6,541 research outputs found

    The long and winding path to private financing and regulation of toll roads

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    Road transport has long been the dominant form of transport for freight and passenger movement throughout the world. Because most road projects require investments with long amortization periods and because many projects do not generate enough demand to become self-financing through some type of user fee or toll, the road sector remains in the hands of the public sector to a much greater extent than other transport activities. But governments throughout the world, including those of many poor African and South Asian countries, are commercializing their operations to cut costs, improve user orientation, and increase sector-specific revenue. There seems to be demand for toll roads in specific settings, but the problems met by many of this"first generation"of road concessions-from Mexico to Thailand-have given toll projects a bad reputation. Many mistakes were made, and tolling is obviously not the best solution for every road. Most of the alternatives aim at improving efficiency (lowering costs). But there are many ways of getting the private sector involved in toll roads, thus reducing public sector financing requirements for the sector. Understanding the context in which toll roads are viable is essential both for their initial success and for effective long-run regulation. The authors provide a broad overview of issues at stake from the viewpoint of both privatization teams and regulators responsible for supervising contractual commitments of private operators and the government, to each other and to users.Urban Services to the Poor,Roads&Highways,Public Sector Economics&Finance,Decentralization,Banks&Banking Reform,Roads&Highways,Toll Roads,Urban Transport,Public Sector Economics&Finance,Airports and Air Services

    Cooperative look-ahead control for fuel-efficient and safe heavy-duty vehicle platooning

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    The operation of groups of heavy-duty vehicles (HDVs) at a small inter-vehicular distance (known as platoon) allows to lower the overall aerodynamic drag and, therefore, to reduce fuel consumption and greenhouse gas emissions. However, due to the large mass and limited engine power of HDVs, slopes have a significant impact on the feasible and optimal speed profiles that each vehicle can and should follow. Therefore maintaining a short inter-vehicular distance as required by platooning without coordination between vehicles can often result in inefficient or even unfeasible trajectories. In this paper we propose a two-layer control architecture for HDV platooning aimed to safely and fuel-efficiently coordinate the vehicles in the platoon. Here, the layers are responsible for the inclusion of preview information on road topography and the real-time control of the vehicles, respectively. Within this architecture, dynamic programming is used to compute the fuel-optimal speed profile for the entire platoon and a distributed model predictive control framework is developed for the real-time control of the vehicles. The effectiveness of the proposed controller is analyzed by means of simulations of several realistic scenarios that suggest a possible fuel saving of up to 12% for the follower vehicles compared to the use of standard platoon controllers.Comment: 16 pages, 16 figures, submitted to journa
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