Townsville Vehicle Emissions

Townsville's air quality is influenced by many factors including vehicle pollution.

But how much pollution do Townsville's cars produce?

Using a variety of data: (Main Roads, EPA and Bureau of Statistics) it has been possible to make an estimation of vehicle pollution along a sample stretch of road (see picture below left).

This information provides a snapshop of vehicle pollution along a commonly traveled stretch of road. The sample road runs form the corner of Boundary Street and Saunders Street, Railway Estate, through the CBD to Hugh Street adjacent to the Lakes. Over 52.5 million vehicle/kilometers (VKT) were travelled on it in 2001 .

Five pollutants have been estimated:

• nitrogen oxide (NOx)
• carbon monoxide (CO)
• total hydrocarbon (THc)
• particulate matter (PM10)
• sulphur dioxide (SO2)
• carbon dioxide (CO2)

Information about air pollutants from the Australian Academy of Science.

However, in order to generate these figures, a number of assumptions have been made about the vehicles that travel along the sample road. These are detailed below. For example, rather than account for every type of vehicle, the estimation assumed that only petrol driven sedans used the road and that the vehicles traveled a constant speed (50km/h).

Commentary on the estimation have been supplied by the EPA. This commentary puts the estimation into context by considering a number of factors that were not accounted for in the estimation technique. For example the varying speeds of vehicles on the sample road and the different types of vehicles.

For example:

• Carbon dioxide is a greenhouse gas and transport is the fastest growing sector in national greenhouse emissions, with an anticipated increase in emissions of 38% between 1990 and 2010 (see Australian Greenhouse Office - Transport). On the sample road, it is estimated that about 12,594 tons of carbon dioxide were emitted by traffic. However, it is likely that the greenhouse emissions on the sample road are twice as big (24,000 tons) given the repetitive stop-starts anticipated on a stretch of road with 14 sets of traffic lights.

• Vehicle emissions also contain PM 10 particulates tiny particles less one fifth the width of a human hair. Two particulate measuring stations in Townsville (Garbutt and South Townsville) continually show Townsville's air quality to be within accepted limits (click here to see data). The estimation shows vehicles to emit about 0.45 tons particulates per year. However, the EPA commentary suggests that particulate emissions could be as much as 100 times higher (~45 tons) due to the estimation excluding the emissions from trucks and light duty diesels.

• Total hydrocarbon emissions may be 2-4 times higher than the 16.9 tons in the estimate (34-68 tons). This is would account for higher ambient temperatures in Townsville and associated fuel evaporation rates.

• Nitrgen oxide and carbon monoxide emissions are likely to be underestimated by a factor of 2-3 due to the omission of stop-starts and heavy duty vehicles from the estimation. This would raise Nitrogen oxide emissions from ~58 tons per year to between 116 and 174 tons, and carbon monoxide emissions from 291 tons to between 582 to 873 tons.

This estimation, demonstrates that vehicle pollution is a measurable phenomena, even with limited information. Presentation of this data enables the reader to get a sense of vehicle emissions for a small stretch of road. In light of this, the reader is invited to consider what the total emissions from all vehicles in Townsville might be. Then consider what these emissions will be in 2050 with a projected projected population of 320,000.

Data used in the estimation.

The estimation was produced using a variety of data including:

AADT and VKT data from Queensland Department of Main Roads (see below for definition of terms).

Vehicle Emissions data from the Environmental Protection Agency.

Traffic Census data from Queensland Department of Main Roads.

Vehicle census data from the Australian Bureau of Statistics.

The estimation above is not a thorough analysis of vehicle emissions in Townsville. Such a calculation would be possible but would require much information. However, even then it would require complex polynomial equations incorporating percentage of vehicle classes, vehicle ages, average speeds over varying stretches of the road, fuel types, and vehicle types and other parameters. Potentially a very expensive modeling exercise.

Instead, this data above represents the emissions associated with the class of vehicle most representative of the vehicles described in the AADT and Vehicle Census data, multiplied by the VKT figures. Necessarily, a number of assumptions were made to support this information. These are detailed below (see Assumptions and Rationale)

Main Roads AADT Data

Main Roads Northern (Townsville) District

AADT segments report for North Ward Road section 833

Hourly AADT Averages

Daily AADT Averages Forecast AADT Growth

VKT Data for North Ward Road section 833

• Average Speed
  Assumption: Speed Class 6: 51-60 kilometres per hour. Rationale: The speed limit across this stretch of road is 60kmh although average speed is likely to be lower due to traffic lights.

• Vehicle Type
  Assumption: Average Age of Vehicles of vehicles is 1988. Rationale: This figure was derived by averaging the age of all the cars referred to in the Traffic Census 2001. Vehicle age is an important considerations in emissions as is shown by this Federal Office of Road Safety Report Motor Vehicle Pollution in Australia (.pdf 72kb)

• Fuel Type
  Assumption: All the vehicles moving across the sample road are petrol driven vehicles. Rationale: The AADT data shows that ~97% of the vehicles on this stretch of road are classified as short vehicles. Short vehicles are typically petrol driven motor cars. Short (96.9%), Truck or bus (2.7%), Articulated (0.4%).

AADT is Annual Average Daily Traffic .

Vehicle Pollution Links

Commonwealth State of Environment Report on Urban Air pollution including references to vehicles

Transport/Air Quality Links provided by Environment Australia

National Phase out of leaded petrol

Queensland State of Environment Report - Key Findings -Atmosphere (111KB .pdf)

Report of the Biofuels Taskforce to the Prime Minister (1.8MB .pdf)

Queensland EPA Air Pollution Information