Roadway Infrastructure Research Articles

Comparison of Two Approaches for Modeling Freight Movement at Seaports

Seaports host international cargo operations and are primary generators of freight traffic in the United States. Truck/rail trip generation and modal split models provide public agencies with valuable information necessary to prioritize funds for roadway upgrade projects and port infrastructure modifications. This paper presents two approaches for developing freight trip generation models: regression analysis and backpropagation neural networks (BPN). These models are used for predicting the levels of cargo truck traffic moving inbound and outbound at seaports. Based on the Port of Miami case, it was found that the BPN model is more accurate than the regression model. However, the BPN model requires a sizable database. Using the BPN approach, the paper presents a new combined truck trip generation and truck-rail modal split model for the Port of Jacksonville. It was found that the primary factors affecting truck-rail volume are the amount and direction of cargo vessel freight, commodity type, and the particular weekday of operation. In summary, the neural network model results were found significantly accurate for both Florida ports.

Modeling subsoil drainage systems for urban roadways

Water infiltration and seepage in a roadway infrastructure is modeled from a cross section design of a residential street used by the City of Moncton (Department of Engineering). Field hydraulic conductivity measurements necessary for the modeling are also presented. Benefits of having a subsoil drainage systems (perforated drainage pipe and drainage mat) are well demonstrated. Some drainage problems caused by insufficient hydraulic conductivity, segregation, and limits on gradation curves for the gravel base foundation, as specified by the City of Moncton, are also discussed.Key words: roadway design, subsoil drainage, seepage modeling, field permeability measurements.

Coding of Road Information for Automated Highways

Communication of information from the roadway infrastructure to vehicles is expected to enhance Automated Highway Systems (AHS) by supporting subsystem functions like vehicle motion control, multiple vehicle coordination, and vehicle navigation. A suitable communication channel is information coding in the lateral reference used for automatic steering and lane keeping control, e.g. in the magnet reference system used by California PATH (Partners for Advanced Transit and Highways). The presented coding strategy was designed for and tested at the 1–15 test track near San Diego, CA, being prepared for the AHS demonstration of the National AHS Consortium (NAHSC) held in Aug. 1997. A number of aspects are discussed, concerning types and structure of coded information, encoding and decoding schemes, and possible future extensions.

La reducción del tráfico de automóviles: una política urgente de promoción de la salud

During the last few decades, traffic injuries have become one of the leading causes of death and disability in the world. In urban areas, traffic congestion, noise, and emissions from motor vehicles produce subjective disturbances and detectable pathological effects. More than one billion people are exposed to harmful levels of environmental pollution. Because its combustion engine generates carbon dioxide (CO2), the automobile is one of the chief sources of the gases that are causing the greenhouse effect. The latter has already caused a rise in the average ambient temperature, and over the next decades it will predictable cause significant climatic changes whose consequences, though uncertain, are likely to be harmful and possibly catastrophic. Aside from the greenhouse effect, the relentless growth of parking zones, traffic, and the roadway infrastructure in urban and rural areas is currently one of the leading causes of environmental degradation. Urban development, which is nearly always "planned" around traffic instead of people, leads to a significant deterioration in the quality of life, while it also destroys the social fabric. Unlike the private automobile, public transportation, bicycles, and walking help reduce pollution, congestion, and traffic volume, as well as the morbidity and mortality resulting from injuries and ailments related to pollution. Non-automobile transportation also encourages physical activity--with its positive effect on general health--and helps reduce the greenhouse effect. The drop in traffic volume and the increased use of alternate means of transportation are thus an integrated health promotion policy which should become an inherent part of the movement for the promotion of healthy cities and of transportation policies and economic policy in general.

Intermediate Automation Concepts for Incremental Deployment of Automated Highway Systems

Automated highway systems (AHS) are a promising concept whose implementation needs to take place in a modular and incremental manner. Immediate implementation of a fully automated highway system may not be feasible or desirable. It does not allow for the necessary testing and evolution of technology, markets, and social change. Recognizing the importance and challenge of progressive, evolutionary AHS deployment, six deployment assumptions are presented, three deployment issues are discussed, and several intermediate automation concepts for evolution toward AHS are proposed. Concepts are presented in the form of “market packages.” Some of these concepts are simple driver aiding systems; others are capable of supporting hands-off and feet-off driving. In the evolutionary path to AHS, a number of comfort and safety enhancements could be realized initially without large infrastructure modifications and without dedicated lanes. Intermediate deployment steps are necessary to help early deployment of partial automation, to allow AHS technology to mature, to establish user confidence, and to create market demand and public acceptance. The packages presented are designed so that they attract the driving public with comfort and safety benefits while requiring no significant roadway infrastructure modification and they encourage motorists to purchase (or retrofit) vehicles with equipment that enables hands-off and feet-off driving, thus building confidence in and creating demand for AHS.

Modal shift in Eastern Germany

The economic and political reunification of Germany in 1990 unleashed a transportation revolution in Eastern Germany. After forty years of public transport dominance under socialism, auto ownership and use skyrocketed with the transition to capitalism. In only three years, ridership on public transport fell by almost 50%, and auto registrations per 1,000 population rose by almost 60%. The main reason for the sudden shift in modal split is the large increase in real per-capita incomes of Eastern Germans. Their purchasing power rose dramatically thanks to massive financial aid from Western Germany and access to hard currency for the first time. In addition, the relative cost of auto use has fallen sharply since reunification because public transport fares rose ten-fold, while gasoline prices and auto prices fell. The massive shift from public transport to the auto has caused severe problems of pollution, safety, equity, and congestion in Eastern German cities, partly because of the suddenness of the modal shift. Urban transport policy in Eastern Germany should adopt some of the strategies used for years in Western Germany to tame the automobile, while at the same time allowing high levels of auto ownership. Such strategies include auto-free zones, traffic calming, extensive bicycle pathways, vehicle emission standards, and parking restrictions. Finally, large investments will have to be made in Eastern Germany's dilapidated roadway and public transport infrastructure.

Development of a novel two-stage fluidized bed incineration technology for the control of heavy metal emissions

Construction and Demolition Wastes (C&DW) are increasingly being reused in civil engineering applications, mainly in concrete production and base layers of roadway infrastructures. However, frequently the fine grain portion of these recycled aggregates is not considered suitable for those applications being landfilled instead of recycled. Moreover, the value-added utilisation of recycled C&DW in the construction of geosynthetic reinforced structures (steep slopes and retaining walls) is almost an unexplored field. This research assesses the feasibility of using fine-grain recycled C&DW as filling material of geosynthetic reinforced structures (GRS), appraising the physical, mechanical and environmental characterization of the construction and demolition material (C&DM), as well as, the direct shear and pullout behaviour of the interfaces between this material and three distinct geosynthetics (two geogrids and one geocomposite reinforcement or high strength geotextile). Direct shear tests results have shown that fine-grain recycled C&DW, properly compacted, exhibit similar shear strength to natural soils used commonly in the construction of GRS. The potential contamination of groundwater by these recycled C&DW was evaluated through laboratory leaching tests and, excepting the values of sulphate and total dissolved solids (TDS), this recycled C&DW complies with the provisions of European Council Decision 2003/33/EC for inert materials. High values of coefficients of interaction for C&DW/geosynthetic interfaces, a parameter of utmost importance in the design and performance of GRS, were achieved. The results herein presented support the viability of using these recycled C&DW as filling material for GRS construction.

Potential contributions of intelligent vehicle/ highway systems (IVHS) to reducing transportation's greenhouse gas production

The road transportation system (including automobiles, buses and trucks) has not yet made significant use of modern electronics technologies to enhance system operations. Intelligent vehicle/ highway systems (IVHS) is the label currently applied to the nascent attempts to use advanced technologies to enable travelers, vehicles and the roadway infrastructure to function as an integrated system IVHS technologies influence both the supply and demand sides of transportation, to promote enhanced operational efficiency and reductions in vehicle miles traveled. These changes can reduce the contribution of the transportation sector to global warming in ways that are explained qualitatively in the paper. Quantitative evaluation of the global-warming implications of IVHS must follow from further research on the technology and travelers' responses to it, and from development of the policy framework for IVHS implementation.

Knowledge-based advisory system for flexible pavement routine maintenance

One of the most pressing problems facing Canada is the condition of roadway infrastructure. Making good maintenance decisions requires years of practical experience and judgement. Expert systems have great potential for solving pavement maintenance problems that usually require significant human expertise for solution. Expert systems, also known as knowledge-based systems, have been used as a means for conveying pavement maintenance knowledge gained through research and field experience to individuals responsible for maintaining asphalt pavements. An expert system is defined as an interactive computer program which documents judgement, experience, intuition, and other information in order to provide knowledgeable advice.This paper describes the development of PMAS, a pavement maintenance advisory system, which can assist highway engineers in planning effective flexible or asphalt concrete pavement maintenance strategies. The system uses two alternative commercial expert system shells. The system questions the user in a multiple-choice format in everyday English and (or) by using pictures. The user responds by selecting one or more of the choices provided by the system. At the end of the consultation session, the system displays the most appropriate maintenance strategy along with its life expectancy. PMAS facilitates the decision-making process and could serve as a consultant for field engineers. Key words: expert system, knowledge-based system, pavement maintenance.