Traffic congestion [Unreasonable housing structure: the fourth major cause of traffic congestion]

In terms of cost and resource utilization efficiency, suburbs should be low-density houses, and suburbanization is the suburbanization of the rich, not the suburbanization of the poor. Such a public choice is to maximize both private efficiency and public efficiency.

In the previous article, I analyzed three reasons that lead to traffic congestion in China's cities, namely, excessive dispersion of suburban population leads to excessive amplification of traffic flow, unreasonable traffic network structure greatly reduces traffic operation efficiency, and bus priority is mistaken for bus priority, which greatly reduces the traffic efficiency of public transportation. Here, I want to focus on the analysis of the fourth major cause of traffic congestion in China: unreasonable housing structure. This problem is mainly reflected in two aspects: low housing density in the city center and unreasonable housing layout structure.

The housing density in the city center is too low.

Urban planners in China generally mistakenly believe that the high population density in the central city is the main cause of traffic problems, so the main measures in policy and planning are to reduce the population density in the central city as much as possible and transfer the population to the suburbs on a large scale. Therefore, "spreading cakes" has become the main feature of urbanization or urban construction in China. This model is the main problem of urban planning and development in China. It not only occupies scarce land resources excessively, but also leads to the high investment cost of urban public enterprises. The more fundamental problem is that it greatly increases people's traffic distance, over-magnifies traffic flow, makes most people move and a few people don't, resulting in a large number of ineffective traffic flow increases. In the case of low family car penetration rate (low car ownership), traffic congestion is very serious. How do city governments at all levels do this? To sum up, there are three ways:

First, control the floor area ratio of urban housing, and reduce the spatial density of housing by reducing the average building height of housing. China is a country with a large population and few land, and the development direction of urbanization in China must be the orientation of big cities. From the perspective of saving land, we should take more relaxed measures than most countries in the world to limit the floor area ratio and deal with the serious shortage of land resources by increasing the housing density. But unfortunately, we have adopted the strictest floor area ratio limit in the world. In the central city of many cities in China, except CBD, the plot ratio is usually controlled at 2 ~ 3 times, while in big cities like Japan, South Korea and many developed countries, the plot ratio is much higher than ours, reaching 5 ~ 6 times or even higher. We see Manhattan in new york, USA. Whether it is an office building or a residence, the average floor is as high as 40 ~ 50 floors, as are Tokyo, Seoul and Hong Kong. When you stand on the streets of Manhattan, you can see everything.

Many people only see the disadvantages of the over-dense or crowded housing structure in these cities, but they don't see the advantages of saving land and improving the efficiency of urban economic operation. In modern society, the latter is more important, and the quality of life of urban people must be based on efficient traffic operation and convenient daily life. Keeping most residents in the city center and reducing the traffic flow (especially reducing the serious asymmetric traffic flow at work) is the basis of improving traffic efficiency, and the most important way is to increase the housing density. High-density traffic in the city center is mainly solved by public transportation, which is mainly subway, supplemented by buses, walking and bicycles.

The second is to reduce the plane density of housing through unreasonable greening rate requirements. Comparing the big cities in China with those in the world, we will find that the urban greening rate in China is the highest. Is the high greening rate related to traffic efficiency? Yes, it matters a lot. We should think about it: Why is there almost no greening in the downtown areas of big cities in the United States? This is the case in Manhattan. Apart from Central Park, there are few trees in Manhattan, and there are no large areas of grass. The same is true of Tokyo and Hong Kong. Don't people in western developed countries like greening and pay no attention to the ecological environment? If a big city pursues greening, especially high greening rate, it will reduce the efficiency of the city from two aspects: on the one hand, it will waste valuable land resources. In the central city, the land is "an inch of land and gold" and "flowing water of gold and silver". Large-scale or large-scale greening will inevitably greatly reduce the economic benefits of the land. On the other hand, improving urban greening rate means that the plane density of houses and road area will be significantly reduced, the plane space of the city will be expanded, and the traffic distance will be increased, thus reducing traffic efficiency.

Our city planning department has formulated the requirement of 35% green area between buildings. This requirement of average green space rate not only means reducing land utilization rate and traffic efficiency, but also leads to the problem of high greening management cost. Many old communities in urban centers are afforested over and over again, and the grass planted will soon disappear, and the trees planted will eventually be sparse. The reason is that the management cost is too high, and the new residential area is beautiful because the residents are rich. We advocate the concept of overall greening, that is, adopting centralized greening to improve the greening rate of cities. The improvement of greening rate can be concentrated in parks or green belts in suburbs, outer suburbs and urban areas, rather than evenly distributing green spaces in buildings and indoors. In order to improve the housing density, we must reduce greening and build fewer squares, especially fewer big squares.

The third way to lead to low housing density in urban areas is to "demolish without moving". The policy of low compensation and not moving back has forced many residents (many of them are low-and middle-income groups) to move to the suburbs, thus greatly reducing the housing density in the central city.

Unreasonable housing layout

Increasing the housing density in the central city and keeping most people in the urban area is an effective way to reduce traffic flow and solve the traffic congestion problem, but if the housing layout is seriously unreasonable, it will obviously affect the efficiency of this method. To sum up, there are three unreasonable housing layout problems that affect the efficiency of urban traffic operation in China.

First, too many closed communities have been built in urban and suburban areas, which have divided roads, seriously damaged the road network structure and reduced the traffic smoothness. In the past planned economy era, there was a problem of unreasonable housing layout, that is, government agencies or state-owned enterprises implemented the mode of integration of work and housing, forming a large closed management area, separated from the surrounding roads. With the development of the commercial housing market, this situation has been obviously broken and replaced by the housing community model. A community, surrounded by several small buildings and dozens of buildings, forms an independent community, covering hundreds of acres or even hundreds of acres. This greatly reduces the efficiency of social transportation from two aspects: on the one hand, due to its closure, external vehicles are forbidden to pass and can only bypass, which leads to the privatization of roads in this area and the waste of traffic resources, thus making the available "public" roads seriously insufficient. If it is a completely open residential area, there is no such problem. On the other hand, the living mode of closed residential quarters leads to a large number of broken roads, so many public roads are interrupted or suspended, and the systematic road network structure is seriously damaged.

Second, the reversal of urban rules has hindered the formation of a reasonable road network structure. We lack a highly stable (rigid or legally mandatory) "background" planning in urban planning. In developed countries, this background planning is the road network construction planning, and all other planning is based on it. Road planning is the main planning and housing planning is the secondary planning. Housing planning takes road planning as the "background", that is, houses are gradually filled in the planned road network structure. If there is a "road", you should build a house by the way. If there is no "road", we must make up the "road" according to the requirements of "background" planning, and then build houses according to the "road" without destroying the road network structure. This is science.

However, many urban planning in China adopts the opposite principle, with housing as the center, real estate developers leading urban planning, roads being passively built to adapt to housing, and houses being built wherever they go. It leads to the division of road network and the failure to form a reasonable road network structure. On this basis, what kind of house should we build, namely residence, shopping mall or office building? In addition to supporting public construction, it is mainly decided by real estate developers according to the market. In urban planning and management, we only take care of these functions that should not be taken care of, but the management that really ensures the rationality and integrity of road network construction has been seriously ignored.

Thirdly, there is a strange phenomenon in the overall housing layout of our city, that is, while the housing and population density in urban areas are too low, the housing density and population density in some suburbs are very high, such as Huilongguan and Tiantongyuan, large residential areas built in Beijing. This is also an important housing structure problem, which has a great influence on the efficiency of the transportation system. Where are the traffic jams in Huilongguan and Tiantongyuan? Obviously, it is not blocked in the mega-community (the road network structure of the mega-community is also unreasonable), but mainly blocked in the import and export of the mega-community and the import and export of the central area and suburbs of the whole city. It is caused by a large number of people going to work in the city or going home to sleep ("sleeping in the city" is an appropriate description of these communities), which is a negative effect of reducing the housing density in the city center. Because it is an absolute majority of residents (80%), then it is still necessary to rely on high density to solve their housing problems.

Since high-density housing is inevitable for residents, where should high-density housing be built to achieve the highest overall efficiency of the city? Considering the traffic efficiency, the residents' burden and the city government's burden, there is no doubt that high-density housing will be built in the city center. An extended question is, where should affordable housing or affordable housing be built? The answer is the city center, not the suburbs. In terms of cost and resource utilization efficiency, suburbs should be low-density houses, and suburbanization is the suburbanization of the rich, not the suburbanization of the poor. Such a public choice is to maximize both private efficiency and public efficiency. Therefore, the poor in developed countries live in the city center, which is why we should re-evaluate the socio-economic role of slums.