Assessment of delays at roundabout

Traffic delay is the additional travel time that experienced by a road user beyond what would reasonably be desired for a given trip. It is also a standard parameter that used to measure the performance of an intersection. This study concerns with the delay experienced by the drivers at a roundabout. The main objective is to evaluate the applicability of the existing theoretical delay models to estimate delays. Data pertaining to the analysis of delay was collected at a conventional roundabout in a sub-urban area. The t-test were conducted. The result shows that the observed delay at a conventional roundabout can be estimated using Akcelik & Troutbecks theory as there is no significant different between both observed and theoretical delay at 95% confident level. Whereas the observed delay has significant different if compared with theoretical delay estimated using Kimber & Hollis theory and CETUR formula. On the other hand, all of the theoretical and observed delay at the roundabout falls in the LOS A. However, more data are required in order to validate the result of this study

Midblock U–turn facilities on multilane divided highways: an assessment of driver’s merging gap and stop delays

This paper discusses the results of a study which was carried out with a primary objective to evaluate the merging gaps and traffic delays at midblock U–turn facilities installed on multilane divided highways. A total of more than 2,000 U–turn drivers at a midblock U–turn facility on an urban multilane highway were observed using a camera–video recording technique. The data pertaining to the analysis of gap acceptance and rejection was abstracted from the video–playbacks using a computer event recording program. The analysis found that the critical gap of the drivers at a midblock U–turn facility is in the range of 4.0 – 4.5 seconds, which is different from the values reported for studies carried out in other countries. The effect of major road traffic volumes on the stop delays to the U–turn drivers could not be established because the data did not exhibit any specific trend. The drivers were observed to make forced merging maneuvers when traffic volumes in the main traffic stream are relatively heavy. Such maneuvers lead to flow breakdown in the major road to occur at a faster rate. The findings suggest that there is a need for a thorough study to be carried out to evaluate the current practice of U–turn facility design and assessment methods since traffic operations at such a facility is different from those at on–ramp facilities where their planning and design are generally based on the American Highway Capacity Manual

Permeability in Malaysian hot mix asphalt mixtures

Many studies have shown that the air void content affect the permeability of the hot mix asphalt (HMA) mixtures. This study aims to evaluate the characteristic of local HMA mixtures and find a relationship between air void and permeability, and then obtain in-situ minimum density level in order to produce impermeable pavements. Eight types of HMA mixes were produced; ACW14, ACW20, BMW14, BMW20, ACB28, BMB28, BMR28 and BML10. Ten samples for each mix with different compactive efforts; 75, 60, 50, 40 and 30 were prepared. The permeability test was conducted to get the coefficient of permeability. From the test conducted the permeability versus air void content graphs were plotted. The relationship between permeability and air void content is directly related. As the air void content increased the permeability also increased. Therefore, it is suggested that the maximum in-place air void contents for wearing course, ACW14 and ACW20 are 6.4 and 4.2% or 98 and 100% of Marshall density design at 4% air void respectively while the air void contents for wearing course, BMW14 and BMW20 are 5.4 and 6.0% or 99 and 98% of Marshall density. For binder course, ACB28 and BMB28, 6.4 and 6.1% air void contents or 98% of Marshall density are recommended. For levelling, BML10 and bituminous roadbase, BMR28 course, 12.9 and 7.2% air void content or 91 and 97% of Marshall density are proposed respectivel

An alternative method of estimating space-mean speed

Average travelling speed usually applied in the traffic analysis as required in the fundamental traffic model. As one type of speed under the space-mean speed, most of the researchers have derived the equation to estimate the space-mean speed. There are a few factors that influence the speed changes along the segment. The fluctuate speed along the segment give an idea to average the spot mean speed from at least two points in order to estimate the space-mean speed. This paper explores an alternative method on how to convert the time-mean speed to space-mean speed that can represent the actual operating speed along segment using the average technique. A total of 18 data sets of time-mean speed and space-mean speed in six segments of uninterrupted two-lane single carriageway road were collected using automatic traffic counter and moving car observer, respectively. Two sets of automatic traffic counter were installed along the segment to record the spot speed and then converted to the time-mean speed, while the moving car observer were conducted concurrently to get the space-mean speed. The data sets were analysed using linear regression analysis. The results of summary of model show a strong relationship with coefficient of determination, R2=0.808, while ANOVA test results show the coefficient of constant and time-mean speed is not zero with p-value is less than 0.05 at confident level of 95%. The error obtained from this alternative equation are lesser than the established equation and it recommends that the alternative equation is acceptabl

Speed limit: to what extent it is obeyed?

Seeks to establish close working relationship with the world automotive associates within the Southeast Asia region as well as in the Asia Pacific region. Road safety is a growing challenge globally – and an even more pressing issue for developing countries especially among ASEAN countries. The key road safety problem in ASEAN countries is motorcycle safety. Thus, with the theme ‘Addressing the Bottom Billions’ this conference is further focus on seeking solutions for solving motorcycle safety problems as vulnerable road user

Speed–flow–geometry relationships and capacity for two–lane single carriageway roads

The current Malaysian practice in road capacity analysis, Malaysian Highway Capacity Manual 2011 (MHCM) is based on a method adopted from the Highway Capacity Manual(HCM) of the United States. All the analysis elements appear to be taken directly from the manual. The rationale for using such a method for Malaysian conditions is not well defined. This paper deliberates the background of the methodology used in the development of speed, flow and geometry relationships and the capacity for single carriageway roads. A microscopic traffic simulation model which is capable of simulating traffic operations on single carriageway roads for a range of road geometry configurations and traffic flow conditions was developed and used to evaluate the potential capacity of a single carriageway road. The results of the analysis indicate that a two-lane single carriageway road is capable of accommodating traffic flow higher than the values derived from the previous HCM. The current version of the HCM also appears to underestimate the vehicles’ travel speed for a range of traffic flows when compared with the results of the simulation model. The MHCM 2011, on the other hand, estimated travel speeds higher than the travels speeds predicted by both the HCM 2010 and simulation model. It shows that there is a different interpretation of LOS F in term of speed between HCM 2010 and MHCM 2011