Ahmad Farhan Mohd Sadullah

Exploring the effects of roadway characteristics on the frequency and severity of head-on crashes: Case studies from Malaysian Federal Roads

Head-on crashes are among the most severe collision types and of great concern to road safety authorities. Therefore, it justifies more efforts to reduce both the frequency and severity of this collision type. To this end, it is necessary to first identify factors associating with the crash occurrence. This can be done by developing crash prediction models that relate crash outcomes to a set of contributing factors. This study intends to identify the factors affecting both the frequency and severity of head-on crashes that occurred on 448 segments of five federal roads in Malaysia. Data on road characteristics and crash history were collected on the study segments during a 4-year period between 2007 and 2010. The frequency of head-on crashes were fitted by developing and comparing seven count-data models including Poisson, standard negative binomial (NB), random-effect negative binomial, hurdle Poisson, hurdle negative binomial, zero-inflated Poisson, and zero-inflated negative binomial models. To model crash severity, a random-effect generalized ordered probit model (REGOPM) was used given a head-on crash had occurred. With respect to the crash frequency, the random-effect negative binomial (RENB) model was found to outperform the other models according to goodness of fit measures. Based on the results of the model, the variables horizontal curvature, terrain type, heavy-vehicle traffic, and access points were found to be positively related to the frequency of head-on crashes, while posted speed limit and shoulder width decreased the crash frequency. With regard to the crash severity, the results of REGOPM showed that horizontal curvature, paved shoulder width, terrain type, and side friction were associated with more severe crashes, whereas land use, access points, and presence of median reduced the probability of severe crashes. Based on the results of this study, some potential countermeasures were proposed to minimize the risk of head-on crashes.

The effect of motorcycle helmet type, components and fixation status on facial injury in Klang Valley, Malaysia: a case control study.

BackgroundThe effectiveness of helmets in reducing the risk of severe head injury in motorcyclists who were involved in a crash is well established. There is limited evidence however, regarding the extent to which helmets protect riders from facial injuries. The objective of this study was to determine the effect of helmet type, components and fixation status on the risk of facial injuries among Malaysian motorcyclists.Method755 injured motorcyclists were recruited over a 12-month period in 2010–2011 in southern Klang Valley, Malaysia in this case control study. Of the 755 injured motorcyclists, 391participants (51.8%) sustained facial injuries (cases) while 364 (48.2%) participants were without facial injury (control). The outcomes of interest were facial injury and location of facial injury (i.e. upper, middle and lower face injuries). A binary logistic regression was conducted to examine the association between helmet characteristics and the outcomes, taking into account potential confounders such as age, riding position, alcohol and illicit substance use, type of colliding vehicle and type of collision. Helmet fixation was defined as the position of the helmet during the crash whether it was still secured on the head or had been dislodged.ResultsHelmet fixation was shown to have a greater effect on facial injury outcome than helmet type. Increased odds of adverse outcome was observed for the non-fixed helmet compared to the fixed helmet with adjusted odds ratio (AOR) = 2.10 (95% CI 1.41- 3.13) for facial injury; AOR = 6.64 (95% CI 3.71-11.91) for upper face injury; AOR = 5.36 (95% CI 3.05-9.44) for middle face injury; and AOR = 2.00 (95% CI 1.22-3.26) for lower face injury. Motorcyclists with visor damage were shown with AOR = 5.48 (95% CI 1.46-20.57) to have facial injuries compared to those with an undamaged visor.ConclusionsA helmet of any type that is properly worn and remains fixed on the head throughout a crash will provide some form of protection against facial injury. Visor damage is a significant contributing factor for facial injury. These findings are discussed with reference to implications for policy and initiatives addressing helmet use and wearing behaviors.

Evaluating the effects of road geometry, environment, and traffic volume on rollover crashes

There are a number of factors that cause motor vehicles to rollover. However, the impacts of roadway characteristics on rollover crashes have rarely been addressed in the literature. This study aims to apply a set of crash prediction models in order to estimate the number of rollovers as a function of road geometry, the environment, and traffic conditions. To this end, seven count-data models, including Poisson (PM), negative binomial (NB), heterogeneous negative binomial (HTNB), zero-inflated Poisson (ZIP), zero-inflated negative binomial (ZINB), hurdle Poisson (HP), and hurdle negative binomial (HNB) models, were developed and compared using crash data collected on 448 segments of Malaysian federal roads. The results showed that the HTNB was the best-fit model among the others to model the frequency of rollovers. The variables Light-Vehicle Traffic (LVT), horizontal curvature, access points, speed limit, and centreline median were positively associated with the crash frequency, while UnPaved Shoulder Width (UPSW) and Heavy-Vehicle Traffic (HVT) were found to have the opposite effect. The findings of this study suggest that rollovers could potentially be reduced by developing road safety countermeasures, such as access management of driveways, straightening sharp horizontal curves, widening shoulder width, better design of centreline medians, and posting lower speed limits and warning signs in areas with higher rollover tendency.

Framework for developing a spatial walkability index (SWI) for the light-rail transit (LRT) stations in Kuala Lumpur city centre using analytical network process (ANP) and GIS

In support to the nation’s goal of developing a liveable city, Malaysian government aims to improve the mobility in Kuala Lumpur by providing good quality transit services across the city. However, the public starts to demand for more than just a connectivity between two points. They want their transit journey to be comfortable and pleasant from the very first mile. The key here is the first and last mile (FLM) of the transit service which defines their journey to access the station itself. The question is, does the existing transit services’ FLM satisfy public’s needs? Therefore, many studies had emerged in attempt to assess the pedestrian-friendliness. While most of them did base on the pedestrian’s perceptions, there were also studies that spatially measured the connectivity and accessibility to various landuses and point of interests. While both can be a good method, their integration could actually produce a better assessment. However, till date, only a few studies had attempted to do so. This paper proposes a framework to develop a Spatial Walkability Index (SWI) by integrating a multicriteria evaluation technique, Analytical Network Process (ANP) and network analysis on geographical information system (GIS) platform. First, ANP will aggregate the degree of importance for each walkability criteria based on the pedestrian’s perceptions. Then, the network analysis will use the weighted criteria as attributes to find the walkable routes within half mile radius from each station. The index will be calculated by rationing the total length of walkable routes in respect to the available footpath. The final outcome is a percentage of walkable FLM transit routes for each station which will be named as the SWI. It is expected that the developed framework can be applied in other cities across the globe. It can also be improvised to suit the demand and purpose there.In support to the nation’s goal of developing a liveable city, Malaysian government aims to improve the mobility in Kuala Lumpur by providing good quality transit services across the city. However, the public starts to demand for more than just a connectivity between two points. They want their transit journey to be comfortable and pleasant from the very first mile. The key here is the first and last mile (FLM) of the transit service which defines their journey to access the station itself. The question is, does the existing transit services’ FLM satisfy public’s needs? Therefore, many studies had emerged in attempt to assess the pedestrian-friendliness. While most of them did base on the pedestrian’s perceptions, there were also studies that spatially measured the connectivity and accessibility to various landuses and point of interests. While both can be a good method, their integration could actually produce a better assessment. However, till date, only a few studies had attempted to do so. This paper ...

Pedestrian-attractiveness score for the first/last mile transit route using spatial data collected with a mobile positioning application

Transit services or public transportation is expected to be able to not only provide a good mobility and accessibility to people in a city, but it should allow a pleasant journey to them to attract people to ride it. It can be influenced by the presence of built environments such as the pedestrian facilities and furniture along the walking route. Therefore, many studies have attempted to measure the attractiveness of the first/last mile (FLM) transit journey, however, there seem to be limitations in those studies. First, there is a lack of pedestrian data available. This could affect the precision of measuring the pedestrian attractiveness. Second, there is a lack of studies implementing such data to analyze the pedestrian-attractiveness itself. This paper proposes a framework combining spatial data collection for pedestrian data with spatial analysis to measure the pedestrian-attractiveness of the FLM transit journey. It will utilize the mobile positioning procedure to collect the data as it is the most efficient method to collect thousands of pedestrian data on the ground in a short amount of time. It uses a mobile mapping application available on the market to collect data in the field. The collected spatial data will then be used as attributes in the spatial analysis of the pedestrian routes of the FLM transit journey. The outcome of the framework will be a score indicating the pedestrian-attractiveness of the FLM transit journey. The results show that the pedestrian-attractiveness score can be influenced by the number of built environments present along the walking route and public preferences of these. A station with a higher number of built environments will score more than the other. Similarly, a station with a more preferred parameters will also score higher.

Effect of Roadside Development on the Safety of Intersections without Signals

Roadside development plays an important role in the safety of the entire road in general and intersections in particular. Illegal and improper buildouts such as roadside kiosks, bus stops and fire stations are an accident hazard and a hindrance towards sustainable development. This paper presents the first account of analysis of safety evaluation of intersections with respect to roadside development in Malaysia. The data collected on 14 sites was analyzed. The results indicated that the bus stops and restaurants located right infront of the unsignalized intersections were the major contributory factors in decreasing the safety. Moreover it was found that facilities staggered away from the intersection such as another access point are less hazardous. It is recommended that relevant authorities should ensure the removal of such risky roadside developments.

The Alternative Trip Generation Model for Flat/Apartment/Condominium and Low Cost Housing Subcategories

Malaysian Trip Generation Manual (MTGM) is an important document to assist transport planners in forecasting the estimated trip attraction and trip production from a land use. The forecast is crucial in estimating trip generation from a proposed development on the existing road network. Therefore, this study is to verify the accuracy of the existing trip generation model published in MTGM for flat/apartment/condominium and low cost housing subcategories. By applying variable transformation, four alternative models were developed. They were the logarithmic model, the inverse model, the linear-logarithmic model and the logarithmic-linear model. Using residual analysis, influential data was identified and taken out for second analysis. Model selection was based on R2 value, t-test and Kolmogorov-Smirnov test results. Besides linear model, logarithmic model is also truly representing trip generation model for both subcategories. There is some difference in the trip generation estimation between the study model and the existing model in MTGM. Sensitivity analysis shows the level of sensitivity between study model and existing linear model. One of the implications in using the studied trip generation model is in evaluating level of service of the junction.

Modeling Pedestrian Behavior in Rail Transit Terminal

This paper concerns a review of the existing research in pedestrian behavior in rail transit terminal. A comprehensive review of the existing method and model are looking at the parameters of the pedestrian behavior and flow in relation to the pedestrian interaction and evacuation planning in rail transit terminal. It is shown in the review that a lack of an overall and detailed consideration of pedestrian behavior studies along the area of rail transit terminal in Malaysia. The necessity to integrate transportation engineering and pedestrian model is important where it will be a start to an upcoming research related to a development of safety management system of pedestrian in term of evacuation strategies and performances in rail transit. This can be a reference point for the traffic engineer to design walking infrastructures for many other public transit areas in Malaysia.