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Mohapatra S.S.,Indian School of Mines | Chandra S.,Central Road Research Institute
Proceedings of the Institution of Civil Engineers: Transport | Year: 2016

This paper proposes a practical approach to estimate the conflicting traffic volume caused by U-turns at uncontrolled median openings under mixed traffic conditions. Data were collected at 21 median openings on multi-lane divided roads in India (i.e. 13 on six-lane and eight on four-lane). The road width at the median opening is divided into three parts: zone of severe conflict, zone of safety and unaffected zone based on the placement of the left wheel of U-turning vehicles (left-hand drive rule followed in India). The first two zones together are considered as the conflicting zone for calculating the conflicting traffic. The proportion of opposing through traffic within the conflicting zone is considered as the conflicting traffic volume for U-turns. The conflicting volume at all the sections is estimated based on placement of through traffic across the width of the road and it is found to be dependent on the size of the U-turning vehicle. An equation is suggested to calculate the conflicting traffic based on the composition of U-turning traffic. The conflicting traffic on six-lane roads is found to be relatively, low but on four-lane roads, almost all of the opposing traffic becomes conflicting traffic for U-turns. © 2016, Thomas Telford Services Ltd. All rights reserved. Source

Nanda R.L.,Central Road Research Institute
Indian Concrete Journal | Year: 2011

A study was conducted to investigate filtration properties of cement-based grouts for rock foundation of a dam. One of the theories used in grouting was the Presso-filtration theory according to which the excess water from the grout pressed out into fine cracks in the rock and the cement grains jam in the rock fissures resulting in an improved grout when a thin mix was pumped in. The required properties of the fresh grout mix to allowed an easy penetration to be obtained using proper additives without adversely affecting the quality of the grouting works. A specially designed filter press was used to assess the stability of grout mixes, while the water expelled from the standard grout cup having 420 ml capacity under a pressure of 100 psi (0.7 MPa) applied for a total duration of 30 minutes and the thickness of the cake formed were measured. The filter press was also used to measure the filtrate volume and the thickness of the cake formed for testing various grout mixes of PPC and superfine cement with different ratios. Source

Pant P.,University of Birmingham | Shukla A.,Central Road Research Institute | Kohl S.D.,Desert Research Institute | Chow J.C.,Desert Research Institute | And 3 more authors.
Atmospheric Environment | Year: 2015

Ambient PM2.5 samples were collected at a high-traffic location (summer and winter 2013) and characterized for a large suite of elemental and organic markers. Concentrations were found to exceed the Indian PM2.5 air quality standard on several occasions, especially in the winter. Winter concentrations of several individual tracer species were several fold higher compared to summer, particularly for some PAHs and trace metals. Enrichment factors relative to crustal material showed significant enrichment for elements such as Ti, Sb, Pb and As, although Ba, often used as a marker for non-exhaust emissions from traffic was not found to be enriched appreciably. Crustal material was found to be an important contributor in the summer (14.3%), while wood burning (23.3%), nitrates (12.4%) and chlorides (12.3%) were found to be major contributors in winter. The contribution of road traffic exhaust emissions was estimated to be 18.7% in summer and 16.2% in winter. Other combustion sources (wood and other biomass/waste/coal) were found to be a significant source in winter, and contribute to the higher concentrations. Secondary sulphates, nitrates and chloride (the latter two in winter) and organic matter also contribute substantially to PM2.5 mass. © 2015 Elsevier Ltd. Source

Haskett M.,University of Adelaide | Oehlers D.J.,University of Adelaide | Mohamed Ali M.S.,University of Adelaide | Sharma S.K.,Central Road Research Institute
Engineering Structures | Year: 2011

Shear friction or aggregate interlock behaviour across sliding planes in concrete is now a well-established area of research. Two separate shear-friction approaches have been developed previously where these separate approaches either quantify the shear transfer capacity for a given crack displacement, normal stress and crack separation (Walraven Approach) or quantify the maximum shear transfer for a given crack confinement (Mattock Approach). In this paper, these two seemingly disparate approaches are combined to provide sufficient information to simulate all aspects of shear friction in initially cracked planes including a quantifiable failure limit for various crack separations and displacements. The shear friction components of initially uncracked sliding planes are also derived from the analysis of actively confined concrete cylinders and a failure envelope for initially uncracked sliding planes is developed. Hence, this paper provides the technique for determining the shear friction properties not only for initially cracked sliding planes, which have previously been available, but also for initially uncracked sliding planes which were not previously available so that shear-friction theory can now be used for all aspects of concrete. © 2011 Elsevier Ltd. Source

Haskett M.,University of Adelaide | Oehlers D.J.,University of Adelaide | Mohamed Ali M.S.,University of Adelaide | Sharmaj S.K.,Central Road Research Institute
Magazine of Concrete Research | Year: 2010

Shear friction or aggregate interlock behaviour across sliding planes in concrete is a well-established area of research used in numerical modelling and in the understanding of shear failure. Much of the research has been done on initially cracked planes. In this paper, both the shear stress (τN) and the crack separation (hcr) of the shear friction parameters for both initially cracked and uncracked concrete sliding planes are quantified mathematically in terms of the displacement (Δ) of the sliding plane, the compressive strength of the concrete (fco) and the normal stress (σN) across the sliding plane. A bound to these generic shear friction parameters (τN, hcr, Δ and σN) for both initially uncracked and cracked concrete is also developed. © 2010 Thomas Telford Ltd. Source

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