Simulation model of traffic operations on single carriageway roads: Model calibrationand validation

The current Malaysian procedure for a detailed evaluation of the capacity and effects of various road and traffic characteristics for single carriageway roads, which is adopted directly from the American Highway Capacity Manual, is inadequate and inaccurate since several aspects used in the method such as the consideration of the recreational vehicles and trucks are not directly applicable to the Malaysian traffic characteristics. The validity of the analysis is debatable since the way in which the effect of motorcycles on overall performance of the roadways is considered is not clear. The existing simulation models of traffic operations on single carriageway roads also suffer from a similar weakness. Therefore, there is a need to develop a comprehensive traffic simulation model to carry out this task. Such a model must be capable of simulating traffic behavior for a range of road layout and geometry, at junctions and compositions of traffic which include motorcycles. This paper describes the development of a simulation model of traffic operations on single carriageway roads to assess and evaluate the speed/flow relationships and hence the road capacity from the simulation model for a given road geometry and traffic demand

Automated pavement imaging program (APIP) for pavement cracks classification and quantification – a photogrammetric approach

The evaluation of pavement conditions is an important part of pavement management. Traditionally, pavement condition data are gathered by human inspectors who walk or drive along the road to assess the distresses and subsequently produce report sheets. This visual survey method is not only time consuming and costly but more importantly it compromises the safety of the field personnel. With an automated digital image processing technique, however, pavement distress analysis can be conducted in a swifter and safer manner. Pavement distresses are captured on images which are later automatically analysed. Furthermore, the automated method can improve the objectivity, accuracy, and consistency of the distress survey data. This research is aimed at the development of an Automated Pavement Imaging Program (APIP) for evaluating pavement distress condition. The digital image processing program enables longitudinal, transverse, and alligator cracking to be classified. Subsequently, the program will automatically estimate the crack intensity which can be used for rating pavement distress severity. Advancement in digital photogrammetric technology creates an opportunity to overcome some problems associated with the manual methods. It can provide a low-cost, near real time geometrical imaging through digital photogrammetry without physically touching the surface being measured. Moreover, digital photogrammetry workstation (DPW) is user-friendly, less tedious and enables surface conditions to be represented as ortho-image, overlay contour with ortho-image, as well as digital elevation model. The algorithms developed in this study are found to be capable of identifying type of cracking and its severity level with an accuracy of about 90% when compared to the traditional method. This is to show that the combination of the photogrammetric approach and APIP is a viable system to be used in pavement evaluations

Estimating average daily traffic using alternative method for single carriageway road in Southern Region Malaysia

Average Annual Daily Traffic (AADT) and Average Daily Traffic (ADT) are two parameters that are commonly required by traffic engineers and road designers to design and analyse the traffic operational performance of a road segment. In Malaysia, ADT is normally used to forecast the volume of traffic in the design year as well as to design the pavement thickness. Basically, ADT can be generated using expansion factor estimates from Peak Hour Volume (PHV). Current practice in Malaysia uses an expansion of 10% to estimate ADT from PHV. This paper discusses the results of a study carried out to establish a model for estimating ADT using PHV for single carriageway road. The 24-hours traffic data were collected at 9 sites in the districts of Johor, Malaysia for the period of 14 days. The 7-days data were used to establish the model and the other 7-days data were used to validate the model. For validation purposes, the absolute percent error (APE) for each estimate of ADT obtained from the model was calculated and compared with observed ADT. The statistical test at 95% confidence level was conducted to determine the significance difference between the ADT from actual data and the estimate ADT from model. The result shows that a power-formed trend line (y=axb) suits to the observed data with the coefficient of determination of about 0.90. Validation result shows that the ADT for the model has lesser APE compared with the ADT estimated using the factoring approach. A comparison of both estimated and actual ADT values using t-Test shows that there is no significant difference between the estimated ADT using models and the actual ADT. However, the ADT estimated using the expansion factor of 10% shows the vice versa. Such a finding implies that the model obtained from this study predicts ADT accurately than the current practice

Calibration of microsimulation model for tight urban diamond interchange under heterogeneous traffic

Traffic simulation models have been widely used to evaluate design alternatives and to help decision-makers to select best design option for prevailing traffic conditions. This study focuses on application of microsimulation model to the performance assessment of Tight Urban Diamond Interchange (TUDI) located in a congested urban setting with population more than 9 million and current transport demand up to 13.5 million daily motorized trips. Geometric and operational data was collected by conducting multiple site visits. Traffic volume data showed the heterogeneous nature of traffic. Microsimulation model; VISSIM was applied and appropriateness of this model and the proposed methodology was assessed based on maximum queue length as Measure of Effectiveness (MOE)

Performance of autonomous vehicles in mixed traffic under different demand conditions

Autonomous Vehicles (AVs) are considered one of the potential solutions to future urban mobility with several promised benefits regarding safety and traffic operation. Despite of expected benefits, these vehicles will take decades to have full market penetration and before that, AVs will co-exist with Conventional Vehicles (CVs), which may affect the performance of AVs owing to different driving logic than CVs. The aim of this study is to quantify the impacts of varying penetrations of AVs when introduced in mixed traffic conditions. The study employed simulation environment VISSIM to study the different scenarios based on the percentage of AVs in mixed traffic, category of AVs and varying demand levels. The findings show that at lower demand levels (1000 veh/hr and 2000 veh/hr), CVs and three categories of AVs produced similar results. However, cautious and normal AVs negatively affect traffic operations when the demand level is increased. At demand-3 (3000 veh/hr), the penetration rates of cautious AVs greater than 50% shows negative impact on performance. At demand-4 (4000 veh/hr), even a small proportion (25%) of cautious AVs can negatively affect performance, and a similar effect is observed for normal AVs with a penetration rate greater than 75%. For speed, the minimum reduction with the increase in demand is observed for aggressive AVs, followed by conventional vehicles, normal AVs and cautious AVs. It can be concluded that the aggressive AVs produced better delays, queue length, speed and conflicts than CVs, cautious AVs and normal AVs at the highest demand levels

Drivers behaviour on expressways: headway and speed relationships

This paper describes result of a study on driver's car following behaviour on Malaysian high-speed highways. Drivers' car following behaviour can considered as one of the main factors that causes road accidents to occur such as rear end collision between vehicles on highways. The aim of the study was to examine the safe following distance adopted by drivers on expressways at various operating speeds. An automatic traffic recording device attached with pneumatic tubes was used to record traffic movement at three selected expressway segments in Malaysia for six consecutive days. More than one hundred thirty three thousand (133,000) headway and speed data were involved in the analysis. The distance headway and associated speed collected were classified into five vehicle following categories by vehicle type, i.e. all vehicles, car following car, car following heavy goods vehicle (HGV), HGV following HGV, and HGV following car. Linear regression models were used to develop relationship between distance headway and speed. The relationships developed can be regarded as reliable since the R2-values for each of the relationships is in the range of 0.80 to 0.99 and can be used to estimate a safe following distance perceived by a driver at a given speed. The driver's average response time on an expressway is 3.06 sec which is 1.9 sec longer than those who are driving on a two-lane single-carriageway road. Such a variation in response time indicates that the level of aggressiveness of drivers on a two-lane single-carriageway road are higher than the drivers on an expressway

Properties of bitumen modified with latex

A lot of effort has been made to improve the base bitumen properties by adding different types of modifier. The current issue of pavement failure has raised a concern that high specification of bitumen is essential to counter the asphalt pavement challenges. This is to ensure that the bitumen could perform better as a road material. Natural rubber, particularly latex, has potential to be used as a modifier in bitumen compared to other types of rubber as it is cheaper, accessible and easily dispersed in the liquid bitumen when heated. This study evaluates the physical and rheological properties of the bitumen when added with latex rubber. Difference percentages of latex i.e. 2.5%, 5.0%, 7.5% and 10% were added to the 60/70 PEN bitumen and tested for penetration, softening point, viscosity, ductility, loss on heating and dynamic shear rheometer tests. As a result of the modification, it was found that latex hardened the control bitumen, increases the viscosity and provides better resistance against rutting

Transportation mode choice binary logit model: a case study for Johor Bahru city

The mode choice stage in transportation planning is the analysis process to estimate the number or percentage of trips performed by each mode of transport. In practice, the number of trips is used to estimate the demand for each mode of transport. Such information is important for planning and designing transportation facilities in an urban area. A mathematical model of individuals' mode choice is usually required in such an analysis. This paper discusses the result of a study carried out to evaluate the attributes that influence the mode choice of transport in Johor Bahru city by interviewing the individuals living for more than one year in the study area. The investigation conducted through one of attitudinal survey techniques known as stated preference survey. Stated preference survey conducted on a random sample of 384 respondents. Investigated attributes have been identified in analysis stage by applying binary logistic regression analysis procedure before deriving binary logit model for individuals' mode choice of transport in Johor Bahru city. Based on stated preference survey and logistic regression analysis of data, the model of mode choice of transport in Johor Bahru has been derived and attributes of age, income, vehicle ownership, comfort of car, reliability of bus service, affective motives and instrumental motives were found statistically correlated to the mode choice of transport in Johor Bahru

Performance of rutting, stripping and cracking of warm mix asphalt

Hot Mix Asphalt (HMA) is a conventional mixtures and widely used in Malaysia. Emissions of Carbon Dioxide (CO2) during production of HMA due to high temperature give bad impact to the environment. During construction, cool weather is one of the factor that will easily influence the HMA mixtures where it will cause the reduction of temperature during compaction. This factor will affect the compaction process for the pavement which the most important part for road construction. It will reduce the density of the pavement and also the strength which cause shorter life span, rutting, cracking and stripping. Therefore, in this study, Warm Mix Asphalt (WMA) is one of the methods to overcome these issues. This study investigated the performance WMA in term of rutting, cracking and stripping incorporating different percentages of additives namely Evotherm (ET) and Evoflex (EF) with 0.3%, 0.4% and 0.5% by weight of bitumen. These additives were used to lower the mixing and compaction temperature of asphalt mixture. Asphalt mixture with nominal maximum aggregate size 14 mm (AC 14) with 5.3% optimum bitumen content were used in this study. The optimum additive content was evaluated based on the Marshall, Modified Lottman, Indirect Tensile Strength (ITS), and Asphalt Pavement Analyser (APA) tests. The results revealed that 0.4 % ET and 0.3 % EF additives were considered as optimum additive content. Both 0.4 % ET and 0.3 % EF gave better performance in stripping and rutting resistance. However, in cracking performance, 0.4 % ET was more susceptible in cracking compared with 0.3 % EF

Performance evaluation of asphalt micro surfacing - A review

In spite the fact that micro surfacing receives accolades by researchers of being the most cost-effective, environmentally friendly, and functionally viable pavement preventive maintenance amongst the various asphalt surface treatments (AST). However, there has not been a universally standardised mix design, acceptable material type, compatible polymer-binder combination, laboratory-field correlational performance tests, and its field dependency performance indicators. The requirements set by the International Slurry Surfacing Association (ISSA), Malaysian Jabatan Kerja Raya (JKR-public works department) and American Society for Testing and Materials (ASTM) are stated to be guides. This study brings to fore the challenges, methodologies adopted and successes recorded towards solving the aforementioned concerns by various researches globally from existing literatures with emphasis on material-type effects, mix design methodology, serviceability/environmental performance, incorporation of industrial wastes and emulsion-polymer compatibility amongst others in micro surfacing. Hence, the contents of relevant published journal articles, theses, academic and industrial reports published within the last two decades (1979 - 2019) that met the selection criteria aforementioned were critiqued. Result indicated improvement in key pavement surface functional performance parameters as a function of enhanced polymer(s) used in improving desired performance, type of aggregate and its gradation, pre-treatment condition and ultimately emulsion type. However, there is a lack of total consensus on the mix design, even though polymers are unanimously agreed by researchers to improve performance. Future advances in micro surfacing should focus on the use of industrial wastes, synthetic material and especially by-products from industrial processes