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The primary purpose of the speed limit system is to enforce reasonable and safe speed. To reduce secondary problems such as accidents and queuing, Variable Speed Limits (VSL) has been suggested. In this paper VSL is used to better safety and traffic parameters. Traffic parameters including speed, queue length and stopping time have been pondering. For VLS, an optimization decision tree algorithm with the function of microscopic simulation was used. The results in case of sub saturated, saturated and supersaturated at a bottleneck are examined and compared with the Allaby logic tree. The results show that the proposed decision tree shows an improved performance in terms of safety and comfort along the highway. The VSL pilot project is part of the Road Safety Improvement Program included in Iran's road safety action plan that is in the research process in the BHRC Research Institute, Road and Housing & Urban Development Research that is planned for next 10-year Transportation safety view Plan. [ABSTRACT FROM AUTHOR]

Newly-constructed and reconstructed highway pavements under the effect of traffic loading and climatic severity deteriorate progressively and need preservation intervention after a certain number of years following their construction. In the literature, the term ‘rest period’ has been used to refer to the number of years that elapse between the construction completion to the application of first major repair activity. The rest period is a critical piece of information that agencies use to not only plan and budget for the first major repair activity but also to develop more confidently, their life-cycle activity schedules for life cycle costing, work programming, and long-term plans. However, the literature lacks established procedures for predicting rest periods on the basis of pavement performance thresholds. In the absence of such resources, highway agencies rely mostly on expert opinion for establishing the rest periods for their pavement sections. In addressing this issue, this paper presents a statistical methodology for establishing the rest periods for newly-constructed or reconstructed pavements. The methodology was demonstrated using empirical data from in-service pavements in a Midwestern State in the US. The paper’s results show that the rest periods of newlyconstructed and reconstructed highway pavements are significantly influenced by their functional class, surface material type, traffic loading level, and climate severity. [ABSTRACT FROM AUTHOR]

This paper is devoted to the problem of reducing vehicle energy consumption. The authors consider the optimisation of highway driving cycle a way to use the kinetic energy of a car more effectively at various road conditions. The model of a vehicle driving control at the highway which consists of elementary cycles, such as accelerating, free rolling and deceleration under forces of external resistance, was designed. Braking, as an energy dissipation regime, was not included. The influence of the various longitudinal profiles of the road was taken into consideration and included in the model. Ways to use the results of monitoring road and traffic conditions are presented. The method of non-linear programming is used to design the optimal vehicle control function and phase trajectory. The results are presented by improved typical driving cycles that present energy saving as a subject of choice at a specified schedule. [ABSTRACT FROM AUTHOR]

Three different type of double road trains are selected as simulation model, which is commonly used in developed countries and regions in order to improve the efficiency of road transport and the development of China's logistics industry. The passing ability simulation model of double road train is established based on Auto Turn, and China's current longest tractor-semitrailer is used as a comparison. Simulation models of highway ramp, first class highway and second class highway are established according to the requirement of JTG D20-2006 ‘Design Specification for Highway Alignment’. Adaptability of double road train and highway structure parameter is researched by analyzing different types of double road train turn left, turn right and turn around on the road. The type of double road train which can meet China's standards is recommended. The result can promote the application of double road train and give some advice for improving passing ability. [ABSTRACT FROM AUTHOR]

Many studies have documented the merits and problems of nighttime work for highway construction. Most of these studies have examined the safety of the construction site for workers or the traveling public. Illumination standards, sign requirements, and crash rate data have been studied to determine whether crash rates increase during nighttime hours, and the reasons for these crashes. Few studies have addressed either the effects on cost or productivity that nighttime construction has on a project. This study used hard bid unit prices to focus on the effect that performing certain construction activities at night has on cost and productivity. Specifically, the study assumes that a contractor's bid amount reflects expected relative project productivity and answers the question, 'What impact, if any, does night work have on construction productivity and therefore bid price?' This is the first paper to answer both questions as related. Among the results was the fact that for the most part, the owner would have saved millions of dollars by allowing the contractor the option of working at night or during the day, though some items were bid lowest if the contract allowed for night work only. [ABSTRACT FROM AUTHOR]

This work presents a fuzzy logic-based highway on-ramp control (HORC) approach that works by controlling the traffic lights at the on-ramp to facilitate the flow of traffic onto the highway. The proposed HORC comprises a fuzzy logic system and a decision-making model. The former determines the switching probability of the traffic light, while the latter makes the decision concerning the switching of the traffic light. The HORC requires only the velocities and the difference of velocities of the vehicles that are entering the highway. Simulation results indicate that the proposed HORC outperforms pre-timed ramp control. [ABSTRACT FROM PUBLISHER]

Abstract: We propose a modification of the widely known Benjamin–Johnson–Hui (BJH) cellular automaton model for single-lane traffic simulation. In particular, our model includes a ‘slow-to-stop’ rule that exhibits more realistic microscopic driver behaviour than the BJH model. We present some statistics related to fuel economy and pollution generation and show that our model differs greatly in these measures. We give concise results based on extensive simulations using our system. [ABSTRACT FROM AUTHOR]

We investigate connectivity in the ad hoc network formed between vehicles that move on a typical highway. We use a common model in vehicular traffic theory in which a fixed point on the highway sees cars passing it that are separated by times with an exponentially distributed duration. We obtain the distribution of the distances between the cars, which allows us to use techniques from queuing theory to study connectivity. We obtain the Laplace transform of the probability distribution of the connectivity distance, explicit expressions for the expected connectivity distance, and the probability distribution and expectation of the number of cars in a platoon. Then, we conduct extensive simulation studies to evaluate the obtained result. The analytical model that we present is able to describe the effects of various system parameters, including road traffic parameters (i.e., speed distribution and traffic flow) and the transmission range of vehicles, on the connectivity. To more precisely study the effect of speed on connectivity, we provide bounds obtained using stochastic ordering techniques. Our approach is based on the work of Miorandi and Altman, which transformed the problem of connectivity distance distribution into that of the distribution of the busy period of an equivalent infinite server queue. We use our analytical results, along with common road traffic statistical data, to understand connectivity in vehicular ad hoc networks. [ABSTRACT FROM AUTHOR]

Previous studies suggest that eastern chipmunks (Tamias striatus) avoid roads, but it is unclear whether vehicle traffic plays a role in this avoidance. The purpose of this study was to determine whether road avoidance in chipmunks increases with traffic. We tracked the movements of 68 chipmunks released near roads with widely varying volumes of traffic. Our results suggest that chipmunks responded to changes in traffic volume only in the preliminary stages of their movement pathways. Apart from this initial response, we found that road avoidance was independent of traffic, with evidence that chipmunks avoided both the roadside verge and the road surface. Because avoidance of roads was independent of traffic, effects of roads on populations of chipmunks may be manifest more as population subdivision than as direct mortality. [ABSTRACT FROM AUTHOR]