Managing Air Pollution with Urban Transportation

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Updated: Oct 19, 2023
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An exploration of how urban transportation strategies can be restructured to mitigate air pollution. The essay will discuss the benefits of public transportation, electric vehicles, and city planning initiatives that prioritize eco-friendly transport modes. On PapersOwl, there’s also a selection of free essay templates associated with Air Pollution topic.

Category: Air Pollution
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Pages:  9
Words:  2669
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Abstract: The recent economic expansion along with the population growth experienced in developing countries has had a big impact on the development of large cities like Delhi, India. Accompanied by Delhi’s rapid spatial growth over the last 25 years, urban sprawl has been contributing to increased travel. The vehicle fleet projected at current growth rates will result in more than 13 million vehicles in Delhi in 2020. Planning and managing such a rapidly growing transport sector will be a big challenge. Choices made now will have impacts lasting well into the middle of this century.

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With such rapid transport growth rates, automobile emissions have become the fastest increasing source of urban air pollution. In India most urban areas, including Delhi, already have major air pollution problems that could be greatly exacerbated if growth of the transport sector is managed unwisely. The transport plans designed to meet such large increases in travel demand will have to emphasize the movement of people not vehicles for a sustainable transportation system.

Therefore, the mathematical model developed here estimates the optimal transportation mix to meet this projected passenger km demand, while satisfying environmental goals, reducing congestion levels, improving system and fuel efficiencies through exploiting a variety of policy options at the minimum overall cost or maximum welfare from transport. The results suggest that buses will continue to satisfy most of passenger transport in the coming decades, so planning done in accordance with improving bus operations is crucial. INTRODUCTION: India is the world’s seventh largest country in areal extent with 2.2% of global land and the world’s second most populous country with more than 1 billion population. With a rapid economic expansion and population growth and a high rate of urbanization, planning and managing transportation systems has become a serious challenge. The total number of vehicles in India increased by more than 11 times from 1970 to 1990, approaching 21 million vehicles. The number of vehicles per 1000 people has increased from 3.4 to 25.31 in the same period, with previously given estimates of reaching 43 vehicles per 1000 people in 2000 (1).

The number of registered vehicles has maintained its increasing trend with a growth from 25.2 millions in 1993 to 33.85 millions in 1996, 37.23 millions in 1997 and to an estimated vehicle fleet of over 50 million vehicles in 2001 (2). This accelerated growth of the transportation sector in India will have the greatest impact on large cities where development is occurring in a fast and imperfect form. India is claimed to have 1% of world’s vehicles (3) and most of these vehicles are located in urban centers. Automobile emissions are the most rapidly growing source of urban air pollution in most of these developing cities. These emissions contribute to a disproportionate amount of exposures and therefore result in very high health damages. Hence it is much more cost-effective to control vehicular emissions rather than industrial emissions in urban areas (4). This paper, therefore, focuses on urban transportation planning for air quality management at a macro level with Delhi as the case study. Delhi has the largest vehicle population in the country with close to 3 million vehicles in 2000. The number of vehicles has grown very rapidly in the past 3 decades, the fleet has become 15 times bigger in this time period. The total number of vehicles per 1000 people in 1998 was 238. This number is estimated to reach 305 vehicles per 1000 people in 2005 (5). As the number of motor vehicles kept increasing the number of trips and distances traveled per trip have also increased with motorized passenger trips rising and cutting into bicycles’ share of passenger trips.

The transportation system is very inefficient with mostly personal vehicles – cars and two wheelers – that have mainly single occupancies (6). Cities in developing countries usually allocate 10-15% of their total land area for roads compared to 15-30% in cities in industrialized countries (20-25% in European cities). Delhi has 23% of its land area as roads. Although Delhi has one of the highest per capita road lengths and lowest number of vehicles per unit road length when compared with large cities around the world due to its large road network, it is still the most congested city in India (7). Delhi has the highest road length in India (26,379km of total length in 1998/1999), and its roads, if modern traffic management is applied, could accommodate 2-3 times the existing number of vehicles (5). In international comparisons of urban population density versus per capita length of urban roads (8), Delhi remains an outlier. Therefore, in order to reduce traffic congestion in Delhi, the use of well-designed traffic management control options are essential, and they will provide Delhi with a relatively quick and easy reduction in congestion levels. In this study of urban transport, which is one part of a project on transportation and environment at Harvard University, two different methodologies, simulation and optimization, are used to model the future vehicle fleet growth and the resulting vehicular air pollution in Delhi. The results from these applications will also be later linked to a GIS for Delhi for a visual representation and the evaluation of the effects of land use changes on air quality.


Transport planning is very important in the continued growth of the economy of a country. It should be carried out very carefully because there are many options to choose from and compare, the investments are very large, projects are very long lasting, and once committed to one there is no easy way of going back. A good transport plan should, after going through the steps of travel surveys and data collection, consider all the alternatives, transport management strategies, and policies for transport development that can be used in meeting the forecasted demands. There are two major ways of reducing adverse environmental impacts of the transportation sector: reducing the emissions per kilometer driven and reducing the amount of travel (vehicle km traveled – VKT). There are many different ways of achieving both of these objectives. Emission factors (g/km) are affected by a variety of parameters: fuel efficiency, traffic flow, speed, driver behavior, temperature, fuel characteristics, age, and maintenance levels of the vehicles. There are numerous ways of reducing these emissions per kilometer driven: emission standards for new vehicles, emission control devices, improving fuel quality, decreasing vehicle retirement ages, improving maintenance standards, using clean fuels and better engine design technologies (alternative fuel vehicles, new and clean vehicle technologies), flextime working hours, and managing the existing street space to maximize available capacity.

There are also various ways of enforcing the reduction of VKT: traffic demand and supply management options which include vehicle ownership and use controls, encouraging ridesharing, telecommuting, building roads, improving public transit, providing park and ride facilities, pricing options (road pricing, parking pricing, vehicle fees, fuel taxes), area licensing, land use management, change of modal split, road segmentation for buses, bicycles, and other vehicles. Other options such as increased quality of pedestrian environment in suburban zones has been found to decrease vehicle miles traveled. All these measures should be considered carefully because of the interactions they have among each other and while improving one they can worsen the effects of another. For example increasing vehicle prices will decrease vehicle registrations (i.e. the number of vehicles) but also will increase the vehicle life which will increase emissions per kilometer driven. Increasing fuel prices on the other hand will result in a win-win situation because it will decrease vehicle use and will also increase fuel efficiency because people would want to buy more fuel efficient vehicles. Also, benefits obtained by some control options could be in the short run only. For example, half of the time saved from improvements in speed has been found to be used for further travel. Finally, new capacity attracts new demand, increased highway capacity has shown to have resulted in readjustments of settlement patterns and an increased dependence on motor vehicles (9). People want access to timely, convenient, comfortable, and dependable mobility at an affordable price.

Transport plans should keep that in consideration and also should emphasize the movement of people not vehicles. This is the only way to achieve both satisfaction and increased quality of life with the least environmental and economic damage. DELHI’S TRANSPORTATION SYSTEM CHARACTERISTICS Compared with other big cities in the world, Delhi has less automobile usage, no subway or light rail passenger transport, and much more bus passenger transport and non-motorized vehicle usage (mainly walking and bicycling). Turnover period of vehicles in Delhi is about 20 years compared to 6-8 years in developed countries and in Delhi vehicles also lag behind European standards (Delhi just introduced Euro 2 norms in April 2000 for all new cars and Euro 1 for all heavy duty vehicles). Although there is a large rail network of 120km in Delhi, almost all passenger transport demand is met by road. Delhi has two ring roads and one ring railroad. Five railroads and nine roads, of which five are national highways, intersect in Delhi leading to large amounts of congestion in the city. There is no traffic segregation and lane discipline, and all motor vehicles as well as bicycles, tricycles, handcarts, bullock carts, animals, and pedestrians share the same road space. All this chaos results in about 10,000 accidents per year which causes about 2,000 deaths and 10,000 injuries. The public transport system is inadequate with only buses and poorly planned routes. There is yet no subway or light rail transport system (LRTS).

Increasing incomes and economic activities together with the inefficient public transport system has led to an increase in cars and two wheelers. The older and poorly maintained vehicle stock has contributed to the air pollution problem in Delhi. In 1995, Delhi was named to be one of the top ten most polluted cities in the world and the fourth most polluted city in the world in terms of particulate matter (10). Particle levels in Delhi consistently remain 3 to 5 times the national standards. Maximum levels of PM10 in a residential area in Delhi (Ashok Vihar) have reached 10 times the standards in October 2000 (11). Particulate pollution was reported to kill 1 person per hour in 1995 (12). The annual average ambient total suspended particulates concentration was around 400mg/m3 in Delhi in 2000. On the other hand, SO2 and NOx values tend to stay below the ambient standards and the 2000 annual average ambient concentrations of SO2 and NOx were 18mg/m3 and 40mg/m3 respectively. Also, about 14% of CO2 emissions come from the transportation sector in India with an increasing trend (13). An average car in India weighs about 800kg and emits 5 times its weight of CO2 in one year. The rapidly growing, yet inefficient and inadequate, transportation sector in urban cities of India could have large impacts on greenhouse gases emissions in the future. growing transport sector, many actions has already been taken to curb air pollution from motor vehicles and develop a sustainable transportation sector.

Leaded gasoline was phased out in September 1998 and catalysts were mandated on all new cars in October 1998. Delhi has introduced Euro II standards for all new cars in April 2000 and Euro I for all new light duty and heavy duty vehicles. Sulfur content of diesel and gasoline were reduced to 0.05% by weight in April 2000. Tighter motorcycle standards with mandatory use of catalysts were introduced in 2000. New retirement ages for vehicles were set up by successive rulings of the Supreme Court – after year 2000 the retirement age for cars was 25 years, for two wheelers 15 years, for autorickshaws 10 years, for taxis 10 years, for buses 8 years, and for trucks 12 years. The Delhi government banned the registration of diesel taxis in the capital starting January 2000 to control toxic particulate pollution in the capital. The use of alternative fuels and especially CNG buses are being pushed. The entire city buses (Delhi Transport Corporation (DTC) and Private) were to be steadily converted to CNG by September 30, 2001, but the deadline has been extended once more to March 31, 2002. The results of the implementation of such decisions are rather uncertain. Delhi Metro Rail Corporation is working on a large project for the implementation of Delhi’s mass rapid transport system (MRTS) which in its first phase plans to build 11km of subway and 41km of surface and elevated rail by 2005 in order to reduce congestion, air pollution, and accidents and save fuel and space (14).

The full system is planned to be finished by 2021 with 34.5km of subway, 35.5km elevated and 111km surface rail, and 17.5km of dedicated busway with a total system length of 198.5km. On the traffic demand management side, the Supreme Court has limited the monthly number of car registration to 1500 (previously 4000 vehicles per month were being sold). Finally, goods vehicles are restricted during the day within the city limits (December 1997). Delhi, which has experienced a massive growth in small-scale industries in the last 15 years, has been directed by the Supreme Court to relocate its 114 highly polluting stone crushers outside the city boundaries (15). Though how effectively this policy has been implemented is questionable. There is also a huge need for institutional and regulatory reform in Delhi. Multiple institutions are responsible for urban transport planning in Delhi. It is not clear which organization is responsible for doing what and many approvals need to be taken to be able to run and implement a project. There is a lack of coordination and poor enforcement. It would be better to have one overseeing body responsible for organizing and coordinating these many institutions to run more effectively and efficiently. Some of these organizations are private organizations and they do not share their data. There is a small amount of publicly available data with very little explanation about how they have been gathered or calculated, therefore with questionable credibility.

All these make models which are very data intensive, such as the ones being implemented here, easy to develop, but hard to calibrate. The following discussion is based upon the results of model runs using the best available data set. METHODOLOGY AND RESULTS Simulation versus Optimization Usually planners make simulations of one or more options to evaluate their cost effectiveness and to make comparisons. Using optimization requires less of the repetitive work involved in running many simulations, and it is an integrated way of looking at an extensive list of control options. The motor vehicle fleet in Delhi is represented in our simulation model by 6 different types: cars/jeeps/station wagons (categorized as cars), two wheelers, three wheelers (autorickshaws), taxis, buses, and trucks. Other modes of transport include bicycles, tricycles, light rail and subway. Walking is not entered as a transport choice in the models mentioned in this paper but calculations for this mode are made outside the model to check that this demand will be met. Walking trips made up 32% of the total trips in 1994 in Delhi (16). This accounted for about 7 million trips per day and totaled approximately 4.4 billion-passenger km (bpkm) (about 5% of the total PKM traveled in 1994). As motorization continued over the years in Delhi, walking trips were somewhat reduced. By 2000, roughly 4.4 million people out of 13.8 million people met their travel needs by walking; about 2.7 bpkm which was a little over 3% of total PKM traveled.

A spreadsheet simulation model, which is a vehicular air pollution information system for Delhi (VAPIS – 17, 18), using current growth rates of vehicles, retirement age prerequisites, strict emissions standards, fuel efficiency and fuel quality requirements, projects the number of vehicles, average vehicle fuel efficiencies (km/lt), average vehicle emission factors (g/km), age distribution of vehicles in each year, vehicle kilometers traveled by each mode in each year, fuel consumption, and emissions of pollutants (CO, NOx, HC, Pb, TSP, PM10, SO2, CO2). In addition to Delhi being under Euro II standards for all new cars (2000), the model assumes that Euro III and Euro IV standards will be enforced for all new vehicles by 2005 and 2015 respectively. The corresponding fuel qualities for sulfur content of gasoline and diesel are also required to comply with the Euro norms accordingly. Essential technological improvements in vehicle engine designs and fuel qualities are assumed to be accomplished to meet the mandatory emissions standards and fuel efficiencies. The aim is to investigate technology advancement’s impact (through emissions standards, fuel efficiency, and fuel quality requirements) on air pollution from mobile sources.

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Managing Air Pollution With Urban Transportation. (2019, May 30). Retrieved from