Cars or motorbikes? Which are to blame for traffic jams in Vietnam?

The challenge lies in managing different types of vehicles like cars and motorbikes and their effect on traffic and road use.

In most cities in the world the high cost of land makes road widening nearly impossible, and so authorities instead encourage people to use public transport and discourage the use of private vehicles.

In Vietnam, people debate whether motorbikes or cars are the main cause of traffic jams.

Those who blame motorbikes say their drivers often stop or swerve without warning and ignore lanes and safety distances. Often they even drive on the wrong side of the road.

But others say cars are larger and have a wider turning radius, which makes them incompatible with urban infrastructure. Car drivers also frequently reverse improperly, park recklessly or drive in the wrong direction.

I have seen many arguments and accidents involving both vehicles, with their users blaming each other for congestion.

Driver awareness is certainly important. But setting aside this factor, which vehicle has a greater negative impact on traffic planning?

The answer is not just about road space. It also involves speed, lane distribution and safety distances.

In western countries, the answer is clearer.

At high speeds, all vehicles must maintain safe distances between each other. In such cases, motorbikes end up requiring as much road space as cars, despite their smaller size.

Since people in western countries often drive long distances in various traffic conditions, they tend to prefer cars for safety, especially to survive possible high-speed collisions.

Motorbike use is relatively low and mostly limited to enthusiasts or short trips in densely populated areas.

In Vietnam, the answer might be different.

At average urban speeds, motorbikes can transport people some 40% more efficiently than cars in terms of movement and road space utilization though cars have higher top speeds. This advantage disappears when both vehicles are at full capacity—cars typically carry four people while motorbikes carry two.

But in reality, I have observed and noticed that the average number of people on a car or a motorbike is similar—1.49 for cars and 1.45 for motorbikes. This means that, despite cars having the capacity to carry more passengers, most car owners prefer to drive alone. As a result, cars end up taking much more road space than motorbikes while transporting the same number of people.

Heavy traffic jam in Hanoi. Photo by VnExpress/Ngoc Thanh

On uncongested roads with smooth traffic flow, motorbikes are nearly twice as efficient as cars. In congested conditions, cars become physical barriers, occupying at least four times the road space of motorbikes and worsening the congestion.

Hanoi thus experiences severe traffic jams whenever it rains as people switch to cars or hail taxis. Poor visibility in the rain and road conditions reduce speed and worsen the congestion.

Some drivers blame motorbikes for slowing traffic, arguing that banning them would allow cars to maintain higher speeds even in bad weather.

This argument is only partly true.

Vietnam's narrow sidewalks and buildings situated right by the side of roads mean cars still need to slow down in bad weather.

I ran simulations at an intersection with traffic lights with 200 people and different vehicles in free-flowing conditions.

Motorbikes took an average of 2:59 minutes to pass while cars took 8:08 minutes.

On narrow roads with sharp turns, cars took even longer.

The lack of parking space forces cars to park on sidewalks and roadsides, worsening congestion.

When a vehicle stops on a two-lane road, it creates a bottleneck. Cars worsen this situation by blocking a larger portion of the road and reducing traffic flow 11 times more than motorbikes.

This makes cars the bigger cause of traffic congestion under current conditions.

Despite this many countries still prioritize car-friendly infrastructure because cars come with built-in safety features.

In Australia's Queensland State, motorbikes make up only 2.6% of registered vehicles but account for 32% of traffic-related hospitalizations.

Cars made up 60.5% of registrations but account for only 25% of hospitalizations.

I’m not writing this article to argue for banning cars or motorbikes. Instead, I want to highlight the traffic characteristics of different vehicle types and call on car drivers to be more patient, responsible and considerate toward motorcyclists.

Cars are equipped with more safety features but also occupy significantly more road space than motorbikes. A single mistake by a car driver can lead to traffic congestion 11 times worse than that caused by a motorbike.

Clearly, there will be no effective solution to Vietnam’s traffic problems without improving driver awareness, reducing the use of private vehicles and expanding public transport infrastructure.

These solutions will take a lot of time and investment.

*To Thuc is a lecturer at James Cook University in Australia.