Analysis of Motorcycle Microscopic Characteristics at Roundabouts: Under mixed traffic condition in Vietnam
Researcher/Author
August - 2021
Even for mid-blocks or crossroads,
mixed traffic is a complex system.
Due to the numerous interactions between vehicles moving in various directions, possessing a variety of characteristics and renouncing lane discipline, mixed traffic at roundabouts constitutes an extremely complex situation. They stand in for an intersection that is not signalized and makes use of the yield on entry and circulation rules.
This gap was filled in the current study by examining the microscopic properties of vehicles from a individual perspective. The two major goals were to describe the special traits of mixed traffic in Vietnam (a case study) and to reveal the minute details of motorbikes at roundabouts.
The status of traffic in industrialized countries is frequently referred to as homogeneous traffic. Two key criteria are included in this definition: cars are the most common type of vehicle and drivers maintain lane discipline. Homogeneous traffic conditions are described as "traffic movement under fairly homogeneous traffic conditions with cars constituting roughly 80% or more of the vehicles display lane discipline" by Arasan and Krishnamurthy (2008). The movement of all vehicles on the road is synchronized when they abide by the lane standards.
The traffic situation is more complicated in developing countries, though. Chaos has resulted from the expansion of vehicle types and adjustments to performance standards. Dimensions (such as lateral and longitudinal size) and performance capabilities (such as acceleration, deceleration, intended speed, and manoeuvrability) of vehicles differ. By ignoring the lane rule, many smaller than a car types of vehicles can enjoy additional freedom in their lateral movement. Small vehicles can maximize their utility by taking advantage of the advantages of static and dynamic characteristics to fill open space on the road surface.
According to Lee (2007), this approach causes behaviors including filtering, swerving or weaving, tailgating, oblique following, and maintaining a smaller headway when aligning with the lateral edge of the vehicle in front of you. In the end, this traffic stream causes movement that is not coordinated.
Constitution of mixed traffic
Bicycles, motorbikes, and cars all occupy the same road area, which is how heterogeneous traffic is conceptualized. Vietnam's Hanoi and Ho Chi Minh (HCM) City, where motorcyclists make up more than 80% of transportation, were the subject of a traffic study by Minh et al. in 2007. It is highlighted that there should be enough motorbike volume in the mixed traffic.In more recent times, mixed traffic has been described as having inconsistent lane markings and a range of vehicle characteristics.
Following lane discipline can be challenging due to considerable variances in vehicle size and speed. To maximize their utility, small vehicles frequently occupy all available space on the road.
High-performing vehicles encounter significant opposition from low-performing ones, making it impossible to estimate the entire stream. As a result, numerous distinct behaviors have been found in studies of mixed traffic, including overtaking, swerving, vehicle filtering, crawling, cutting-tail, giving way, accumulation and dispersion at crossings, and many others, as identified by Trinh et al (2018).
Shiomi et al. (2012) analyzed the differences between passenger cars and motorcycles in terms of field of vision, size, weight, maneuvering techniques, turning radius, acceleration, and deceleration. They also described the characteristics of traffic flow dominated by motorcycles free from lane restrictions.
Motorcycle microscopic characteristics at roundabouts
As depicted in the photo below, the roundabout has six entry and exit legs and is circular in shape. The inscribed circle and the central island each have diameters of 51.7 and 15.2 meters, respectively. Because there are no lane markers, cars are free to maneuver inside the circle. The "give-way" rule, which forces drivers to yield to traffic already in the roundabout, is mandated by national driving regulations. Traffic is also required to move in a counterclockwise circular manner. Regarding the number of legs, its design is typical for roundabouts in HCM City.
In developing nations, roundabouts are typically employed in places where junctions with more than five legs are required because of the limited space in metropolitan areas and the limited infrastructure investment for multilevel intersection choices. Additionally, this design is recommended to increase the effectiveness of the same-pave-area multi-leg intersection.
Additionally, it serves as one of the primary road networks' links. The circular roundabout connects three four-lane arterial highways with two-way traffic and four-lane widths. These legs most likely have comparable widths, lane counts, intersection angles, and traffic flow. The roundabout can be thought of as a three-lane roundabout and has the benefit of allowing a wide circulating road width. This offers plenty of room for motorcyclists to utilize their mobility, making the behavior anticipated in the study likely to take place.
Motorcycles are lightweight and have a high power-to-weight ratio. They can readily accelerate or brake because of this, which causes them to constantly change their speed. Lower speeds mean that less deceleration is needed to halt in the same amount of time. Furthermore, mobility is greater at lower speeds, giving the driver more time to react.
Drivers favor soft braking at roundabouts over hard braking as a result. The changing movement direction within the immediate frame of reference is represented by the turning angle. It is the angle between the current and previous traveling directions, not the steering angle of the handle or the front wheels.
About Saigon Motomobile....
Vietnam already has a whopping 20 million motorcycles on the road, and the market continues to expand by 2 million units year, giving the country possibly the highest per capita motorcycle ownership rate in the world. As a result, motorbikes have come to be associated with Vietnamese cities and have even influenced the country's culture and history.
The Road as Social Space
John Urry has described the car as “a domestic, cocooned, moving capsule, an iron bubble”. The automobile allows a shell of private space to be extended out into the public realm, insulating passengers from physical and social contact with the world around them.
This is the ultimate social privilege in a setting where public spaces are contaminated by pollution, dust, precipitation, danger, and rudeness, so it is not unexpected that there is currently a vehicle craze in Vietnam.I do see, though, that the Vietnamese people I know who own automobiles have kept their motorbikes for those occasions when they need to get somewhere fast or just to ride for fun. In comparison to riding a motorcycle, urban car travel is even less predictable in terms of journey time, and a car cannot replicate the impression of agility and dynamism that riding a motorbike in a Vietnamese city gives. The car is an inherently asocial form of transportation, whereas a low-speed motorbike in a crowd is quite opposite.
Like the walker but unlike the automobile driver, the urban motorcyclist is immersed in her environment, and her whole body is visible, unshielded by a windscreen. Without getting off her bike, she can turn to greet the person sitting next to her, pull into a roadside stall, or stop in front of a friend's house and talk to someone in the living room. Motorcyclists “đi vòng vòng” Mon Sundays for the sheer joy of the sensation, it even becomes possible to pick up members of the opposite sex while moto-strolling. I would contend that even the tarmac is a "social" environment, despite the fact that the roads in Vietnam are undoubtedly incredibly hazardous and inhumane in many respects.
Vietnamese traffic is not rule-governed like traffic in the developed world. Instead, it is a constant social negotiation whereby unspoken understandings and eye contact are used to negotiate right of way and safety. While walking in big Vietnamese cities might be intimidating, one gets the impression that they have a place on the road and that it is possible to blindly enter the traffic without looking while yet having their presence in the middle of it acknowledged. Contrarily, if one did this in the Anglo-American traffic culture, they ran a much higher chance of getting run over by a car who couldn't understand a pedestrian's right to be in the traffic zone.
Decals and Delinquency
Unquestionably, in modern Vietnam, riding a motorbike is a sign of social standing. Piaggios and Vespas are at the top of a convoluted but widely accepted hierarchy of brands and specs, while so-called "Chinese" bikes are at the bottom. While older or lesser status bikes are taken to a backstage area, the most desirable bikes will be positioned by the valets directly on the sidewalk outside chic cafes and bars. Additionally, their owners suffer since they must wait longer to have them recovered when they depart.
Businesses that have sprung up to meet this need specifically allow those who cannot afford the new high status models to "improve" their old bikes by adding new-style fairings, stickers, and color schemes to them. These false claims of rank, which are in any event obvious to the people they are intended to impress, have a poignant quality. However, this practice unequivocally shows how, in contemporary Vietnam, social prestige and transportation are directly related. It also demonstrates how a culture of constant improvement has replaced the post-war era's mentality of scarcity and recycling. Even if something continues to function flawlessly, it will quickly "degrade" [xuống cấp] and lose status in today's Vietnam if it is not modernized.
You know what's sad?
I lost my Bibliography list for this article. So take the information as you will...