A THEORETICAL OVERVIEW OF ROAD HUMP EFFECTS ON TRAFFIC SPEED IN RESIDENTIAL ENVIRONMENTS <s> INTRODUCTION <s> Motorization trend has been rising rapidly in many countries including Malaysia. But the level and trend of motorization in each country varies according to major factors such as population, size of the country, economic growth, income level, fuel cost, and public policy on vehicle ownership. The level of motorization has both positive and negative impacts. On the positive side, it provides mobility from a landuse to another landuse to meet various purposes besides increasing trade related to transportation. On the negative side, it increases pressure on the environment by increasing more pollutants into the atmosphere causing global warming, traffic congestion, accidents, and added pressure on the road and rail infrastructure in terms of capacity. Looking at the past trend of motorization, the future appears very bleak. This paper highlights trends and causes of motorization in the past, its likely impact on the environment and possible implications. <s> BIB001 </s> A THEORETICAL OVERVIEW OF ROAD HUMP EFFECTS ON TRAFFIC SPEED IN RESIDENTIAL ENVIRONMENTS <s> INTRODUCTION <s> A speed limit of 30 kilometres per hour (km/h) has been widely introduced for urban residential streets to ensure traffic safety and allow these streets to fulfil other intended functions. However, excessive speeds on these roads are very common, causing traffic safety problems and threatening the liveability of neighbourhoods. An effective and active way to deal with speeding is the application of a performance-based design approach, as mentioned in previous research. In a performance-based design approach, street geometrics and roadside elements are selected based on their influence on the desired driving speeds. The relationship between driving speeds and street features therefore needs to be determined. Although several studies have developed operating speed models for urban streets, all of these models were calibrated based on data for streets with speed limits of more than 30 km/h. The present research is designed to investigate the influence of various roadway and roadside characteristics on operating speeds on urban tangent street sections with a 30 km/h speed limit using profile-speed data. A simultaneous equation regression with a three-stage-least-square (3SLS) estimator was used for the modelling effort. The driving speed models developed in this study incorporate several street design factors, which provide helpful information for urban planners and street designers to cope with speeding issues on residential streets. <s> BIB002 </s> A THEORETICAL OVERVIEW OF ROAD HUMP EFFECTS ON TRAFFIC SPEED IN RESIDENTIAL ENVIRONMENTS <s> INTRODUCTION <s> In 2010, the City of Edmonton reduced the posted speed limit (PSL) in six residential communities from 50 to 40 km/h. This study investigates the impact of the reduced PSL on vehicle speeds using a before-and-after experimental design with a control group adjustment. Continuous speed and traffic flow data was collected at 65 locations over a period of 7 months, with the first month representing the before period and the following 6 months representing the after period. Speed evaluation was performed on several levels, ranging from individual speed survey locations to an overall aggregate analysis. Several performance indicators, such as mean free-flow speed, speed variance, level of compliance, and percentile speed profile, were considered. The results revealed a statistically significant reduction in mean free-flow speed and speed variances for all combinations of time-of-day and day-of-week classifications. Though absolute compliance to the reduced PSL was low, compliance to a 15 km/h threshold above the PSL was significantly high. Moreover, the analysis showed that the effectiveness of the reduced PSL improved with time. Language: en <s> BIB003
In Malaysia, the substantial increase in the rate of motorization, with a growth rate averaging 8.16% for Kuala Lumpur and 6.73% for Malaysia from 2000 to 2004 has caused serious concerns on the road infrastructure BIB001 ). This increasing rate of motorization has subsequently led to concerns on traffic congestion, environmental pollution and road safety. In addition, the rising motorization rate has also resulted in increased road infrastructure. Some of the additional road infrastructure may be constructed in close proximity to residential areas; together with the increase in the number of on-road vehicles, this can raise more concerns on the residential living environment in terms of traffic volume, speed and noise. The occurrence of excessive vehicle speeds is found to be relatively common along local and collector roads with low speed limits BIB002 BIB003 , leading to concerns where increased traffic volume and speed have caused the deterioration of living conditions   . These common occurrences of increased vehicle speeds have also been found to cause an increase in accident severity, where the probability of pedestrians receiving fatal injuries when hit by a car is 3.5% at 15 mph (24.1 km/h), 37% at 30 mph (48 km/h) and increases to 83% at 44 mph (70.8 km/h) (Limpert, 1994 as cited by Abdul  . As one of the traffic calming measures, road humps have helped to significantly reduce the speed of the moving vehicles especially along residential roads. Due to its largely positive impact in its ability to considerably reduce vehicle speed, its importance has been growing over the years in improving the living environment of the residential areas. However, a prevailing issue in Malaysia is that the Malaysian Traffic Calming Guidelines has not been adhered to in the installation of various existing traffic calming schemes in Malaysian residential areas. This may lead to various issues such as a lack of standardization in dimensions, unsuitable locations, user confusion due to improper construction and no effect on driver behaviour  . As part of an ongoing research to analyse the effects of road humps in improving the living environment, the objective of this study was to understand the prevailing theories concerning the effects of road humps on traffic speed and also identify the research gaps for the ongoing research to improve upon.