A study of factors influencing the severity of road crashes involving drunk drivers and non drunk drivers

In this study, an attempt has been made to develop Multinomial Logit (MNL) model by analysing the drunken and non drunken drivers involved in road crashes on Indian highways. Multinomial Logit model has been deployed to assess the influence of various parameters like vehicular, environment and geometric factors on the set of drivers who were found to be drunk at the time of getting involved in the road crash and those who were not under the influence of alcohol at the time of meeting with the road crash. The total economic cost of road crashes in the case of non-drunk driver road crash is Rs. 1046.27 million whereas in the case of drunk driver road crashes it is estimated to be Rs. 204.50 million. Further, it can be observed that economic cost of drunk driver road crashes is varying from 13 to 19 % across different types of road crashes.     

冲压荷载下水泥路面土基的变形及应力分析

通过建立有限元模型,采用瞬态动力学加载方法,模拟冲击压路机破裂稳固旧水泥混凝土路面的冲压效果,探讨冲压荷载作用下土基中的应力传递规律和沉降变形．结果表明：在土基顶面以下5 m深度处由冲压荷载引起的土基竖向应力和位移均接近于0,冲压荷载的影响深度不超过5 m;冲压荷载作用下路基的工作区为2．25 m深度范围内,埋深超过2．25 m的构造物理论上不受冲压荷载的影响．     

Optimal stop spacing and headway of congested transit system considering realistic wait times

Abstract

This paper revisits the classical transit scheduling problem and investigates the relationship between stop spacing and headway, considering realistic wait time and operable transit capacity. Headway and stop spacing are important determinants for planning a transit system, which influence the service level as well as the cost of operation. A mathematical model is developed, and the objective function is user travel time which is minimized by the optimized stop spacing and headway, subject to the constraints of operable fleet size and route capacity. Optimal stop spacing and headway solutions are obtained in a numerical example. Sensitivity analysis is conducted, and the effect of model parameters on user travel time is explored.     

A three-stage least squares approach to the analysis of airline strategies for aircraft size and airline frequency on the north Atlantic: an airline case study

In response to increasing demand, airlines may increase capacity by increasing the frequency of flights or they may choose to increase aircraft size. This may yield operating cost economies. If the airports they operate from are capacity constrained, they will be limited in the extent that they can change frequency which will limit their ability to compete with the number of frequencies offered. This article focuses on this trade-off and pays particular attention to the practices of a specific airline. Conclusions are offered on the impact of inter alia competition, changes in aircraft technology, 9/11 and the impact of slot constraints. It appears that changes in size are more important than frequency, which is consistent with the presence of slot constraints and there is a significant impact of competition. As the concentration of carriers increases, so aircraft size falls. 9/11 also has a significant impact on traffic whereas the introduction of the Boeing 777, as an illustration of a change in technology, does not.     

A Microscopic Simulation Model for Incident Modeling in Urban Networks

Abstract

This paper reviews the main modules of an integrated system for incident management in real-time, -sim. A core to such a system is a microscopic simulator with extended abilities to model the temporal and spatial evolution of specified non-recurrent traffic conditions. The paper reviews the mathematical formulation of the car-following and lane-changing modules. The model is validated using a simulation-based approach. Concluding comments on the general validation process of the model are provided. The paper finally presents a sample of the accident patterns replicated by the model together with their implications for real world validation.     

Optimization of Fare Structure and Service Frequency for Maximum Profitability of Transit Systems

Abstract

Providing efficient public transportation has been recognized as a potential way of alleviating congestion, improving mobility, mitigating air pollution, and reducing energy consumption. Many people use public transportation systems for their daily commute, while others use different transportation modes (e.g. cars, taxis, carpools, etc.). Inexpensive fares with good transit service encourages ridership, and the resulting revenue may be used to provide better service. Optimization of transit service frequency and its associated fare structure is desirable in order to increase revenue at reasonable transit operating expenditure. The objective of the study reported here is to maximize profit subject to service capacity constraint, while elastic demand is considered. The solution methodology is developed and applied to solve the profit maximization problem in a case study based on Newark, NJ, USA. Numerical results, including optimal solutions and sensitivity analyses, are presented. It is found that an optimal temporal headway and differential fare structure that maximizes total profit for the studied subway system can be efficiently solved.     

Valuation of environmental externalities: from theory to decision‐making

Valuation of externalities is a condition for correct investment and pricing decisions in transport. This paper provides a brief survey of the main studies achieved in OECD countries in order to get these valuations. Numerical values for the average social cost of transport are presented. The procedures according to which environment is taken into account in France and Italy are analyzed, and the importance of valuation in these procedures is assessed. Finally, prospects for further research and new developments are expressed.     

Impact technique for measuring global dynamic stiffness of engine mounts

Engine mounts are used for engine vibration isolation. The dynamic performance of the mount depends on the orientation. Measurements of the dynamic properties of engine mounts are usually performed in the axial direction because of the problem related to actuator loading direction and set up costs. Impact technique is developed here to measure the dynamic driving point stiffness and driving point shear stiffness of engine mount in a single setup. The compressive and shear frequency-dependent stiffnesses are obtained in the vertical orientation. A transformation matrix is used to calculate the frequency-dependent stiffnesses and loss factors in other orientations. Three different designs of engine mounts are used to verify the accuracy of the transformation model. The correlation coefficient between calculation and measurement results show R²≥ 0.995 along the X- and Y-axes. For the Z-axis, mounts B and C showed R²≥ 0.95 and mount A 0.687 ≤ R²≤ 0.791.     

Methodology for bus structure torsion stiffness and natural vibration frequency prediction based on a dimensional analysis approach

Engineering bus design requires testing of bus structures prototypes in order to guarantee a certain level of strength and an appropriate static and dynamic behavior of the bus superstructure when exposed to road loads. However, experimental testing of real bus structures is very expensive as it requires expensive resources and space. If testing is done on a scale bus model the previous required expenses are considerably reduced. Therefore, a novel methodology based on dimensional analysis applied to bus structure prediction to evaluate the bus structure static and dynamic performance is proposed. The static performance is evaluated attending to torsion stiffness and the dynamic in terms of the natural vibration frequencies and rollover threshold. A scale bus has been manufactured and dimensionless parameters have been defined in order to project the results obtained in the scale bus model to a larger model. Validation of the proposed methodology has been carried out under experimental and finite element analysis.     

某型舰炮武器模拟训练系统设计

以军事需求为依据,提出了基于HLA的某型舰炮武器模拟训练系统的功能性能需求,描述了运行体系和支持条件等仿真环境,设计了软硬件实施方案和系统运行流程.实践证明该方案设计合理,可操作性强,能够达到武器系统仿真要求.