Frequently asked questions

What company conducted the travel time survey?

The survey was conducted by Austraffic, a national company with over 25 years experience in all aspects of traffic, public transport, parking and pedestrian surveying. Austraffic is the largest transport survey firm in Australia, and has undertaken numerous travel time surveys from the small to the very large.

How was the travel time survey conducted?

Each driver was required to complete an initial training run, whereby they drove the route prior to the survey date to gain familiarity and ensure they know the roads to travel. For each comparison the drivers were instructed to leave at exactly the same time undertaking the 'floating car' methodology, which requires drivers to travel with the general traffic conditions.

The exact same vehicles were used for all of the survey routes. This allowed for accurate comparison of fuel consumption using onboard vehicle computers.

Three survey runs were conducted for each comparison with the average result of the three runs reported for the purposes of this report.

When was the travel time survey commissioned?

Surveys were conducted during May 2010. No surveys were undertaken on days which were affected by public or school holidays. The weekend survey was conducted on a Saturday between 10am and 4pm.

How was the travel time survey recorded?

Drivers used custom built GPS units to record a second by second track file for each journey. After completion of the survey, the track file was reviewed graphically to ensure that the route had been surveyed correctly.

How were the greenhouse gas emissions calculated?

Greenhouse gas (GHG) emissions were calculated for each travel time survey using the measured unleaded fuel consumption and Australian Greenhouse Office emission factors.

The AGO Factors and Methods Workbook was published in December 2006 by the Department of Environment and Heritage Australian Greenhouse Office, and provides a single source of current greenhouse gas emissions factors for use by Australian organisations.

Section 1.2 of the AGO workbook contains the following formula to calculate greenhouse gas emission based on fuel consumption:

GHG emissions(t CO 2-e) = Q(kL) x EF

Where	Q	= the quantity of fuel (in thousand litres) consumed
	EF	= emission factor for fuel combusted
		= 2.4 (Automotive gasoline)