No abstract

This study describes driver’s car following headway on multilane highways.  The aim of this study is to analyse the driver’s car following headway along multilane highway at four selected locations.  The objectives of this study were to determine car headway at Jalan Batu Pahat – Ayer Hitam multilane highway and to develop linear regression models to present the relationships between headway and speed.  Videotaping method was used in field data collection during peak hours.  Data were extracted from recorded video by using the image processing technique software.  The distance headways and associated vehicles speeds were classified into vehicle following category by vehicle type: car following car, car following heavy goods vehicle, heavy goods vehicle following heavy goods vehicle and heavy goods vehicle following car categories.  Linear regressions models were used to develop the relationships between headway and speed. Based on all headway distribution, it is found that patterns of the vehicle headways at four study locations were similar, which shown a significant number of the vehicles travel at headways less than 5 seconds.  Furthermore, it can be concluded that many drivers tend to follow the vehicles ahead closely on multilane highways.  The regression models were significantly reliable based on their R-square values which are ranging between 0.80 and 0.95.  From the analysis, cars were found to maintain larger headways when following heavy goods vehicles compare to when following other cars.

Grouted Macadam composite pavement (GMCP) is generally a composite pavement which is manufactured by preparing a highly workable fluid mortar which is specially designed with a very high early and 28 day strength (1 day -45 MPa, 28 day -105 MPa) by filling the flowing fluid mortar into a very open porous asphalt skeleton (25-32% Voids in Mix -VIM). The combination of both components will produce a semi-rigid pavement or GMCP which has the best features of both rigid concrete and flexible bituminous pavement where it will replace the conventional wearing course. This paper will investigate the significance difference of GMCP produced by the 3 different aggregate gradations by Road Engineering Association of Malaysia (REAM) in volumetric properties, durability and strength. The best quality fluid grout was chosen to fill the porous asphalt skeleton and GMCP was subjected for compression test, VIM and indirect tensile test (IDT) to check on its performance. The results show that the 3 different aggregate gradations significantly affect the volumetric properties, durability and strength. Furthermore it will also help in reducing pollution and helps with the current environmental problems.

Traffic accidents have become a major socio-economic problem in Malaysia as it is the primary cause of mortality. Over 60 percent of these fatal accidents occurred on rural roads. Nearly half of all fatalities took place on federal roads and over a quarter happened on state roads. It is also estimated that about 2 percent of the country’s Gross Domestic Product (GDP), or approximately RM 9 billion, is lost through road accidents. Previous studies managed to develop several models for modelling the occurrence of accidents, but most of these models have plenty of deficiencies. The following study focuses on stochastic regression models, such as Poisson, Negative Binomial, Zero-Inflated Poisson and Zero-Inflated Negative Binomial with excess zero outcomes on the response variables. Furthermore, in order to specify the regression relationship with a sophisticated result, R-statistical programming is used. The method used is also the updating approach in predicting potential road accidents, which can also produce an accuracy probability of hazardous locations. Based on road accident data collected over a five-year period from 2010 to 2014 at Federal Road F0050: Kluang-A/Hitam- B/Pahat in Johor, Malaysia, results of this study show that Zero Inflated model performed better, in terms of the comparative criteria based on the AIC value.

The assessment of magnesium sulphate attack on concretes containing rice husk ash (RHA, 20wt% of the cementitious materials) with various average particle sizes was investigated. The total cementitious materials were 390 kg and the water-to-binder ratio (W/B) was 0.53 for all mixtures. Specimens were initially cured in water for 7 d and then immersed in the 3wt% magnesium sulphate solution for up to 111 d of exposure. The specimens were subjected to drying-wetting cycles to accelerate sulphate attack. In addition to the visual monitoring of the specimens, the concrete specimens were subsequently tested for compressive strength, dynamic modulus of elasticity, and length and mass changes. The results show that the specimens exposed to sulphate attack exhibit higher strength and dynamic modulus than those kept in water. The length change is negligible and can be attributed to the normal swelling of concrete. On the other hand, concretes suffers mass loss and surface spalling and softening; the fine RHA-concrete results in a better resistance. For the accelerated sulphate attack method used in this study, mass change and visual monitoring are recommended for assessing the deterioration degree and the effectiveness of supplementary cementitious materials to resist sulphate attack.