Quantifying Benefit-Cost Ratios for a Low Emission Zone against Heavy Duty Diesel Vehicles in the Bangkok Metropolitan Region

Abstract

Unhealthy levels of fine particulate matter (PM2.5) contribute to significant human disease burden in the Bangkok Metropolitan Region (BMR). A Low Emission Zone (LEZ) targeting old heavy-duty vehicles (HDVs) can supplement current government policies and marginally reduce the concentration of ambient PM2.5. Health benefits and vehicle upgrade costs were quantified to calculate benefit-cost ratios (BCR) as a mean to assess the feasibility of a LEZ. BCRs were calculated for a prospective LEZ that prohibits Pre-EURO/EURO I HDVs from entering the BMR, with two outcome scenarios: replacing the targeted HDVs with EURO III HDVs and replacing the targeted HDVs with EURO IV HDVs. The analysis period was 2020 – 2035, with the hypothetical LEZ beginning in 2022.

The health benefits of the EURO III outcome scenario were calculated to be $270.15 million against a technology upgrade cost of $29.45 million, for a BCR of 9.17. The health benefits of the EURO IV outcome scenario were calculated to be $308.98 million against a technology upgrade cost of $138.03 million, for a BCR of 2.24. Due to substantially lower technology upgrade costs, the EURO III scenario outperformed the EURO IV scenario. Both outcome scenarios resulted in a BCR greater than one, matching the hypothesis. However, the best outcome scenario was the EURO III scenario, instead of the hypothesized EURO IV scenario, with a BCR value significantly higher than the predicted 2-3 estimation. The relatively high BCR values suggested that a LEZ is a policy option worth immediate consideration, alongside with the current HDV EURO III exhaust standard. It is not necessary for the government to improve contemporary standards to EURO IV before a LEZ implementation. Furthermore, the methodology in this study presented a more streamlined process to calculate BCRs by only quantifying the most relevant benefit and cost factors unbiasedly. It is hoped that the methodology is standardized so that other future LEZ feasibilities studies could have a base common indicator BCR that can be directly compared with each other.