Before and After BRT: Using Remote Sensing to Measure Impacts on Urban Growth Patterns in Quito (Ecuador) and Cali (Colombia)
Nominated for The Planning for Sustainable Land Use and Transport Award
LUIS EDUARDO TAFUR H, AECOM
I used satellite data to measure urban growth before and after the introduction of BRT in 2 cities considering 3 scales: urban, treatment and control. Growth rates increased in the urban scale but results varied in the treatment and control scales
The relation between urban form and transportation systems has been studied for several decades. However, remote sensing has been less used to specifically asses possible impacts of public transportation systems on urban growth patterns. Bus Rapid Transit systems (BRT) have exponentially increased popularity across the globe, particularly in the developing world, in less just two decades. Latin America is currently the region with the largest portion of BRTs in the world, but little is known about the impacts of these systems on urban growth patterns. Although several studies have assessed the possible impacts on property value, land uses, and the built environment, remote sensing has not been used to particularly examine the intersection between BRT systems and their potential impacts on urban land growth.
This study uses Landsat data over 4 points in time for two Latin American cities: Quito (Ecuador)), and Cali (Colombia). Landsat data form years 1986, 1991, 1996, and 2001 was used for Quito, and 1999, 2003, 2011, and 2015 for Cali.
The objective of this methodology is to quantify the growth rate of urban built-up area before and after BRT implementation in both cities. The design of the research is a before-and-after analysis with controls. In order to measure the change of developed (or built-up) urban areas, I use Landsat satellite images to perform a supervised land cover classification with ArcGIS and quantify the amount of developed land in four different points of time for each city. Then, the built-up land growth rate is calculated before and after the BRT implementation. Such analysis is performed in several scales (Urban area scale, BRT scale, and Control Scale). Particular focus is made on BRT scales (treatment area) and control scale (Control area) in order to evaluate possible BRT impact in comparison with city areas outside of BRT influence.
The greater urban areas of both cities have considerably increased their urban growth rates in the time period after the BRT implementation. This increase is higher for Cali which has almost doubled its urban growth rate (from 8% to 15%) while Quito, has increased it from 20% to 27%. However, when focusing on the BRT influence area, and comparing with a control zone, BRT buffers also showed increased urban growth rates after the BRT implementation with some particularities. While Quito’s BRT buffer urban growth rate changed from 2.5% to 3.7%, the control zone only changed from 5.9% to 6.2%. Cali did not show a considerable difference between the BRT zone (1.8% to 3.0%) and the control zone (1.8% to 2.7%) but still reported a slight increase in urban land growth rates after BRT.
While the rapid expansion and declining tendencies of Latin American cities was confirmed in a overall city scale, in the BRT influence scale, results show a clear relation between the BRT and increased urban growth rates in Quito, but less so in Cali. Potential planning, policy, and value capture applications can be derived from this study and despite its limitations, it is considered as a useful tool for further standardized analysis of BRT relations with urban growth across different cities in the world.
Association for European Transport