The Impact of Active Transportation Infrastructure on Travel-based Greenhouse Gas Emissions and Energy : A Longitudinal Before-After Study of Vancouver’s Comox-Helmcken Greenway
Creators: name: Ngo, Victor D.
Publisher: name: The University of British Columbia
Year: 2017

description: Objectives: This study investigated the transportation greenhouse gas (GHG) emissions, motorized energy consumption, and physical energy expenditure impacts of an urban greenway for residents in a walkable, mixed-use urban neighbourhood. Researchers have documented positive associations between the built environment and travel patterns, including environmental and health outcomes such as reductions in vehicle kilometres travelled (VKT) and higher levels of physical activity (PA). However, there is limited evidence to date of a causal impact of how changes in community design and transportation infrastructure affect emissions and energy, as the majority of existing studies are cross-sectional. For this reason, longitudinal natural experiments are currently a priority among researchers to establish causality between the built environment and travel-related outcomes. Methods: This study uses a Canadian case study of the Comox-Helmcken Greenway, a two-kilometre pedestrian and bicycle pathway in the West End neighbourhood of downtown Vancouver, British Columbia. It represents the first known longitudinal before-after controlled study of an urban greenway in Canada, conducted over a period of four years from 2012 to 2015. The sample consisted of 207 participants divided into two groups: 135 participants living within one-block of the Greenway (treatment group), and 72 participants living at least half a kilometre away from the Greenway (control group). A two-day personal Trip Diary Survey was administered to participants in order to track their travel patterns. Using data from the Trip Diary Survey, two models were used to estimate average daily motorized GHG emissions, motorized energy consumption, and physical energy expenditure. Results: Positive benefits were found for motorized GHG emissions, with a statistically significant reduction of −22.9% for average daily motorized GHG emissions (before: 1.1 kg CO2e; after: 0.9 kg CO2e). Likewise, average daily motorized energy consumption saw a statistically significant reduction of −23.7% (before: 16.0 MJ; after: 12.2 MJ). Average daily physical energy expenditure equivalent by motorized travel saw a statistically significant reduction of −22.9% (before: 14,129.6 kcal; after: 10,891.1 kcal). However, energy expenditure by active travel saw a non-significant decrease of −2.0% (before: 88.9 kcal; after: 87.1 kcal). Conclusion: The study’s findings lend evidence to support the claim that active transportation improvement projects may have a beneficial causal impact on improved environmental outcomes. The Comox-Helmcken Greenway yielded significant reductions in transportation GHG emissions and energy consumption for residents living within one-block of the Greenway, highlighting the important contributions active transportation infrastructure can make for climate change policy and emission reductions. However, there were mixed results for changes in health energy outcomes; more research with improved methods is needed to better understand the impact of greenways on physical energy expenditure.