Evaluating Nocturnal Buses as an Efficient Policy to Combat Drunk Driving and Reduce CO2 Emissions in Large Metropolitan Areas: The Case of Guadalajara, Mexico

Abstract

Road traffic incidents associated with alcohol consumption in Mexico are a public health risk that affect people from 20-39 years of age (Comisión Nacional contra las Addiciones, 2022). According to the World Health Organization (WHO), binge drinking, or heavy drinking episodes, increase from age 15-19 and peaks at 20-24 years old (2018a). Among the policies to tackle drunk driving, strong evidence suggests that sobriety checkpoints are effective policies to reduce drinking and driving (Cheng & Pien, 2018). However, further reduction of drinking and driving cases requires the availability of alternative transportation methods, which can be achieved by extending the schedule of public transportation at night. Channeling these at-risk drivers to public transportation might also help reduce CO2 emissions. This thesis is divided in two parts. First, I sought to measure the effectiveness of the sobriety checkpoint program implemented in Guadalajara’s metropolitan area since 2013. To provide additional support in favor of the extension of the bus schedule at night as a measure to reduce road traffic incidents, the second part of the thesis focused on calculating the CO2 emission reduction from this measure in five bus routes of Guadalajara as an alternative method of transportation to cars. My research was guided by the following questions: has the sobriety checkpoint program had an impact in the number of road traffic incidents in Guadalajara’s metropolitan area? How many CO2 emissions could be avoided by transporting a set number of people in buses instead of cars at night? The hypothesis tested was that there was a statistically significant decline in the trend of road traffic incidents in Guadalajara’s metropolitan area before and after the implementation of the sobriety checkpoint program. The second hypothesis was that 30% of CO2 emissions could be avoided by taking round trips by electric or diesel buses at 50% occupancy compared to round trips by gasoline or electric cars at full occupancy, or a mix of buses and cars. The research began with an interrupted-time series analysis of the sobriety checkpoint program and found that there’s a statistically significant decreasing trend in the number of road traffic incidents since the implementation of the program. A Poisson regression analysis of the DUI incidence of the sobriety checkpoint program found a statistically significant decreasing trend in positive test from 2013-2019. Additionally, I mapped five routes in Guadalajara’s metropolitan area to estimate the CO2 emission per km travelled by two gasoline cars, two electric ones, one diesel bus and one E-bus. I examined round trips by each car and bus model, and round trips with a combination of a diesel or E-bus and a transportation network company (TNC). The E-bus had the biggest advantage compared to gasoline cars and the diesel bus, but having EV traveling at full capacity emitted less CO2 than the E-bus at 50% capacity. On the other hand, the diesel bus at 50% occupancy did not avoid ≥30% of CO2 emissions through the five routes mapped, refuting that hypothesis. However, at full occupancy of the buses, or reduced occupancy of the gasoline cars, significant reductions in CO2 emissions can be achieved. A 20-year sensitivity analysis of the five routes mapped found that substituting TNC trips for E-bus round trips at 50% occupancy, two nights per week, can avoid a minimum of 313,282 kg CO2 emissions.