Vehicle Type and Pollutant Emission

Vehicular emission has become a major source of pollution in many areas. Traffic pollution causes a significant increase in carbon monoxide (CO), carbon dioxide (CO2), volatile organic compounds (VOCs) or hydrocarbons (HCs), nitrogen oxides (NOx), and particulate matter (PM). Increasing the duration of road congestion rises emission pollution and degrade air quality.

Increase congestion on the urban roads and number of vehicles adds to the emission level and in turn increasing pollution level. In the present analysis, we have used COPERT model (Computation Of Pollutant Emission from Road Transport) to determine the contribution to emission by vehicle type (2W: Two Wheelers, HDV: Heavy Duty Vehicles, LDV: Light-Duty Vehicles, PC: Passenger Cars) in different running conditions.

The following analyses were done for CO (Carbon monoxide), the most affecting pollutant.


Two stroke Engine vs Four Stroke Engine Emission level

First, we look at the emission level difference between 2 Stroke engine vehicles and 4 stroke vehicles. Let us look at the plot of Emission in gram/vehicle/km for 2 stroke vs 4 stroke 2 wheelers, at several speeds.

At lower speed, vehicle emission is higher which is fact. 4 stroke engine emits 50% less pollutant which further decreases to 20% of 2 stroke engines. For both 2 stroke engine and 4 stroke engine, the emission is decreasing with an increase in speed in the given range, but the emissions are overall more in case of 2 stroke engine. In India, 78% of all registered vehicles are two-wheelers which are all two-stroke engines.


Comparison of emission by different vehicle type.

Using the COPERT model we calculate the emission level of different vehicle type at different speed. We plot emission at various speeds for selected vehicle types, hdv(slope 0, load 100%), ldv (diesel), pc (gasoline 4 stroke), 2W (gasoline 2 stroke).

Heavy duty vehicle and two-wheelers are most polluters. Given the fact that 78% of all registered vehicle in India are two-wheelers. Some of the areas they are the major source of pollutant emission.


Emission from Vehicle compliance with Euro -3 and Euro – 4

Next, we calculated the emission level by vehicles compliance with euro -3 and euro – 4 at various speed.

For Heavy Duty Vehicle (HDV), expected emission reduction is 50% by moving from euro-3 to Euro-4 standard. For light-duty vehicle (LDV) similar reduction is not so significant, but almost 70% reduction is expected in personal vehicle (PC) segment.

Conclusions – This analysis used a different vehicle type and its pollution impact. Congestion can increase the pollution level as high congestion level cause reduce traffic flow. All vehicle type emits 2X more pollutant at a lower speed than higher speed. Two wheelers are a major source of emission and some kind of regulation to will help urban pollution because of vehicle traffic. Euro – 4 compliant vehicle emits 50% less pollutant compare to euro-3 compliant vehicles. An initiative to reduce euro – 3 compliant vehicle and move all the vehicles to euro-4 complaints or higher will further help reduce air pollution in an urban area.

The above basic analyses of vehicle type and emission standard can give the idea and lay the foundation stone for building sophisticated pollution models for cities.