Estimating traffic demand risk – A multiscale analysis

This paper proposes a novel method for estimating the traffic demand risk associated with transportation. Using mathematical properties of wavelets, we develop a statistical measure of traffic demand sensitivity with respect to GDP. This measure can be adapted in a flexible way to capture risk levels relevant for different investment horizons. We demonstrate the timescale decomposition of risk with Swedish traffic demand data for 1950–2005. In general, rail transport shows a stronger co-movement with GDP than road transport. Moreover, we examine the volatility exhibited by traffic demand. Our findings suggest that rail investments are more risky than road investments. Since the findings can be used for optimal investment timing and for choice between public investment alternatives, they are deemed important for public policy in general.     

Estimation of road profile variability from measured vehicle responses

When assessing the statistical variability of fatigue loads acting throughout the life of a vehicle, the question of the variability of road roughness naturally arises, as both quantities are strongly related. For car manufacturers, gathering information on the environment in which vehicles evolve is a long and costly but necessary process to adapt their products to durability requirements. In the present paper, a data processing algorithm is proposed in order to estimate the road profiles covered by a given vehicle, from the dynamic responses measured on this vehicle. The algorithm based on Kalman filtering theory aims at solving a so-called inverse problem, in a stochastic framework. It is validated using experimental data obtained from simulations and real measurements. The proposed method is subsequently applied to extract valuable statistical information on road roughness from an existing load characterisation campaign carried out by Renault within one of its markets.     

Modeling multi-unit vehicle dynamics for low-speed path-following assessment off-highway

This paper proposes a non-linear dynamics model for articulated vehicles. This model is able to capture common low-speed behaviours of any articulated vehicles off-highway, such as operating for a corner or roundabout on a cambered or slippery surface. It can be used to assess the low-speed manoeuvrability of articulated vehicles under such manoeuvres and conditions. The vehicle model was validated by comparing its path tracking performance to that of the field tests.     

Vehicle sensor data-based analysis on the driving style differences between operating indoor simulator and on-road instrumented vehicle

Abstract

Indoor simulator and on-road instrumented vehicle are the most popular ways to analyze driving behaviors by using collected Vehicle Sensor Data (VSD). However, for a same driver, the driving performance could be different in the real world and in the simulated world. Even though many studies have been conducted to discover the differences of driving behaviors in these two circumstances, little research has focused on analyzing the differences in driving style, which can provide more integrated knowledge of a driver from the natural structure, stimulus–response mechanism, of driving behaviors. Therefore, in this paper, the driving styles in both the real world and the simulated world are extracted by implementing the nonnegative matrix factorization method on the collected VSD data. Through this analysis, the driving style differences can be quantitatively described and discussed in detail. It is found that the drivers tend to be more unstable and sometimes aggressive when driving the simulator and the deviation in the perception of temporal gap in two circumstances is also discovered. The research findings are particularly valuable to calibrate the driving simulator and construct more reliable driving behavior models.     

Policy considerations for wetland wastewater treatment in the coastal zone: A case study for Louisiana

Two major environmental problems currently affecting the Louisiana coastal zone are a high rate of wetland loss and high levels of surface water pollution. The application of secondarily treated wastewater to wetlands can be a means of dealing with both of these problems. The benefits of wetland wastewater treatment include improved surface water quality, increased accretion rates to balance a high relative water level rise due mainly to subsidence, improved plant productivity and habitat quality, and decreased capital outlays for conventional engineering treatment systems. Wetland treatment systems can, therefore, be designed and operated to restore deteriorating wetlands. Hydrologically altered wetlands, which are common in the Louisiana coastal zone, are appropriate for receiving municipal and some types of industrial effluent. While the U.S. Environmental Protection Agency has determined wetland wastewater treatment is effective in treating municipal effluent, it has discouraged the use of natural wetlands for this purpose. At the same time, funds are being used for the construction of artificial wetlands to treat municipal effluent. In the Louisiana coastal zone, however, wetlands are deteriorating and disappearing due to hydrological alteration and a high rate of relative sea level rise. If no action is taken, these trends will continue. Effluent discharge to existing wetlands should be incorporated into a comprehensive management plan designed to increase sediment and nutrient input into subsiding wetlands in the Louisiana coastal zone, improve water quality, and result in more economical waste‐water treatment. The authors believe that the Louisiana example serves as a model for other coastal areas especially in light of projections of accelerated sea level rise.     

Competition and ownership in land passenger transport: the fourth international conference — Part 2

In the rail industry worldwide, there has been a search for new solutions, including restructuring, corporatization, and outright privatization, but the complexity of the rail industry offers special problems. In the Workshop we looked in detail at the British, Swedish, German, Australian (New South Wales) and New Zealand experiences, as well as considering more general issues such as cost structures, vertical separation and competitive tendering. Whilst it was agreed that some developments, such as greater contracting out, were clearly beneficial, other developments such as the separation of infrastructure from operations remained of uncertain value until the issues of efficient pricing and slot allocation were resolved.     

A Study in Port Planning: The Example of Mina Zayed

The correct number of berths that a port should provide is solved by a model which minimizes the total port usage cost in terms of the costs of berth provision and the costs accruing to ships from time spent in the port. This model is then applied to Mina Zayed in the Arabian Gulf as an aid to future planning, and from different sets of cargo forecasts an optimal stategy is derived using a game-theoretic approach.     

Remoteness and accessibility in the vulnerability analysis of regional road networks

This paper considers the development of a method for network vulnerability analysis which considers the socio-economic impacts of network degradation and seeks to determine the most critical locations in the network. The method compares the levels of remoteness (or its inverse, accessibility) of localities within the study region, on the basis of the impacts of degradation of the road network on a recognised accessibility/remoteness index that can be applied to each and every location within the region. It thus extends the earlier work on accessibility-based vulnerability analysis which was limited to assessment of impacts on selected nodes in a network. The new method allows study of impacts on both specified locations (which do not have to be represented as network nodes) and the region as a whole. The accessibility/remoteness index is defined so that an accessibility surface can be calculated for the region, and the volume under this surface provides an overall measure of accessibility. Changes in the volume under different network states thus reflect the overall impacts. The method is applied to a rural region in south east Australia.     

The impact of job assignment rules for straddle carriers on the throughput of container terminals

Straddle carriers represent a critical resource in the handling of containers within a container terminal. It is essential that they are deployed in an as efficient manner as possible. The research presented in this paper is motivated by the need to critically evaluate job assignment rules for straddle carriers that operate in a multiple straddle environment. This is achieved by developing a discrete event simulation model using industrial simulation software to model a container terminal located in Melbourne, Australia. The model accounts for variables such as the number of straddle carriers needed, the speed of straddle carriers, the arrival rate of trucks, and the job assignment rule. A principal finding of the study is that increasing the number of straddles in the present set‐up from 6 to 7 has a negligible effect on daily throughput. However, an increase in the number of straddles to 7 is expected to have a profound effect on reducing the average waiting time of trucks within the terminal from over 16 minutes to under 9 minutes, a decrease of 46.5%. However, a further increase in the number of straddles results in no further increase in daily throughput. It was observed that the throughput of the terminal is very sensitive to the speeds at which straddles travel. The management of the terminal has proposed a new heuristic job assignment rule for straddles, because the present rule does not assign the jobs to straddles closest to the truck requesting to load or unload a container. As a result a new heuristic job assignment rule was tested. The simulation results revealed that both the old and new rules performed equally well using performance indicators such as average container flow time, daily throughput, average waiting time of jobs, number of jobs in the queue, and straddle utilisation. Therefore, the new rule will not improve these performance measures if implemented     

In-car power line communications: Advanced transmission techniques

The increasing number of electronic control units (ECUs) inside a vehicle implies the need to develop and deploy on board robust, low latency and low complex telecommunication systems. In this respect, power line communications (PLC) is an attractive solution. The benefits provided by the introduction of power line communications in the in-car environment are multiple and they are related to the possibility of exploiting the existing and capillary wiring infrastructure to simplify the design of the in-vehicle data network (IVN) and, more importantly, to save weight and cost of the wiring harness. In this paper, we deal with the analysis of the performance achievable by applying innovative advanced modulation techniques to in-car measured power line channels, i.e., multicarrier (MC) and impulsive ultra wideband (I-UWB) modulation. We show that for low speed command and control applications, I-UWB is suitable since it requires lower power and lower computational efforts w.r.t. MC systems. Furthermore, we study the design of the optimal transmitted pulse to further improve the performance of I-UWB.