Nordiana Mashros

Extent of Highway Capacity Loss Resulting from Road Humps

Road humps are traffic calming devices placed across road widths solely as speed reduction mechanism. They include, speed cushions, junction tables, road humps. Whilst it is clear that 75mm deflection like road humps would reduce speed to 20km/h on average, determining their impact on traffic flow rate has often been poorly reported. Based on the hypothesis that on any route with humps mean stream flow will lie within highway capacity loss envelope; moving car observer survey method was used to determine mean stream flows as well as a volumes and speeds of ‘with and without’ road humps sections. The studies were carried out under day light and dry weather conditions so as to eliminate their effects. An important part of the study is employment of dynamic passenger car equivalent values for the road sections. Results show significant highway capacity loss and the mean traffic flows lying within capacity loss envelope. The study concluded that although road humps are effective mechanism for vehicle speed reduction, their resultant highway capacity loss is significant.

Use of Imaging Techniques for Viewing the Internal Structure of Rubberised Asphalt Mixtures

This paper presents the application of different imaging techniques for viewing the internal structure of rubberized asphalt mixture as road materials. Two imaging techniques were used to capture the internal structure images of its compacted samples i.e. X-ray Computed Tomography (non-destructive method) and Scanning Electron Microscope, SEM (destructive method). Since a lot of previous researchers have produced extensive works on the mechanical properties, therefore, this study is an attempt to introduce the microstructure of rubberized asphalt mixtures produced using dry process method. Two types of dry mixed rubberized asphalt mixture were prepared by modifying a Hot Rolled Asphalt Mixture (HRA 60/20) with different crumb rubber sizes. A mixture of conventional HRA 60/20 was also scanned for comparison. The illustrations are aimed to provide the researchers more information regarding their internal structure distribution.Keywords: Imaging techniques, X-ray Computed Tomography, Scanning Electron Microscope, Rubberised Asphalt Mixture

Exploration of sample quantiles and mean speed distributions

In highway traffic analysis, speed and traffic flow are essential parameters. The 85th and 15th percentiles are commonly used. Comparative assessments of qualitative service often rely on descriptive statistics of speeds. In some studies, the focus has been on sampling distribution of the mean instead of the sampling distribution of the percentile while some have applied the binomial test for percentiles. This paper aims to explore two statistical tests on 85th percentile speed using an impact study of rainfall carried out in Terengganu. Hypothesis was set up for performing simple percentile or quantile test and sample mean test. The normality of the data was evaluated and results show that speed reduction was statistically significant in all cases. The paper concluded statistical test for percentiles based on Crammer theory of asymptotic distribution of sample quantiles is a better fit when testing for statistical significance of speed changes occasioned by rainfall.

Extent of highway travel time differentials resulting from rainfall intensities

Travel time on a roadway segment is what most road users are concerned about. It is a useful guide for measuring road users’ perception of the quality of roadway service. Rainfall affects traffic flows by reducing drivers’ visibility and road surface friction among others. These reductions have profound impacts on travel time. The aim of the paper is to determine the impact of rainfall intensities (slight, moderate and heavy) on travel time. The impact study was carried out at locations along Terengganu East Coast Highway 5, between November 2010 and February 2011. Based on the hypothesis that rainfall intensity has effect on travel time, a ‘with-and-without rainfall impact study for both directions of a single carriageway was conducted. Volume, speed, headway, gaps and types of vehicles collected by way of automatic traffic counter continuously for three months estimated and compared. Rainfall data were collected and supplemented with data supplied by the Malaysian Hydrology Department. Results show that light and moderate rainfall will cause a travel time increase of about 0.43 and 0.54 minutes per kilometer by respectively; whereas heavy rainfall will account for travel time increase of 0.74 minutes per kilometer. It also shows that traffic kinematics and shockwave propagations at the onset of rainfall can also be called to account for travel time differentials. The paper concluded that rainfalls irrespective of their intensities have significant impact on roadway travel time.

Effects of Kaolin Clay on the Mechanical Properties of Asphaltic Concrete AC14

This study investigated the effect of kaolin clay on the mechanical properties of asphaltic concrete AC14 through Marshall Stability, resilient modulus, and dynamic creep tests. Four replacement levels of kaolin clay (2%, 4%, 6%, and 8% by weight of the binder) were considered. Kaolin clay functioned as an effective filler replacement material to increase the mechanical properties of asphalt mixtures. Asphaltic concrete with 2% to 4% kaolin clay replacement level exhibited excellent performance with good stability, resilient modulus, and creep stiffness.

Experimental and numerical study on softening and pinching effects of reinforced concrete frame

The response analysis of reinforced concrete (RC) structures subjected to strong earthquake motions requires material models that are able to simulate cyclic deformation and damage realistically. This paper presents the results of a study of pinching and softening behaviour in an RC frame subjected to cyclic loading. The experiment was conducted on a full-scale RC frame at Indian Institute of Technology Roorkee in India. The hysteretic curve representing the response of the frame was generated. Finite element analyses were performed to predict the response of the frame under cyclic loading both before and after the test using different computer codes, ABAQUS and OpenSees. Although the experiment was conducted using load control, the finite element simulations were performed using displacement control. The result from both models are compared to the experiment and to each other and a detailed discussion is provided on the modelling capabilities of the two software in capturing the pinching and softening behaviour observed in the test.