The Science of Flow

Junction redesign and new overpasses are easing traffic congestion in Vietnam


With increasing numbers of vehicles on the road, getting from A to B in Vietnam’s major cities requires striking a balance between two things: tenacity and patience. Traffic jams are commonplace, and during rush hour the flow of traffic can often grind to a halt. Growing congestion is increasing commute time, and without a metro system, commuters have no choice but to take to the roads and wait.


Although the country continues to pour cash into infrastructure projects to ease the excess — Hanoi, for instance, increased their allotment for their urban traffic project to US$460 million (VND9.66 trillion) earlier this year — the question remains: how does Vietnam get things flowing? Is the solution to build more roads?


More Options, More Trouble


New research from the University of Toronto shows that increasing the number of roads in a major city only expands the demand for more. By studying traffic flow and infrastructure in a selection of American metropolises, researchers found that people drive more when the number of roads increases. So, by spending money on new thoroughfares, drivers will follow suit: with new roads comes new vehicles to fill them. You only need to look at the increased traffic over the last 12 months on Mai Chi Tho, the road leading to Thu Thiem Tunnel, to see how a freshly opened route can quickly attract growing numbers of vehicles.


So if building more roads doesn’t necessarily ease congestion, what’s to be done about the streets that are already there? The answer lies in the science of speed. For drivers in Vietnam, speed is often made impossible by the obstructions in their path — crossing pedestrians, merging cars and motorbikes, badly kept roads or busy junctions. While constantly applying the brake may be bothersome, the slowing effect may actually be part of the answer, which has been demonstrated by a change of road layout at one major intersection in the UK.


Junctions and Overpasses


Located in Poynton in northwest England, the Fountain Place junction overhaul relied on maintaining flow. Designers replaced traffic lights at the intersection with two flat roundabouts, and narrowed entrance roads from two lanes to one. Skeptical town residents soon found that the perceived ‘obstruction’ of the roundabout and the narrower entrances were enough to slow traffic to a steady flow, eliminating the halting effect of signals and keeping traffic moving consistently through the junction.


The redesign kept the intersection safer for pedestrians and vehicles, and shifted the assumption that traffic signals were essential to avoid chaos. A similar theory has been increasingly employed in Hanoi. Lights at previous bottleneck junctions — take for example the Daewoo Hotel junction at Kim Ma, Lieu Giai and Nguyen Chi Thanh — have been replaced by a one-way system. The traffic has slowed but importantly, like in Poynton, it keeps moving.


Ho Chi Minh City is also heading in a promising direction. By building new overpasses around the city the authorities are easing traffic flow at busy crossroads. They are also separating two and four-wheeled vehicles, thus keeping motorists safer.


Only the future will tell if the traffic woes in Vietnam are soon to be a thing of the past. But there is certainly some promise. Who knows, Vietnam may soon be at the forefront of traffic infrastructure, and leaders in harnessing the science of flow. — Karen Hewell

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