Search

To address the transportation sector's contribution to climate change problems across North America (NA), passenger rail is an attractive solution. However, NA passenger rail traditionally relies on diesel motive power, which has been associated with causing health problems of noise, vibrations, and emissions. High costs of overhead and (or) third rail infrastructure have mostly precluded electrification. This paper examines the impact of battery size on fuel cell stack efficiency for hydrogen fuel cell – battery hybrid (hydrail) railway propulsion systems using dynamic simulations as opposed to existing simulations in the literature that rely on static efficiency values. The journey of the British Rail Class 156 diesel multiple unit is simulated over the round trip from Trehafod to Treherbert (UK) using a series hybrid architecture powertrain. Dynamic simulations at incremental battery masses were used to assess fuel cell efficiency, maximum power, and overall hydrogen consumption. Battery mass is employed as a proxy for power and energy capability of the battery. Results suggest that hydrail passenger railway systems work well, with hydrogen fuel cells handling most load dynamics. Hybridization with batteries works best and reduces fuel cell stack size and hydrogen consumption, with overall 64% stack efficiency. [ABSTRACT FROM AUTHOR]

Culverts are important components of highway infrastructure. They are structurally designed to support earth and live traffic loads. Corrugated steel pipes (CSPs) are widely used as culverts in North America in different geometries. However, due to the corrosive nature of the stormwater passing through the culverts, it is common to find CSPs with partially or entirely lost inverts. Dependent on site, depth of cover and embedment conditions, invert deterioration would not necessarily result in culvert failure. This paper presents the results of a laboratory testing campaign that evaluates the structural capacity of two circular CSPs and their equivalent arch CSP through the application of a vertical static loading. The circular pipe samples had a length of 6 ft (1.82 m) and a diameter of 60 in. (1.52 m). The same length arch pipe sample had a span of 71 in. (1.8 m) and a rise of 47 in. (1.19 m). The invert of the arch and one of the circular CSPs were cut to simulate heavily corroded culverts in service. The pipe samples were embedded under two feet (0.6 m) of cover using one foot (0.3 m) of sand and one foot (0.3 m) of coarse aggregates on top, simulating a base course layer of pavement. The results of testing showed that the invert-cut circular CSP was highly dependent on its ring stiffness. While, the invert-cut arch CSP took advantage of its arch geometry and was able to resist the applied load without significant loss in the sample pipe's horizontal dimension. [ABSTRACT FROM AUTHOR]

Resilient design requires information about a structure's response to a variety of exposures such that systems can be implemented to prevent unacceptable losses. For the case of critical infrastructure like bridges, losses associated with structural damage and traffic closures from fire events can be substantial. Despite this, there are no specific code requirements for bridge fire safety in different national jurisdictions, particularly in North America and Europe, and only minimal guidance available for establishing the fire resistance requirements of bridges. Research into the fire safety of bridges is ongoing but knowledge gaps persist that limit practitioners' ability to conduct performance-based fire designs using the latest state of existing research. This paper provides a first-stage state of the art review of bridge fire research conducted to date in effort to summarize key findings and make available the most relevant information for researcher and practitioner use. The key research themes considered as subdivisions are fire hazard and risk assessment, bridge fire scenario modelling, and the structural response of steel and composite steel-concrete, cable-supported, concrete, and fiber reinforced polymer bridges to fire. The authors conclude the study with identified knowledge gaps and priority research areas. [ABSTRACT FROM AUTHOR]

Recent surveys have indicated that between 30% and 40% of all bridges in North America are in various states of deterioration. Funding is limited owing to the existence of other deficient components of the transportation infrastructure. It is clear, therefore, that the return on the available funding needs to be maximized. This paper presents a review of publications on cost optimization of concrete bridge components and systems and then continues with a review of the state-of-the-art in life-cycle cost (LCC) analysis and design of concrete bridges. The main objective of the paper is to encourage bridge engineers to move towards the increased use of advanced analysis and design optimization methods. [ABSTRACT FROM AUTHOR]

This paper synthesizes information obtained from a comprehensive literature review and agency surveys on the state of the practice of fixed automated spray technology (FAST) systems. Experience with FAST systems in North America and Europe has revealed a mixed picture. On the one hand, several studies have indicated reductions in mobile operation costs and significant reductions in crash frequency, resulting in favorable benefit-cost ratios. On the other hand, there have been a variety of problems related to activation frequency, system maintenance and training. Installing a FAST system is complex and the challenges are often site specific. However, the evaluations cited show that FAST systems can be cost-beneficial if their locations are carefully chosen and if the system is supported with reliable environmental sensors. Finally, it was found that application of FAST systems in North America have recently increased. [ABSTRACT FROM AUTHOR]

Concrete pavements are well known for long structural life. The major challenge, however, is to provide a durable surface with adequate skid resistance for economy and safety. This paper examines the long-term frictional performance of eight different surface textures on 197 sections of concrete pavements within the long-term pavement performance (LTPP) program database. Analysis shows that tined and (or) grooved textures maintain consistently higher skid resistance over time and the surface friction of concrete pavements is less sensitive to ambient temperature. Cumulative traffic passes are more sensitive to longevity of friction than the cumulative axle loads. Five alternative models have also been successfully developed for prediction of the long-term skid resistance of concrete pavements as a function of texture type, cumulative traffic passes, speed, and concrete compressive strength. These models were shown to be statistically significant at 95% confidence levels with reasonable prediction accuracy. Les chaussées en béton sont reconnues pour leur longue durée de vie structurale. Le principal défi est toutefois de fournir une surface durable présentant une antidérapance adéquate pour la sécurité et l’économie. Le présent article examine le comportement au frottement de huit différentes textures de surface sur 197 sections de chaussées en béton dans la base de données du programme « long-term pavement performance (LTPP) ». L’analyse montre que des textures crantées et (ou) rainurées conservent de façon constante une meilleure antidérapance dans le temps et le frottement à la surface des chaussées en béton est moins sensible à la température ambiante. Le cumulatif des passages de la circulation est plus sensible à la longévité du frottement que le cumulatif des charges par essieu. Cinq autres modèles ont été développés avec succès pour prédire l’antidérapance à long terme des chaussées en béton en fonction du type de texture, du cumulatif des passages de la circulation, de la vitesse et de la résistance en compression du béton. Ces modèles se sont avérés statistiquement significatifs avec des coefficients de confiance de 95 % et une précision raisonnable de prévision. [ABSTRACT FROM AUTHOR]

Residential construction has changed little in decades. In North America, houses are constructed predominantly with cast-in-place (CIP) concrete basement foundations and “custom-built” wood platform - framing structures. To improve the productivity of residential construction, a precast concrete foundation (PCF) system was developed by the University of Alberta and its industrial partners. Although the PCF system can be built much faster and better than conventional CIP foundations, it has not been considered a viable alternative in residential construction due to the belief that it is costly and less flexible. To overcome this perception, special research efforts were made to address issues of manufacturability, constructability, and standardization. This paper proposes an innovative design of the PCF system that satisfies functional requirements, while obtaining a minimum total cost and achieving flexibility. The unique features include a modularized rib structure, external insulation, and simplified bolted connections. A comparative analysis between PCF and traditional CIP concrete foundation systems is also presented. [ABSTRACT FROM AUTHOR]

Road and highway maintenance is vital for the safety of citizens and for enabling emergency and security services to perform their essential functions. Accumulation of snow and (or) ice on the pavement surface during the wintertime substantially increases the risk of road crashes and can have negative impact on the economy of the region. Recently, road maintenance engineers have used pavement surface temperature as a guide to the application of deicers. Stations for road weather information systems (RWIS) have been installed across Europe and North America to collect data that can be used to predict weather conditions such as air temperature. Modelling pavement surface temperature as a function of such weather conditions (air temperature, dew point, relative humidity, and wind speed) can provide an additional component that is essential for winter maintenance operations. This paper uses data collected by RWIS stations at the City of Ottawa to device a procedure that maximizes the use of a data batch containing complete, partially complete, and unusable data and to study the relationship between the pavement surface temperature and weather variables. Statistical models were developed, where stepwise regression was first applied to eliminate those variables whose estimated coefficients are not statistically significant. The remaining variables were further examined according to their contribution to the criterion of best fit and their physical relationships to each other to eliminate multicollinearities. The models were further corrected for the autocorrelation in their error structures. The final version of the developed models may then be used as a part of the decision-making process for winter maintenance operations. [ABSTRACT FROM AUTHOR]

The condition of sewer pipes in North America has severely deteriorated, over the last few decades, creating a need for rehabilitation. Sewer rehabilitation methods are numerous and are constantly being developed, benefiting from emerging technologies. The implementation of these methods is driven by the need to improve quality and to reduce cost and project duration. One of the rapidly expanding fields in the sewer rehabilitation industry is trenchless technology. Due to the large number of methods associated with emerging new technologies in this field, selecting the most suitable method can be a challenging task. Selection in this environment, without a computerized tool, may also suffer from the limited knowledge and (or) experience of the decision-maker and could result in overlooking some of the suitable methods that could do the job at less cost. This paper describes a recently developed system for rehabilitation of concrete and clay sewer pipes and focuses primarily on two of its components: (i) the database management system (DBMS) and (ii) the decision support system (DSS). The system can assist municipal engineers and contractors in selecting the most suitable trenchless rehabilitation technique that specifies job conditions and user requirements. An example application is presented to demonstrate the use and capabilities of the developed system.Key words: pipe defects, rehabilitation, sewer pipes, database management systems, decision support systems, multi-attribute utility theory.Les conditions des conduites d'égout en Amérique du Nord se sont déteriorées sévèrement durant les dernières décennies, créant un besoin pour une remise en état. Les méthodes de remise en état de systèmes d'égout sont nombreuses et en développement constant, bénéficiant de technologies émergentes. L'utilisation de ces méthodes est motivée par le besoin d'améliorer la qualité, la réduction des coûts et la durée du projet. Un des domaines en expansion rapide dans l'industrie de la remise en état de systèmes d'égout est la technologie sans tranchée. À cause du large nombre de méthodes associées aux nouvelles technologies émergentes dans ce domaine, la sélection de la méthode la plus appropriée peut être une tâche difficile. La sélection dans cet environnement, sans outil informatique, peut aussi souffrir des connaissances et/ou expériences limitées du preneur de décisions, et peut conduire à l'omission de méthodes appropriées qui pourraient accomplir le travail à moindre coût. Cet article décrit un système récemment développé pour la remise en état de conduites d'égout en béton et en argile, et se concentre principalement sur deux de ses composantes: (i) le système de gestion de bases de données « database management system (DBMS) » et (ii) le système d'aide à la décision « decision support system (DSS) ». Le système peut assister les ingénieurs municipaux et les contracteurs dans la sélection de la technique de remise en état sans tranchée la plus appropriée selon les conditions de travail et les exigences de l'usager. Un example d'application est présenté afin de démontrer l'usage et les capacités du système développé.Mots clés : défauts de conduites, remise en état, conduites d'égout, système de gestion de bases de données, système d'aide à la décision, theorie de services à attributs multiples.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]