While writing my book about Hanoi, I wondered what made this city so attractive. The "livable city" rankings are often based on criteria such as quality schools, clean air or low crime rates. But I always thought there was something else in Hanoi, more difficult to measure, I named it "lively sidewalk".

I am sure many visitors to Hanoi will agree with me. And those who buy vegetables at the toad market in the morning, take children and pets for a walk in the day, or eat and go out for dinner in the evening will agree.

There are many reasons why sidewalks here are full of life. The French urban design in the city center includes beautiful tree-lined streets with pedestrian space. The cramped housing makes people like to go out. And Vietnamese food is so delicious that no one wants to miss the opportunity to eat pho in the morning, or bun cha in the afternoon.

For all these reasons, I am really excited that the Hanoi urban government plants a lot of trees throughout the city, following the French urban design tradition. I am also assured that the sidewalk economy, the restaurants, the friendship and the love continue to flourish on the sidewalks of Hanoi.

However, sometimes I am worried. Recently, Nghi Tam Street was upgraded according to the explanation to help traffic flow. And this makes perfect sense. But in the process, sidewalks were minimized and all greenery was removed. I understand that Au Co Street may soon suffer the same fate.

Nghi Tam and Au Co are one of the main roads connecting the airport to the city center. They are the first image of Hanoi welcoming heads of state and other important people to Vietnam. The narrow and tidy, empty, green pavement of these roads will make a sad first impression.

The justification for cutting down trees, narrowing sidewalks and widening the streets is understandable: there are too many vehicles on the road and traffic congestion is becoming unbearable. If the road surface area increases, traffic will be more smooth, congestion will be reduced.

Many cities in advanced economies faced increased traffic congestion during the 20th century, and their answers were often the same: paving the way.

In New York, master builder Robert Moses once wanted to run a highway through Soho, one of the most valuable neighborhoods in the city. In Paris, under President Georges Pompidou, a beautiful bank of the Seine River was deformed to be ugly to build the highway on it.

However, urban planners soon realized that more roads attracted more traffic and did not reduce congestion much. This unsettling result was recorded in the US as early as 1930. Since then, transportation experts have understood the problem.

Why doesn't the wider street cause less traffic? Imagine that every morning, 100,000 vehicles travel from the suburbs to the city center and there are ten equally wide streets for people to take this journey. Road users constantly choose the least congested roads, the result of this choice is that the traffic flow is evenly spread across all roads. With 100,000 vehicles and 10 equally wide streets, each road will have about 10,000 vehicles in the morning.

Now suppose that one of these streets doubles the width. As a result, road users faced a choice between the surface equivalent of 11 old roads: 9 of them were as narrow as before and 1 was twice as wide. The result: 9,091 vehicles on the old roads (100,000 divided by 11), down 9%. But on the extended street, there are currently 18,182 vehicles every morning (9,091 times 2), up to 82%.

The reality is a bit more complicated than this example. Larger road surfaces may cause some people to move from public transport to motorcycles or private cars. At that time, the number of vehicles on the road may be more than 100,000.

With so many roads built or expanded in cities over the years, there is now enough statistical evidence to assess their impact. Following a 10% increase in road surface, after a few years, it was found that the number of vehicles increased by 9% to 10%.

These findings are the basis for a bold initiative of the city of Seoul. The acclaimed Cheonggyecheon project involves demolishing a very busy highway that cuts through the city center, reviving the buried river below and turning the area into a beautiful, long urban park. 11 km. When the project was announced in 2003, there were concerns that congestion would become unbearable. But in fact, the traffic flow has decreased almost proportionately.

The only sustainable solution to urban congestion is efficient public transport thanks to fast bus routes and especially the metro. Bartering sidewalks for traffic is a way to ease congestion in the immediate future, but the benefits are temporary. And the loss of lively sidewalks, one of Hanoi's largest urban assets, will be permanent. Just as the Hanoi urban government is committed to planting more trees, I hope they will also make efforts to protect the wide sidewalks for Hanoians to gather, sell, buy, eat, and meet friends. friends and nurture love.

In fact, I can only encourage the Hanoi urban government to follow the example of Seoul. If you notice, you will notice that some lanes of Nghi Tam Street are larger than the others. If the larger lanes are cut to the size of the smaller lanes, the sidewalk may be enlarged and trees may be replanted. And this does not affect traffic at all.

Martin Rama