Analytical and grid-free solutions to the Lighthill-Whitham-Richards traffic flow model

In this article, we propose a computational method for solving the Lighthill-Whitham-Richards (LWR) partial differential equation (PDE) semi-analytically for arbitrary piecewise-constant initial and boundary conditions, and for arbitrary concave fundamental diagrams. With these assumptions, we show that the solution to the LWR PDE at any location and time can be computed exactly and semi-analytically for a very low computational cost using the cumulative number of vehicles formulation of the problem. We implement the proposed computational method on a representative traffic flow scenario to illustrate the exactness of the analytical solution. We also show that the proposed scheme can handle more complex scenarios including traffic lights or moving bottlenecks. The computational cost of the method is very favorable, and is compared with existing algorithms. A toolbox implementation available for public download is briefly described, and posted at http://traffic.berkeley.edu/project/downloads/lwrsolver.     

What will autonomous trucking do to U.S. trade flows? Application of the random-utility-based multi-regional input–output model

Transportation - This study anticipates changes in U.S. highway and rail trade patterns following widespread availability of self-driving or autonomous trucks (Atrucks). It uses a...     

Introducing advanced electronic driver support systems: An exploration of market and technological uncertainties

R&D in the field of driver support systems is increasingly paid attention to. These systems can contribute significantly to public traffic goals. However, there is much uncertainty about future technology developments, market introduction, and impacts on driver and traffic behaviour. An international Delphi study collecting expert opinions on these issues is partly described here. The Delphi study was organized in three rounds. Opinions of 50 experts from the USA, Japan and Europe were collected. The paper is limited to market introduction, and technological and driver-behavioural barriers. The main conclusion is that future developments are less obvious than often assumed.     

Experimental study comparing racecar aerodynamic downforce-generating devices using scale model NASCAR COT

The performance and safety of the rear wing and spoiler employed on the National Association of Stock Car Auto Racing (NASCAR) COT (car of tomorrow) racecar are experimentally studied using 10 % scale models in a water channel. Particle image velocimetry is used to qualitatively examine the differences in flow structures between the two downforce-generating devices under 0 and 180-degree yaw cases. The latter is important due to an issue with the COT flipping into the air when at extreme yaw (i.e. during a crash). At zero yaw, it is observed that smaller length scales of the flow structures in the wake of the wing compared to those in the wake of the spoiler, provide more predictable handling for racecars in close proximity and may allow more safe and competitive racing. At 180-degree yaw, it is observed that wake-structure interactions may not allow proper operation of anti-flipping devices (roof flaps) on the winged car. In the extreme yaw case, local flow scales are examined and show much stronger Reynolds number (Re) dependence for the wing than the spoiler.     

Modeling and ratio control of an electromechanical continuously variable transmission

A new type of electromechanical continuously variable transmission (EMCVT) was investigated. The EMCVT uses a direct current (DC) motor to push the driving pulley, which in turn changes the transmission ratio without a hydraulic system. This paper introduces the principle of the EMCVT and establishes a dynamic ratio control model. Ratio control strategies using both position and speed closed-loop control are proposed. Simulation results show that the simulation ratio curves of the EMCVT follow pre-designed ratios well for ramp and sine curves. Control software is based on MATLAB/Simulink/Stateflow and MotoHawk platforms. A prototype vehicle equipped with an EMCVT has been developed. Vehicle test results show that the control performance of the EMCVT satisfies the requirements of vehicle operation. The effectiveness of the EMCVT ratio control strategy proposed in this paper is validated with test data for the prototype vehicle.     

Topological analysis of powertrains for refuse-collecting vehicles based on real routes–Part II: Hybrid electric powertrain

In this two-part paper, a topological analysis of powertrains for refuse-collecting vehicles (RCVs) based on simulation of different architectures (internal combustion engine, hybrid electric, and hybrid hydraulic) on real routes is proposed. In this second part, three different hybrid electric powertrain architectures are proposed and modeled. These architectures are based on the use of fuel cells, ultracapacitors, and batteries. A calculation engine, which is specifically designed to estimate energy consumption, respecting the original performance as the original internal combustion engine (ICE), is presented and used for simulations and component sizing. Finally, the overall performance of the different architectures (hybrid hydraulic, taken from the first paper part, and hybrid electric, estimated in this second part) and control strategies are summarized in a fuel and energy consumption table. Based on this table, an analysis of the different architecture performance results is carried out. From this analysis, a technological evolution of these vehicles in the medium- and long terms is proposed.     

Capacity Building for Integrated Coastal Management in Asia-Pacific: The Case for Case Studies

Development of awareness and capacity is a central component to the delivery of ICM and spans from local communities to national-level politicians. Education and training activities associated with ICM must be extremely varied to match both the existing capacity and role that the stakeholders play within the process of ICM. Consequently, there cannot be considered any effective “generic” ICM training; training must be tailored to match the requirements of target groups. The transfer and uptake of good-practice thus becomes an important aspect of quality enhancement in ICM capacity development. Six case studies from the Asia-Pacific region are presented that show diverse and innovative examples of good practice. A comparative analysis of these case studies is carried out in terms of institutional level of impact. In addition a generic systems-based evaluation framework is used to determine the extent to which the training impacts upon ICM implementation indicators. It is concluded that the exchange, transfer, and translation to local conditions of appropriate good practice in ICM capacity development can be an important element in enhancing the impact of ICM programs on the coastal environments and societies. Furthermore, there appears to be a positive link between the involvement of national/state/regional stakeholders in capacity-building initiatives and impacting a wider variety of indicators of ICM delivery.     

The Brazilian National Plan for Coastal Management (PNGC)

The article is divided into three clearly defined sections. The first outlines the Brazilian National Coastal Zone Management Plan. The second offers a critical assessment of its introduction. To conclude, some general considerations are made. In this way, the author aims to achieve two objectives: to disseminate the aforementioned plan and offer a critical opinion of it.     

Forecasting petrol demand and assessing the impact of selective strategies to reduce fuel consumption

Abstract

The use of fossil fuels in transportation is an important topic as a result of growing concerns over global warming. Automobile petrol demand has been of particular interest to researchers and policy-makers, given that the automobile is a major contributor to the enhanced greenhouse effect. This paper forecasts Australia's automobile petrol demand up to the year 2020 based on the best performing forecasting model selected out of eight models. In order to establish ways to reduce the demand for petrol, and the consequent by-product of reducing the amount of greenhouse gas emissions, we have estimated the impact on CO₂ for several potential policy instruments, using Transportation and Environment Strategy Impact Simulator (an integrated transport, land use and environmental strategy impact simulation programme). We find that a carbon tax of AU$0.50/kg can reduce automobile kilometres by 5.9%, resulting in reduced demand for petrol and a reduction in CO₂ of 1.5%.     

Forecasting automobile petrol demand in Australia: An evaluation of empirical models

Transport fuel consumption and its determinants have received a great deal of attention since the early 1970s. In the literature, different types of modelling methods have been used to estimate petrol demand, each having methodological strengths and weaknesses. This paper is motivated by an ongoing need to review the effectiveness of empirical fuel demand forecasting models, with a focus on theoretical as well as practical considerations in the model-building processes of different model forms. We consider a linear trend model, a quadratic trend model, an exponential trend model, a single exponential smoothing model, Holt’s linear model, Holt–Winters’ model, a partial adjustment model (PAM), and an autoregressive integrated moving average (ARIMA) model. More importantly, the study identifies the difference between forecasts and actual observations of petrol demand in order to identify forecasting accuracy. Given the identified best-forecasting model, Australia’s automobile petrol demand from 2007 through to 2020 is presented under the “business-as-usual” scenario.