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  • 1
    Online Resource
    Online Resource
    Truck Weights on Municipal and National Roads without Weight Enforcement
    SAGE Publications ; 2019
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2673, No. 2 ( 2019-02), p. 275-284
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2673, No. 2 ( 2019-02), p. 275-284
    Abstract: One of the main causes of premature deterioration in pavement structures is overweight heavy vehicles. To characterize these vehicles, real loads of motor vehicles of more than four tons should be monitored, especially vehicles classified as C2 (2-axles, single units), C3 (3-axles, single units), T3-S2 (5-axles, single trailer) and T3-S3 (6-axles, single trailer) type, as they represent 99.5% of the Costa Rican truck fleet. This study includes six temporal weighing surveys on municipal roads and seven weighing surveys on national roads, comprising the weight of 525 and 554 trucks, respectively. On municipal roads, C2 vehicles with bulk and wagon body types are predominant (67% of surveyed vehicles), whereas on national routes T3-S2 vehicles predominate (42%). Likewise, it was determined that most of exceeding data correspond to vehicles transporting pit material, construction materials, and merchandise on both types of roads. Compared with municipal roads (8%), the percentage of overweight vehicles is more than twice that on national roads (18%) where weight regulations are not enforced. To estimate updated and realistic load data that can be included in pavement design manuals and guides, the same results are provided in parameters such as truck factors and load spectra.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198119828283
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2019
    detail.hit.zdb_id: 2403378-9
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  • 2
    Online Resource
    Online Resource
    Updated Zone of Intrusion Envelopes in the Manual for Assessing Safety Hardware Impact Conditions
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications
    Abstract: Roadside barriers are used to shield fixed objects near the roadway and are designed to mitigate the severity of run-off-road crashes near those fixed objects. The zone of intrusion (ZOI) defines the potential location of a vehicle component above and beyond the top face of the barrier during an impact, and therefore indicates if there is a potential that a fixed object located behind a barrier could interact with the vehicle during redirection. Previous ZOI envelope guidelines were based on older vehicle models and test results. Further review was required to update the guidelines for contemporary vehicles and impact conditions in accordance with the American Association of State Highway and Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH). A literature review of full-scale crash tests and computer simulations were used to identify the ZOI envelope shapes for MASH test levels 2–5. Simulations were calibrated using test data and were used to investigate gaps in the full-scale test data. Conservative guidelines were developed from the combined simulation and test data, and recommended ZOI envelope shapes were developed that conservatively bounded the ZOI results. Results were presented for potential revision of ZOI envelope guidelines in the AASHTO Roadside Design Guide. Future recommendations to improve ZOI measurements in test data and simulation modeling were also presented.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/03611981231166680
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
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  • 3
    Online Resource
    Online Resource
    Accessibility, Affordability, and Addressing Informal Services in Bus Reform: Lessons from Bogotá, Colombia
    SAGE Publications ; 2017
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2634, No. 1 ( 2017-01), p. 35-42
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2634, No. 1 ( 2017-01), p. 35-42
    Abstract: Many cities in the developing world are reforming transit by formalizing bus services to capture user and nonuser benefits. A forerunner in transit reform, the city of Bogotá, Colombia, first implemented the TransMilenio bus rapid transit (BRT) system and then more recently undertook a large-scale initiative to formalize and regulate traditional urban buses in the city. This integrated public transport system [Sistema Integrado de Transporte Público (SITP)] is transforming Bogotá’s traditional urban bus system into a regulated, concessionary system with restructured bus routes that integrates operations, fares, and infrastructure with the TransMilenio BRT. An investigation was conducted to determine whether the SITP has increased affordability and employment accessibility for public transit users in Bogotá. Results revealed that most accessibility improvements resulted from the recent expansion (and significantly higher speeds) of TransMilenio rather than the SITP. Results of an analysis conducted with budget constraints to determine affordable accessibility indicated that employment accessi bility was reduced overall; however, the new integrated fare increased accessibility over traditional buses, especially on the periphery and in southern areas of the city, as a result of reduced transfer costs. Overall, results partly explain the lack of enthusiasm for the bus reform process on the part of public transit users and the political discomfort that becomes apparent when embarking on this process in developing-world cities. Also, more incremental, flexible reform might be crafted for public transportation systems that are dominated by informal services.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2634-06
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2017
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  • 4
    Online Resource
    Online Resource
    As-Encountered Prediction of Tunnel Boring Machine Performance Parameters using Recurrent Neural Networks
    SAGE Publications ; 2020
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2674, No. 10 ( 2020-10), p. 241-249
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2674, No. 10 ( 2020-10), p. 241-249
    Abstract: The earth pressure balance tunnel boring machine (TBM) is advanced excavation machinery used to efficiently drill through subsurface ground layers while placing precast concrete tunnel segments. They have become prevalent in tunneling projects because of their adaptability, speed, and safety. Optimal usage of these machines requires information and data about the soil of the worksite that the TBM is drilling through. This paper proposes the utilization of artificial intelligence and machine learning, particularly recurrent neural networks, to predict the operational parameters of the TBM. The proposed model utilizes only performance data from excavation segments before the location of the machine as well as its current operating parameters to predict the as-encountered parameters. The proposed method is evaluated on a dataset collected during a tunneling project in North America. The results demonstrate that the model is effective in predicting operation parameters. To address the potential issue of gathering sufficient data to retrain the model, the possibility of transferring the trained model from one tunnel to another is tested. The results suggest that the model is capable of performing accurately with minimal or even no re-training.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.1177/0361198120934796
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2020
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  • 5
    Online Resource
    Online Resource
    Methodology for Determining Performance Life of Hot-Mix Asphalt Mixtures
    SAGE Publications ; 2016
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2589, No. 1 ( 2016-01), p. 110-118
    Details
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2589, No. 1 ( 2016-01), p. 110-118
    Abstract: A critical component of the life-cycle cost analysis for staged design and rehabilitation of flexible pavements is to estimate the service lives of various hot-mix asphalt (HMA) mixtures, which in some cases is carried out subjectively. This paper describes a process for using the existing data to develop an objective and data-driven process for estimating the service lives of common HMA mixtures. Spatial information along with construction records and distress and functional condition logs are merged to assess the “cradle-to-grave” service lives and deterioration patterns, statewide or regionally. One of the most challenging steps was linking separate databases to compile a comprehensive pavement performance database. The end result was an online tool that enabled the extraction of HMA service life data and descriptive statistics of several thousand road sections. The probabilistic performance life of each common mix was then estimated through an integrated approach of survivability analysis that considers the historical longevity of mix types, the age of the HMA surface course, distress history–based life predictions, field case study life predictions, and department of transportation personnel perceived service lives. The results as applied to Texas data showed bimodal longevity distributions of service life. In general, the mean service life of the analyzed dense-graded mix met or exceeded the mean perceived service life expressed by two dozen pavement engineers statewide. However, a fraction of the projects exhibited shorter lives because of a number of technical and institutional factors. Overall, the proposed methodology proved to be a consistent process when assessing HMA service life.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    URL: Article
    DOI: 10.3141/2589-12
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2016
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