Sidewalks and traffic: a false trade-off

By Martin Rama   July 29, 2019 | 11:24 pm PT
When I was writing my book "Hanoi Promenade," I often wondered what makes the city so special, so attaching.
Martin Rama

Martin Rama

Livability rankings for cities are often based on criteria such as quality schools, or clean air, or low crime... But I always thought that there was something else about Hanoi, something more difficult to measure. If I had to put a name on that something it would be "lively sidewalks."

I am sure that many of the tourists who visit Hanoi would agree with me. And the Hanoians who buy their vegetables in street markets in the morning, take their children and pets out for a walk during the day, or get together to eat, drink and date outdoors in the evening, would also agree.

There are many reasons why sidewalks are so full of life in Hanoi. The French urban layout of the city center includes beautiful tree-lined streets, with ample space for pedestrians. Crowded housing encourages people to go out. And Vietnamese food is so good that nobody wants to miss on the chance of a street pho in the morning, or a street bun cha at night.

For all these reasons, I feel truly heartened to see the urban authorities of Hanoi planting so many trees throughout the city, following the tradition of the old French urban layout. I am also reassured that informal markets, food stalls, friendship and love continue to thrive on Hanoi’s sidewalks, despite the declared intention to make them "neat."

However, there are also times when I get worried. Recently, Nghi Tam road was upgraded, in a way that helps traffic flow. And that makes perfect sense. But in the process the sidewalks were narrowed to the bare minimum, and all trees were removed. I understand that Au Co road may soon suffer the same fate.

Nghi Tam and Au Co road are one of the main axes to travel from the airport to the city center. They are the first image of Hanoi that will welcome heads of state and other important personalities visiting Vietnam. Their narrow and sterile sidewalks, without a tree, will produce a sad first impression.

The justification to cull trees, narrow sidewalks and widen streets is understandable: there are too many vehicles on the road, and traffic congestion is becoming unbearable. If road surface increases, traffic will flow more smoothly, and congestion will be eased.

People sit at a tea shop on the sidewalk of Hanoi, April 2019. Photo by VnExpress/Nguyen Chi Nam.

People sit and chat on a sidewalk in Hanoi, April 2019. Photo by VnExpress/Nguyen Chi Nam.

Cities in advanced economies faced surging congestion throughout the 20th century, and their answer was often the same. In New York, "master builder" Robert Moses wanted to run highways through Soho, one the city’s most valuable neighborhoods today. In Paris, under president Georges Pompidou, the beautiful right bank of the Seine River was defaced to build a highway on it.

However, urban planners soon realized that more roads attracted more traffic and did not ease congestion much. This disturbing result was noted in the U.S. as early as 1930. Since then, transportation experts have studied the problem, and they understand it much better.

An example can help explain why wider streets are not less congested. Imagine that every morning 100,000 vehicles travel from a suburb to downtown, and that there are 10 streets of similar width allowing to make this journey. Travelers constantly choose the least congested ones, and as a result of their choices traffic spreads evenly across all of them. With 100,000 vehicles and 10 similar streets, there are roughly 10,000 vehicles taking on each of them every morning.

Now suppose that one of these streets doubles in width. As a result, travelers are confronted with the choice between the equivalent of 11 streets: nine of them narrow as before, and one twice as wide. The result is 9,091 vehicles per street-equivalent (=100,000/11), a 9 percent reduction. But in the widened street there are now 18,182 vehicles every morning (=9,091x2), an 82 percent increase!

The real problem is a bit more complex than in this example. The greater road surface available may induce some travelers to shift from public transportation to private motorbikes and cars. If so, the number of vehicles on the road could be much more than 100,000.

With so many roads built or widened in cities over the years, there is by now enough statistical evidence to assess their impact. And the consensus is clear: a 10 percent increase in road surface is followed, a few years later, by a 9 to 10 percent increase in the number of vehicles in circulation.

Another assessment of the relationship between road surface and vehicles in circulation comes from accidents that have disabled part of the transportation network. Earthquakes in Japan, the collapse of an elevated highway in New York or the burning of a bridge in Rouen (France) have not led to increased congestion but rather reduced the number of vehicles on the road almost proportionally.

These findings underlie a bold initiative by the city of Seoul. The acclaimed Cheonggyecheon project involved demolishing a very busy highway that cut through the city center, recovering the river that had been buried underneath, and converting the area into a beautiful urban park, 11 kilometers long. When the project was announced, in 2003, there were fears that congestion would become unbearable. But traffic fell almost proportionately, as modern transport analysis would have predicted.

The only durable solution to urban congestion is efficient public transportation, under the form of rapid bus lines and especially metro lines. Losing sidewalks to traffic may relieve congestion for some time, but the gain will be temporary. However, the loss of the sidewalks will be permanent, and lively sidewalks are one of Hanoi’s greatest urban assets.

Much the same as urban authorities are planting trees in the tradition of the old French layout, I hope they will also make every effort to protect wide sidewalks, allowing Hanoians to get together there to shop, eat, meet friends and nurture love.

In fact, I can only encourage the urban authorities of Hanoi to follow Seoul’s example. If you pay attention, you will notice that some of the traffic lanes of Nghi Tam road are larger than the rest. If these lanes were "cut" to normal size, sidewalks could be widened and trees could be planted again. And this, without affecting traffic at all.

*Martin Rama is the Chief Economist for Latin America and the Caribbean at the World Bank and a Project Director at the Center for Sustainable Urban Development, under the Vietnamese Academy of Social Sciences. The opinions expressed are his own.

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