries sustained by vehicle occupants, conditional on the crash occurrence. As expected, the models found that heavier vehicles increased both a vehicle's crashworthiness and driver aggressiveness toward others. The models also found that if all passenger vehicles were to become 1,000 lb heavier, crash injury outcomes would not change dramatically. However, if all passenger cars were to become light-duty trucks (i.e., minivans, pickups, and sport utility vehicles) of the same weight, incapacitating injuries and fatalities were predicted to rise by 26% and 64%, respectively. Beyond weight and vehicle type, many other factors were controlled for as well. For example, older occupants and female occupants were more likely to experience injury and death, particularly when navigating curved roadway sections with higher speed limits.

ＤＭＥディーゼルエンジンの機関特性と排出ガス特性

The increase in world population and the concomitant growth in world economy especially in Asia has created a necessity for additional energy which should not come at the cost of CO2 emission. The situation can be solved by making use of fuel produced from biomass. Dimethyl ether (DME) is a promising fuel in view of its clean emission and relatively low technical problems to commercialize it for light duty and heavy duty trucks. The emission of the latest 20 ton truck is within the post 2005 challenge regulation (namely, 09 regulation, NOx: 0.23g/kWh, PM: 0.01g/kwh) . The low boiling temperature of DME (-24.8C) necessitates the use of blend fuel for the safety of marine engines. The viscosity of the blend fuel (30% DME and 70% palm oil) is close to that of diesel fuel giving a similar performance as that of diesel fuel. The higher DME content in the blend fuel decreases the soot from the engine. The carbon deposit in the combustion chamber should be burned by the use of neat or high content of DME blended fuel.

3107 燃費向上を目指した小型ハイブリッドトラックの駆動系制御 : 人間-自動車系の特性を考慮した解析(運動制御,OS3 交通・物流システムのダイナミクスと制御,一般講演)

3107 燃費向上を目指した小型ハイブリッドトラックの駆動系制御 : 人間-自動車系の特性を考慮した解析(運動制御,OS3 交通・物流システムのダイナミクスと制御,一般講演)

Improvement on PM Reduction Using a Catalyst Based on V2O5/WO3/TiO2

Studies on the oxidation of diesel particulates characteristically showed that the particle number concentration for a particle size of about 30 nm can be reduced by more than 90% when the characteristics of the particulates are adapted to the oxidation potential of the catalyst employed. This corresponds to a total PM emission reduction of about 70% and demonstrates the high oxidation potential for other partial load operating points of a light-duty truck EURO 3 engine. It was found that the impact of modified engine adjustments on the particle contribution of smaller particles meets the technical requirements for an optimized reduction using an SCR catalyst based on V2O5/WO3/TiO2. Although the number concentration of particles with a size of <50 nm increases excessively, this results in a much higher efficiency of reduction of the particle number concentration by the catalyst, observed over the complete measurement range of the SMPS system used. The same result was also observed when EGR was used. The u...

Evaluating Speed Differences Between Cars, Light-Duty Trucks, and Vans for Emissions Modeling

The percentage of sport-utility vehicles, light-duty trucks, and passenger vans in the on-road light-duty fleet is steadily increasing. The implications for modeling emissions from on-road vehicles are significant since light-duty trucks produce, on average, more emissions than passenger cars. Although not frequently considered in calculating emission rates, differences in the average speeds of passenger cars, light-duty trucks, sport-utility vehicles, and passenger vans may influence emissions. This paper investigated whether the different classes of passenger vehicles operated differently on-road. Spot speed studies were used to determine differences in operating characteristics for three subgroups of the passenger car fleet. Results are presented for studies on freeways and arterials.

Measurements of nitrous oxide emissions from light-duty motor vehicles: a pilot study

Abstract Dynamometer testing in conjunction with high-resolution FTIR spectroscopy was used to measure exhaust emissions of nitrous oxide (N2O) from a fleet of 37 light-duty vehicles at the California Air Resources Board. Exhaust emissions were collected for two driving cycles: the Urban Dynamometer Driving Schedule and the Unified Cycle. The vehicles studied, including passenger cars, sport utility vehicles, and light-duty trucks, were a sub-sample of a fleet that represented California's in-use fleet. The highest correlation between the emissions of N2O and other vehicle-exhaust species was, as expected, between N2O and nitrogen oxides (r2=0.45). The previously reported impact of catalyst aging on N2O emissions could not be verified by our data. Type of catalyst, driving cycle, and vehicle were demonstrated to be the main factors determining the magnitude of N2O emissions from gasoline-powered light-duty vehicles. The average N2O emissions factor for the 37 vehicles tested was 20±4 mg km−1, with a factor of 50 difference between the lowest (2 mg km−1) and highest (100 mg km−1) N2O emissions. The average value for N2O/NOx emissions ratios was 0.095±0.035, with a factor of 14 difference between the lowest (0.01) and the highest (0.14) ratios.

CO2 emission benefit of diesel (versus gasoline) powered vehicles.

Concerns regarding global warming have increased the pressure on automobile manufacturers to decrease emissions of CO2 from vehicles. Diesel vehicles have higher fuel economy and lower CO2 emissions than their gasoline counterparts. Increased penetration of diesel powered vehicles into the market is a possible transition strategy toward a more sustainable transportation system. To facilitate discussions regarding the relative merits of diesel vehicles it is important to have a clear understanding of their CO2 emission benefits. Based on European diesel and gasoline certification data, this report quantifies such CO2 reduction opportunities for cars and light duty trucks in today's vehicles and those in the year 2015. Overall, on a well-to-wheels per vehicle per mile basis, the CO2 reduction opportunity for today's vehicles is approximately 24-33%. We anticipate that the gap between diesel and gasoline well-to-wheel vehicle CO2 emissions will decrease to approximately 14-27% by the year 2015.

Vehicle Dynamics Model for Estimating Maximum Light-Duty Vehicle Acceleration Levels

A vehicle dynamics model for predicting maximum light-duty vehicle accelerations for use within a microscopic traffic simulation environment is presented and validated. The research also constructs a database of unconstrained vehicle acceleration data for 13 light-duty vehicles and trucks. With the use of the field data, the proposed vehicle dynamics model is validated and compared with a number of state-of-the-art vehicle acceleration models, including the Searle model and the dual-regime, linear decay, and polynomial models. The advantages of the proposed model include its ability to predict vehicle behavior accurately with readily available input parameters and its flexibility in estimating acceleration rates of both large and small vehicles on varied types of terrain.

CNGセラミックスエンジン搭載ハイブリッドトラックの開発(J25-1 交通機械と進化するエネルギー技術,J25 交通機械と進化するエネルギー技術)

A CNG ceramics engine is developed for series-type hybrid light duty trucks. In this engine,by placing a throat valve at a throat of pre-chamber, compression-ignition was made possible without ignitions devices. This new combustion system that realizes both high thermal efficiency and low NOx emissions simultaneously was established. The fuel economy was improved up to 200% compared with the conventional diesel truck for M15 mode. Also,the D13 mode NOx exhausts emission was satisfied the ULEV of new shot-term regulation in Japan. This paper describes the performance of CNG ceramics engine.

Policy Watch: The Economics of Fuel Economy Standards

One of the most hotly contested of all energy policy issues involves Corporate Average Fuel Economy (or CAFE) standards for new cars and light-duty trucks. Tighter standards would reduce gasoline consumption, and hence both greenhouse gas emissions as well as this country's vulnerability to oil price shocks. But they would also increase the price of new vehicles, worsen traffic congestion and–depending on how they are phased in–possibly even reduce occupant safety. These effects are amenable to economic analysis, and we review the evidence to date bearing on this interesting and important question.

NO2/NO emissions of gasoline passenger cars and light-duty trucks with Euro-2 emission standard

The total amount, as well as the partitioning, of the NOx emissions of six gasoline passenger cars and 10 light-duty trucks, all of Euro-2 emission standard, was measured in this study. The measurements were carried out in the NEDC and FTP75 cycles, in the German “Bundesautobahnzyklus” (federal motorway cycle) and in Swiss real-world cycles. All the vehicles were provided by private owners and brought directly from the road to the chassis dynamometer. In order to obtain results which are as realistic as possible, no servicing was carried out. Depending on their mass, gasoline light-duty trucks of the Euro-2 emission standard have a legal HC+NOx limit which is 20–40% higher than for gasoline passenger cars of the same generation. The measurements show that light-duty trucks emit about eight times more NOx in Swiss real-world cycles compared to passenger cars. However, this cannot be due to the higher engine load alone; there have to be major differences in engine construction, engine tuning or in the layout of the exhaust gas aftertreatment system. It can be observed that the overall catalyst efficiencies of light-duty trucks are substantially lower than those of passenger cars. Apart from this difference in total NOx emissions, an interesting difference in the partitioning of NO and NO2 for passenger cars and light-duty trucks can be observed. On average, about 5.3 mass-percent of the NOx emissions from the measured passenger cars are emitted as NO2, without a clear effect on the velocity pattern driven. In contrast to the behaviour of passenger cars, the measured light-duty trucks show a strong dependence on the velocity pattern. They emit on average 18.4 mass-percent NO2, but this figure goes up to 38.3 percent for motorway driving. The measurements show that the NO2 mass fraction depends strongly on the absolute NOx emission level: the more NOx is emitted, the higher is the NO2 mass fraction.

Development of VT-Micro model for estimating hot stabilized light duty vehicle and truck emissions

The paper applies a framework for developing microscopic emission models (VT-Micro model version 2.0) for assessing the environmental impacts of transportation projects. The original VT-Micro model was developed using chassis dynamometer data on nine light duty vehicles. The VT-Micro model is expanded by including data from 60 light duty vehicles and trucks. Statistical clustering techniques are applied to group vehicles into homogenous categories. Specifically, classification and regression tree algorithms are utilized to classify the 60 vehicles into 5 LDV and 2 LDT categories. In addition, the framework accounts for temporal lags between vehicle operational variables and measured vehicle emissions. The VT-Micro model is validated by comparing against laboratory measurements with prediction errors within 17%.

A compact solid SCR system for NOx reduction in passenger cars and light duty trucks

Apart from the NOx adsorber catalyst, which has already been introduced in series for direct injection spark ignition engines, SCR technology represents an interesting solution for reducing NOx emissions from diesel vehicles. However, this requires a reductant such as urea as an additional operating medium. From today’s point of view, a wide-scale provision of the frequently discussed aqueous urea solution does not appear feasible in the short term. Therefore, the use of a solid reductant such as ammonium carbamate, with its considerably lower space requirements, presents an interesting alternative for individual motor vehicles. This article describes the solid SCR system developed by FEV Motorentechnik GmbH, as well as the first vehicle tests.

Analysis and prediction of traffic fatalities resulting from angle collisions including the effect of vehicles’ configuration and compatibility

Although the rapid growth in light truck vehicle (LTV) sales, including minivans, sports utility vehicles (SUVs), and light-duty trucks, has not been associated with an overall increase in collisions or traffic deaths in the US, there is a need for a research program to determine whether particular types of collisions have become more frequent or injurious because of the increase in the percent of LTVs in traffic. This paper presents an analysis of the effect of the increasing number of LTV registrations on fatal angle collision trends in the US. The analysis investigates the number of annual fatalities that result from angle collisions as well as collision configuration (car–car, car–LTV, LTV–car, and LTV–LTV). The analysis uses the Fatality Analysis Reporting System (FARS) crash databases covering the period 1975–2000. Results showed that death rates differ based on the collision configuration. Time series modeling results showed that fatalities in angle collisions will increase in the next 10 years, and that they are affected by the expected increase in the percentage of LTVs in traffic. Forecast showed that the total number of annual deaths is expected to reach 6300 deaths by the year 2010 (an increase of 12% over 2000). Analysis into the configuration of the collision indicated the seriousness of angle collisions involving an LTV striking a common passenger car (LTV–car). A time series model illustrated the significance of time lag and percent of LTVs in traffic on the increase of this type of fatal collisions. Forecasts from the time series model indicated a 32% increase in deaths due to this type of collisions in the next 10 years.

Modeling rear-end collisions including the role of driver’s visibility and light truck vehicles using a nested logit structure

This paper presents an analysis of the effect of the geometric incompatibility of light truck vehicles (LTV)—light-duty trucks, vans, and sport utility vehicles—on drivers’ visibility of other passenger cars involved in rear-end collisions. The geometric incompatibility arises from the fact that most LTVs ride higher and are wider than regular passenger cars. The objective of this paper is to explore the effect of the lead vehicle’s size on the rear-end crash configuration. Four rear-end crash configurations are defined based on the type of the two involved vehicles (lead and following vehicles). Nested logit models were calibrated to estimate the probabilities of the four rear-end crash configurations as a function of driver’s age, gender, vehicle type, vehicle maneuver, light conditions, driver’s visibility and speed. Results showed that driver’s visibility and inattention in the following (striker) vehicle have the largest effect on being involved in a rear-end collision of configuration CarTrk (a regular passenger car striking an LTV). Possibly, indicating a sight distance problem. A driver of a smaller car following an LTV, have a problem seeing the roadway beyond the LTV, and therefore would not be able to adjust his/her speed accordingly, increasing the probability of a rear-end collision. Also, the probability of a CarTrk rear-end crash increases in the case that the lead vehicle stops suddenly.

Microscopic Modeling of Vehicle Start Emissions

A microscopic framework for estimating instantaneous vehicle start emissions for light-duty vehicles and trucks is developed. The framework assumes a linear decay in instantaneous start emissions over a 200-s time horizon. The initial vehicle start emissions rate is computed by using the soak time function of the U.S. Environmental Protection Agency’s MOBILE6 model, assuming a 200-s decay time interval. The use of the MOBILE6 soak time function ensures that the microscopic procedures that are developed produce start emissions that are consistent with the MOBILE6 model. The validity of the framework was demonstrated using independent trips that involved cold-start and hot-start impacts with vehicle emissions estimated to within 10% of the test in-laboratory measurements.

Mobile-Source Emissions: Analysis of Spatial Variability in Vehicle Activity Patterns and Vehicle Fleet Distributions

Accurately estimating mobile-source emissions requires a good understanding of vehicle activity and the characteristics of the on-road vehicle fleet. Spatial variability in vehicle activity patterns and vehicle fleet composition can have significant effects on the overall emissions inventory. Simply determining total vehicle miles traveled is insufficient for emissions inventory calculations from the new-generation models of mobile-source emissions. Improvements in emissions-control technology over the past 20 years have led to large decreases in the emissions of light-duty cars and trucks, resulting in large variations in vehicle emissions depending on model year and technology type. In addition, research indicates that the accurate characterization of vehicle activity is necessary in conjunction with better spatial resolution of vehicle fleet characteristics because of the differing modal behavior of the vehicles within various vehicle and technology groups. Vehicle activity and vehicle fleet data were collected in the South Coast Air Basin in southern California. Vehicle activity was characterized primarily using a large second-by-second speed and acceleration data set collected from probe vehicles operated within the flow of traffic. In addition, three sets of vehicle fleet data were collected and used for spatial comparison. The results of the analysis show spatial and temporal differences in vehicle activity patterns and vehicle fleet characteristics; differences in speed and congestion affect the speed–acceleration profiles as well as associated emissions.

Comparison of Vehicle Exhaust Emissions from Modified Diesel Fuels

Three diesel fuels, one oil sand-derived (OSD) diesel serving as base fuel, one cetane-enhanced base fuel, and one oxygenate [diethylene glycol dimethyl ether (DEDM)]-blended base fuel, were tested for their emission characterizations in vehicle exhaust on a light-duty diesel truck that reflects the engine technology of the 1994 North American standard. Both the cetane-enhanced and the oxygenate-blended fuels were able to reduce regulated [CO, particulate matter (PM), total hydrocarbon (THC)] and nonregulated [polyaromatic hydrocarbons (PAHs), carbonyls, and other volatile organic chemicals] emissions, except for nitrogen oxides (NOx ), compared with the base fuel. Although burning a fuel that contains oxygen could conceivably yield more oxygenated compounds in emissions, the oxygenate-blended diesel fuel resulted in reduced emissions of formaldehyde along with hydrocarbons such as benzene, 1,3-butadiene, and PAHs. Reductions in nitro-PAH emissions have been observed in both the cetane-enhanced and oxygenated fuels. This further demonstrates the benefits of using a cetane enhancer and the oxygenated fuel component.

Configuration Analysis of Two-Vehicle Rear-End Crashes

Light truck vehicles (LTVs), including light-duty trucks, vans, minivans, and sport-utility vehicles, are generally larger than common passenger cars and are able to take on additional tasks. LTVs usually ride higher than other common passenger cars, which likely affects the visibility of passenger car drivers. The role of LTVs in rear-end crashes was investigated. The use of statistical models of unordered multiple categories was attempted, including multinomial logit (MNL), heteroscedastic extreme value (HEV), and bivariate probit (BVP) models. Four different rear-end crash configurations (lead and following vehicles) were defined on the basis of the type of the two vehicles involved (LTV or regular passenger car). General Estimates System (GES 2000) traffic crash data were used to calibrate the three suggested models (the MNL, HEV, and BVP models). Modeling results showed that there are sight distance and discomfort problems when a driver in a regular passenger car is driving behind an LTV. The probability of a rear-end crash involving a regular passenger car striking an LTV increases when the driver of the following vehicle is distracted. The analysis also illustrates that the probability of a regular car striking an LTV increases when the driver of the following vehicle has an obscured view.