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Study on Gradation Improvement of Gravel and Sand for Surface Layer of Railway Subgrade by Blending Method
Issue:
Volume 4, Issue 1, January 2019
Pages:
1-6
Received:
26 September 2018
Accepted:
22 December 2018
Published:
25 March 2019
Abstract: As the direct foundation of the track, the surface layer of high-speed railway subgrade bed is one of the important parts of the subgrade. Its main function is to transmit and spread the vertical load of the upper ballast bed and the vehicle dynamic load to maintain the long-term stability of the subgrade bed surface. So, the material for the surface layer of subgrade bed should have high strength, elastic modulus, wear resistance and invented filtration. The graded sand gravel, which is used as the filler for the surface layer of railway subgrade bed, has such features as high mechanical strength, high water stability, easy obtaining, convenient construction, low cost and so forth. The purpose of this study is to physically blend local sand gravel materials to solve the defect of excessive fine particle content, so that it can meet the grading requirements of the specification and design standards and also to provide a general calculation method and solution for the mix ratio design of natural sand gravel. In combination with a foreign project, the dissertation expatiated on the calculation method for improving the gradation defects of natural sand gravel by the blending method. Then, according to local conditions, the author successfully solved the gradation defects of natural sand gravel mixture with the said method and achieved good economic and social benefits.
Abstract: As the direct foundation of the track, the surface layer of high-speed railway subgrade bed is one of the important parts of the subgrade. Its main function is to transmit and spread the vertical load of the upper ballast bed and the vehicle dynamic load to maintain the long-term stability of the subgrade bed surface. So, the material for the surfa...
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Spatial and Temporal Analysis of Seasonal Traffic Accidents
Homayoun Harirforoush,
Lynda Bellalite,
Goze Bertin Bénié
Issue:
Volume 4, Issue 1, January 2019
Pages:
7-16
Received:
17 January 2019
Accepted:
21 February 2019
Published:
26 April 2019
Abstract: This paper presents an approach to analyze spatial and temporal (spatiotemporal) patterns of traffic accidents and to organize them according to their level of significance. This approach was tested using three years (2011-2013) of traffic accident data for Sherbrooke. The spatiotemporal patterns of traffic accidents were analyzed using kernel density estimation (KDE) for four different seasons. Two different crash measures were compared: simple crash counts and severity-weighted crash counts. The results show that severity-weighted crash counts reveal the effect of a single fatal/severe injury or light injury crash on the patterns. However, the lack of a significance test is the main drawback of the KDE. Therefore, this paper integrates the KDE with local Moran’s I to identify clusters of statistical significance for traffic accidents within each area. Thus, after the density is calculated by the KDE, it is then applied as the attribute (input value) for calculating local Moran’s I. Our findings show that the method was successful to detect traffic accident clusters and hazardous areas in Sherbrooke.
Abstract: This paper presents an approach to analyze spatial and temporal (spatiotemporal) patterns of traffic accidents and to organize them according to their level of significance. This approach was tested using three years (2011-2013) of traffic accident data for Sherbrooke. The spatiotemporal patterns of traffic accidents were analyzed using kernel dens...
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Influence of Recycling Agent on Surface Free Energy of Asphalt Cement
Saad Issa Sarsam,
Rana Khalid Hamdan
Issue:
Volume 4, Issue 1, January 2019
Pages:
17-23
Received:
24 March 2019
Accepted:
22 April 2019
Published:
9 May 2019
Abstract: Reliable surface free energy characterization is required in order to implement the suitable recycling agent into aged asphalt. One proven method to estimate asphalt surface free energy is to calculate it using contact angles measured with various liquids. The efficiency of recycling agent in terms of its impact on rheology and surface free energy of asphalt cement is vital in the decision of recycling aged asphalt concrete. In this investigation, asphalt cement of penetration grade 40-50 was subjected to aging using the thin film oven test. The aged and the control asphalt cement samples have been digested with various percentages of two type of polymer recycling agents (Polyethylene and crumb rubber). Recycled and control asphalt cement specimens were subjected to physical and rheological properties determination, while the surface free energy was determined using Wilhelmy plate and Sessile drop methods. It was observed that the surface free energy decreases after aging, while it increases after digestion with polymers. Digestion of aged asphalt cement with polyethylene was able to retain the original surface free energy of asphalt cement before aging, while a higher percentage of 1.5 polyethylene has improved the surface free energy beyond the requirements. Digestion of aged asphalt cement with crumb rubber was able to increase the surface free energy of asphalt cement by one-fold of that before aging when Wilhelmy plate method was implemented, while a higher percentage of 1.0 of crumb rubber has improved the surface free energy beyond the requirements.
Abstract: Reliable surface free energy characterization is required in order to implement the suitable recycling agent into aged asphalt. One proven method to estimate asphalt surface free energy is to calculate it using contact angles measured with various liquids. The efficiency of recycling agent in terms of its impact on rheology and surface free energy ...
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Assessing Pedestrian Environment: A Review on Pedestrian Facilities in Rajshahi City Corporation Area
Aftabun Nahar,
Abdul Mohaimenu Mim,
Md. Mostafizur Rahman
Issue:
Volume 4, Issue 1, January 2019
Pages:
24-30
Received:
3 March 2019
Accepted:
9 April 2019
Published:
15 May 2019
Abstract: Traffic congestion and lack of public pedestrian space are faced by most urban areas in Bangladesh. Provision of facilities for pedestrian is not increased as a rate of increase in population. Consequently pedestrians are at greater risk for their safety, especially in the commercial zones of large cities. In Rajshahi, walkways are constructed recently; but the facilities are not enough for providing friendly environment. The demand for the improvement of pedestrian facilities is raised due to the reasons such as difficulties in crossing busy intersections, conflicts among pedestrians and vehicles, physical barriers, low visibility, improper design of handicapped accessible ramps and so on. The purpose of the study is to assess pedestrian environment to show how extent the pedestrian facilities are friendly for walking. The pedestrian friendly environment is evaluated under five criteria i.e. Connection, Convenience, Convivial, Comfortable and Conspicuousness. Rajshahi City Corporation area is divided into four zones for comparative view of existing pedestrian planning condition such as Residential Zone, Commercial zone, Recreational zone and Industrial zone. For fulfilling the objectives, questionnaire survey has conducted for user perception on pedestrian environment. Sample size was 267 according to the population of RCC area in 2017 with 95% confidence level. The method of the sampling is random selection. This study reveals that pedestrian environment is not friendly everywhere and worse in commercial zone rather than other three zones. Main lacking of pedestrian friendly environment is Conviviality among five criteria. Pedestrian’s recommendation is also included. It is expected that the results will be highly useful for improvement of walkways for efficient, adequate and safer movement of the pedestrians.
Abstract: Traffic congestion and lack of public pedestrian space are faced by most urban areas in Bangladesh. Provision of facilities for pedestrian is not increased as a rate of increase in population. Consequently pedestrians are at greater risk for their safety, especially in the commercial zones of large cities. In Rajshahi, walkways are constructed rece...
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Predicting CBR Values of Black Cotton Soil Stabilized with Cement and Waste Glass Admixture Using Regression Model
Ibrahim Abdulkarim Ikara,
Ali Musa Kundiri,
Abbagana Mohammed
Issue:
Volume 4, Issue 1, January 2019
Pages:
31-36
Received:
7 March 2019
Accepted:
22 April 2019
Published:
15 May 2019
Abstract: In highway constructions, sub-grade and sub-base soil stabilization has been used as one of the prime and major process for many years in order to improve the engineering properties of soil. The strength of theses layers is indicated by their California bearing ratio (CBR) value which is quite expensive and time consuming. In order to overcome this situation, this study presents a methodology for predicting soaked California Bearing Ration (CBR) value of Black Cotton Soil Stabilized with Cement and Waste Glass Admixture using Multiple Regression Analysis (MRA). Experimental test results such Atterberg limit (Liquid limit (LL), Plastic limit (PL) and Plasticity index (PI)), Compaction characteristics of two compactive efforts namely standard proctor (SP) and modified proctor (MP) (maximum dry density (MDD) and optimum moisture content (OMC)), CBR, Waste glass (WG) content and Cement content (Cm), obtained from a laboratory at Abubakar Tafawa Balewa University Bauchi, Nigeria, have been employed in developing multiple regression models. California Bearing Ration was taken as the dependent variables while Liquid limit, Plastic limit, maximum dry density, optimum moisture content, waste glass content and Cement content were taken as independent variables. The regression analysis calculated the error mean square (MSE) for each possible model, and models with large MSE were not selected for the best regression equations. The best models have a minimum value of MSE occurring for the six-variable model (Cm, WG, LL, PL, OMCsp, MDDsp) and (Cm, WG, PL, LL, OMCmp, MDDmp) with a corresponding higher value of coefficient of multiple determination R2 = 0.98 and 0.94. The performance evaluation of the fitted regression models indicates a strong correlation (R2 = 0.89 - 0.98) between the mentioned variables, and the model equations developed from this work provided a very good prediction of the response, as the equations can be employed for making estimates of soaked CBR of other black cotton soils having similar geotechnical properties.
Abstract: In highway constructions, sub-grade and sub-base soil stabilization has been used as one of the prime and major process for many years in order to improve the engineering properties of soil. The strength of theses layers is indicated by their California bearing ratio (CBR) value which is quite expensive and time consuming. In order to overcome this...
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