Data Methodology

Currency and conversion

All financial amounts are reported in Australian dollars unless otherwise stated. Figures in USD may have been converted to AUD using the exchange rate at 30 June 2017 (1 AUD: 0.7692 USD).

GHG emissions

Transurban uses The Greenhouse Gas Protocol: A Corporate Accounting and Reporting Standard (Revised Edition) to draw boundaries around emission sources when quantifying our Scope 1, Scope 2 and Scope 3 GHG emissions. Emission factors and calculation methodologies outlined in the Australian Government Department of Climate Change - National Greenhouse Accounts (NGA) Factors August 2016 are then applied to each data source.

The Environmental Protection Agency’s eGRID2014 v2 (released February 2017) is used to calculate Scope 2 and 3 GHG emissions from electricity in the USA.

Transurban applies the GHG Protocol’s air travel method and emission factors to individual flight details to generate our Scope 3 emissions associated with corporate air travel.

Australian Government NGA Factors August 2016 have been used to calculate Transurban’s Scope 3 emissions from waste, fuel use (for incident response and operations and maintenance vehicles), fuel refining and transport and electricity transmission and distribution losses.

Customer travel

GHG emissions from customer vehicles on our assets were calculated based on total distances travelled, vehicle type and speed.

Transurban’s traffic and tolling systems record information such as vehicle class and entry and exit points of vehicles. Supplementary information on some assets includes vehicle origin-destination studies, independent travel time studies, and assumptions based on the physical dimensions of assets. These data are used to calculate the total Vehicle Kilometres Travelled (VKT) on each asset for the year.

Transurban calculates resulting emissions using vehicle GHG emission factors that are sensitive to vehicle type, fuel and travel speed, sourced from the University of South Australia. Vehicle type is from Transurban tolling data. Travel speeds are based on GPS data from external provider TomTom to determine average travel speeds on Transurban assets. Fuel type is estimated based on the Australian Bureau of Statistics (ABS) Motor Vehicle Census 2017.