Development of urban lands with various land use results in creation of different forms of the city, and this physical development cause traffic problems. High traffic volume more than capacity of urban systems, results in environmental problems, especially air and sound pollutions.
Air pollution due to traffic is one of the main concerns of urban planners and environmental administrators in developing countries for decades, because air pollution directly affects citizens’ health. This issue, in developed countries, has been solved through correct planning on land use and transportation, and emphasize on environment protection.
We will try, in this research, to examine the correlation between land use, traffic, and its effect on urban environment, especially on air quality. In other words, we will survey the effects of land use in physical movement due to traffic, and its effect on air quality.
Land use and transportation are two sides of a coin (…). On one hand, transportation is most important requirement of city development and, on the other hand, planned or unplanned development results in transportation needs. Hence, there is a very high correlation between transportation and land use.
Many analytical and descriptive models have been developed to show this correlation, each one provides one aspect of researches and explanatory elements in geometrical structure of city (…).
But correlation between transportation, land use and environmental parameters such as air pollution haven rarely examined. Although environmental problems, nowadays, are one of the most important problems, especially in metropolises, and these problems should be solved.
Rural regions, in developing countries, are urbanizing quickly, and cities are changing into metropolises, which cause environmental problems. Most common type of these problems is related to air pollution in cities. Air pollution could be result of industrial activities, transportation and other elements in cities, but according to JICA, more than 80% of Tehran’s pollution is result of urban transportation. Because of belonging of significant part of city (…… square meter equal to …… percent of district space) to highways and linkages in and around district 2, most of air pollution is created by moving vehicles in districts (…….).
Urban transportation is affected by three elements: 1- road and street, 2- vehicles and 3- users (citizens), so we should consider there three elements to reduce or eliminate air pollution due to transportation. These elements are shown in diagram number (….).
First, we should consider urban infrastructure, especially road and street, to reduce air pollution due to transportation. If our roads have high traffic capacity, vehicle could pass faster and air pollution will be reduced.
Although road widening is restricted by land limitations in cities, otherwise the city would changes into a giant parking place (this is what happened in Hemmat Highway in district 2 and its picture is represented in appendixes). Using the good materials for road constructing also could reduce pollutions due to tiny dusts scattered in space.
Second, utilizing planning and transportation administration, and using low pollutant vehicles would help better air quality.
Today, world is talking about bi-fuel, battery and solar automobiles, which make lesser pollution. Another way of air pollution reducing is also to promote the use of public transportation systems, which make lesser pollution per passenger, in comparison to personal vehicles. Also developing the green lines in cities for bicycles and encourage people to use them is another solution.
Third, modifying citizens and vehicle and road users travel pattern is another way. These would be achieved by reducing the need to travel by motor vehicles through development of electronic city and utilizing internet and intranet for routine daily works- nearest way to travel, development of public transportation fleet and encouraging people to replace their personal vehicles with public transpiration services. Planning of permanent land use could reduce air pollutions indirectly.
So we can say that there is a linear relation between transportation quality and land use in cities. City air pollution is most important problem, especially in big cities of developing countries. Source of this pollution is vehicles. Main city air pollutants are presented in table below:
Table- city air pollutants due to transportation
Effects of these pollutants on citizens life- city construction- human health and … have been proved (1234).
As mentioned above, main source of city air pollution is urban transportation which is influenced by citizens travel pattern and land use. Relationship between urban travel patterns, specification of origin-destination and land use will be achieved through mathematical analysis. Origin-destination distance will affect citizens travel pattern obviously. Long distance between residential and working areas, between origin and destination indeed, will affect transportation and energy usage. Even citizens’ economic status and relationship between public transport and personal vehicle usage will affect traffic volume in cities.
Transportation is needed because it eliminates distances by modifying relationship ability between various activities. Indeed, this close relationship between land use and transportation makes transportation equipments one of strongest especial geographical tools for planners, so they could utilize it for conduction of urban development.
However, land use and transportation relation is complicated and we can’t make any cause and effect relationship between them. For example, it’s obvious that modification of transportation infrastructure has clear affect on land use activities. Population volume and distribution of residential areas or industrial displacements, etc. change the transportation demand pattern. Thus, it’s necessary to prior goal in transportation planning be the development of effective balance between land use activities and potential capacity of their relationship, to reduce air pollution and enhance environment quality.
Land use pattern typically would identify by district selection and district location and relationship between districts and organizing various city zones such as commercial-official- internal and external (1234). ( )
There is multilateral interaction between various elements. These elements include land use intensity- traffic limitation level- vehicles effectiveness- centralizing level- urban form- cost of energy and orientation to various types of public transportation. All of these elements define city air quality and fuel consumption level.
According to Newman and Knorty (……..) there are various indexes for evaluation of correlation between transportation and land use, including:
land use intensity index
orientation to non-automobile transportation
traffic limitation level
centralizing level of urban form
public transportation performance
This study has been made according to these indexes.
As travel volume and its characteristics are under affect of land use intensity and nature, it seems gathering basic information about land use is first to do. Land use scales for residential areas, typically, do measure by pure residential aggregation. While in working centers and buying areas it does measure by rate of one person to appropriate occupation space. Required data could be provided by official sources and we could synchronize them by recourse to planning applications rules. These basic data have provided by surveying in every internal traffic zone.
People’s interest in public and private transportation, daily urban motor traffic volume, main street width, branches, proper usage of traffic signals and citizens’ attention to them are points that should be taken into account in land use and urban transportation systems’ survey.
However, most common transportation type is automobiles that occupy more than 20% of streets in many countries. And it shows that land use for transportation purposes is the second one after residential land use.
Environmental problems in cities have been changed into complex situation, all elements related to each other. Environmental stresses in cities are result of daily increase in city population and need to more space and changes in land use for better services. Observation in district 2 in Tehran shows that main environmental stress is result of enhance in traffic volume, especially in highways. It brings air and sound pollution problems. Other environmental problems also are challengeable in district 2, but we will emphasize on air pollution in this thesis.
Although Tehran’s district 2 is a developed one, but mentioned problems, especially traffic burden and air pollution decrease the quality of urban environment. Main reasons of vehicles congestion, which is main source of air pollution in district 2, are as below:
fast and unbalanced development of district
changes in form of the city and continual changes in land use
development of residential areas with high aggregation
economic development of city, which resulted in enhancement in citizens’ afford
Insufficient and inappropriate transportation system, which resulted in utilizing personal vehicles by citizens.
Rate of city streets length to personal vehicles
Vehicle parking beside streets
Excessive increase of highways in district, which changed district 2 into passage of other districts.
Insufficient administration of traffic and transportation.
Above reasons may help in increase of air quality problems and decrease of urban environmental quality.
It is long time that traffic throng is one of the main problems of Tehran. This throng in district 2 is more because of extent of passages and highways. This throng results in waste of many hours by citizens and millions of liters fuel too. Traffic may result in decrease of people property and dissatisfaction. Traffic also affects air quality and results in various commercial and hygienic detriments. Observations in district 2 show that traffic volume increases as the city develops. We need a strategic prevention method and utilized conventional methods were not effective yet.
Threats and opportunities, and weaknesses and strengths have been considered in strategic prevention method. If, as mentioned previously, traffic is most important element in air pollution, there are two methods for reduction of air pollution in cities:
First, by control and decrease of automobiles volume, traffic, and air pollution hence, will be reduced. Optimal traffic administration to provide roads capacity- traffic signals- infrastructure improvement and to provide public transportation system could be utilized to control number of automobiles. And urban environmental status will be improved by utilizing clean fuel like bi fuel natural gas or electronic fuel.
Second, a strategy related to urban planning and proper distribution of urban land use and decreasing urban travels are essential to solve the problem of urban air quality downfall, and show the importance and necessity of these surveys.
Most important purposes of this survey are:
Description of current land use characteristics in Tehran district 2, regarding zones- development- aggregation and continuity.
Description of relationship between citizens’ physical movement and land use plan and citizens’ decision making in vehicle selection.
Description of characteristics of air pollution in Tehran district 2, regarding sources- type of vehicles exhaust- adjustment and affects on urban environment
Description of some characteristics of land use policy tools- transportation and air quality in Tehran district 2, which has direct effect on making seasonal plans perpetual, and proposing related measures which could improve relationship between land use and physical movement and result in better urban air quality.
First hypothesis in this study is that there is relationship between air quality and land use plan through physical movement by motor vehicles. It is on the basis of fact that any traffic due to utilizing fossil fuel in automobiles results in emission of pollutants and hence results in air pollution. If automobiles do not emit air pollutant gases, like electric hybrid or solar automobiles, there will be no such relationships. But major urban transportation in district 2 is taking place by personal and motor vehicles now (………..).
Second hypothesis is that air pollution in district 2 is mostly result of motor vehicles and probably it’s true, because there is no other pollutant source like air pollutant factories in this district. We can make a clear relationship between traffic volume and number of air pollutants by this hypothesis. Since wind rate and direction, which makes emitted exhausts uncondensed, is not considered in measuring of air quality in streets, this relationship will not be completely realized. So may be emission volume will not be reported correctly. Yet there is a lack of recorded data about air quality measuring which causes some deployment because it reduces the quality of mentioned relationship. Anyhow it’s expected that this study provide basic method for more comprehensive study about transportation and environmental relationships in Tehran district 2.
Emission of various gases depends on fuel type and automobile age. But it is not possible to determine age of automobiles in motion and thus we will connivance it in traffic calculation.
Third hypothesis is that if scale of automobile’s motor will be considered, any automobile utilizing fossil fuel, regardless of age, emits exhaust, which has similar effect on environment.
This study only considers relationship between land use and physical movement through personal automobiles or public transportation systems. Indeed, variants such as migrants- urban transportations through public transportation systems- personal automobile owners, jobs and purpose of urban transportation that control physical movement. These variants have been considered in this study, but direct relation between some of them has been neglected. Actually, affects caused by transportation are not limited to air pollution, but include sound pollution and tremble, which have been neglected too, and we only emphasize on air pollution in this study.
Tehran, as capital of Iran, is located in natural bed between 3534 degree of north latitude and 51 to 5137 degree of east longitude. This bed is limited to northwest border of Markazi desert in south, to Jajrood valley in east, and valleys of Karaj in west. Regarding high extent and population (……), Tehran has been divided into 22 urban districts with independent municipality to better administration.
Tehran district 2 is placed in 51’20’ degree east longitude and 35’45 degree north latitude. It’s placed in south skirt of Alborz Mountains. It’s limited to south skirt of Alborz Mountain in north, alluvial desert of Markazi in south, and Farahzad and Evin Darakeh watercourses in east and west. Its total shape is as a rectangular with 12 kilometers in north-south direction and 4 kilometers in east-west direction, including 5000 hectare space. South part of it in Tehran desert has hot and dry climate, while north part in Alborz Mountains skirt has more temperate climate. General slope is in north-south direction varying form 30-40 degrees in north part to gentler slope of 5-10 degrees in south part. Alborz Mountains is in its north. Its most high place is about 1800 meter higher than sea level, with medial slope of 30-50 degrees. There are some small valleys like Darakeh, Farahzad in Mountains skirt (north of Tehran). There are many hills in centric part, results of water erosion. Highest place in these hills is about 1500 meter higher than sea level. Medial slope in top of the hills are 20-30 degrees and in skirt about 30-40 degrees. These hills are differentiated from other topographic zones by their height, multiple valleys and severe slopes in skirts. Pardisan Park hills and north of Kooye Nasr hills are some of them. This district ends in 1200 alignment in south. Tehran district 2 is limited to Alborz Mountains in north, districts 1, 3, 6 in east, districts 9, 10, 11 in south and district 5 in west. District is totally in north of Tehran and Aborz mountain skirt and most of it is at least 1400 meter higher than sea level.
Why district 2 has selected for study?
Because district 2 had experimented intensive changes in land use in recent years . Most of Tehran’s highways are placed in this district and it’s a good choice because of its extent from center to north of the city. District 2 includes 10% of population and space of Tehran.
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