Air pollution modelling for Chennai city using GIS as a tool Fleet characteristics An improved capability to identify the emission significant components of the operating fleet is important to emission rate accuracy. Spatially variant emission estimates are needed, requiring spatially resolved sub-fleet characterization. Therefore, there is a need for identifying procedures that can accurately predict spatially resolved vehicle characteristics for urban areas. Vehicle characteristics The first vehicle characteristic module has two major tasks: determine individual vehicle location parameters and emission-specific characteristics. Vehicle geocoding Address Geocoding is a process whereby standard address fields of road name, road type, and ZIP code are used to identify corresponding lines in a road database. Decoding Raw registration data can usually provide a few important vehicle characteristics (VIN, make, model, model year, and number of cylinders), but more information can be developed from the vehicle identification number (VIN). These files should represent a comprehensive description of the region’s fleet characteristics. These files can be further processed to develop the emission-rate specific fleet distributions. High emitting vehicles A high emitting vehicle is one that has malfunctioning or tampered with emission control systems causing higher than normal emissions. It is expected that a small percentage of high emitting vehicles account for a large percentage of total emissions. High emitter determination is an important model design parameter and therefore it is appropriate to characterize these vehicles differently. Technology grouping Once vehicles are identified as high or normal emitters, they are characterized into technology groups. Technology grouping is the process of combining vehicles according to the emission standards of the make. Vehicle activity The emission-important vehicle activity estimates provided by the regional travel models are: the number and location of peak hour (or daily) trip origins, road segment volumes, and road segment average speeds. Temporal travel behavior and modal (idle, cruise, acceleration, and deceleration) operations. This
The impacts of road grade on emissions are included in the model design. Road grade affects vehicle emissions by impacting the load on the engine. Gravity exerts a force on a vehicle that must be counteracted to maintain a constant speed. Road grade is not included in mandated emission models because tests on the actual effects have not been completed and because metropolitan areas do not maintain spatially defined road grade estimates. Including vehicle activity impacts resulting from road grade provides an important step in emission model development.  Conceptual design of the proposed research model |