Emission Testing Services

MEASUREMENT OF TRANSIT BUS EMISSIONS IN THE INSURGENTES CORRIDOR OF MEXICO CITY

Client: Secretaría del Medio Ambiente, Gobierno del Distrito Federal, Mexico

EF&EE was contracted by the Secretaría del Medio Ambiente (SMA) of the Government of Mexico City to carry out emissions measurements on public transport buses operating in the Insurgentes corridor, which forms the route of the new "Metrobus" segregated-lane bus rapid transit (BRT) line. The purposes of EF&EE's work were: (1) to measure emissions from a sample of the buses and microbuses that formerly operated on Avenida Insurgentes; (2) to measure emissions from the new Metrobuses; and (3) to measure emissions from various advanced and "clean" technology buses being considered for future adoption. This effort was conducted as part of the "Project for Introduction of Climate Friendly Measures in Transport", funded by the Global Environment Fund, and administered by the SMA and the World Bank.

Three rounds of testing were performed from November, 2004 to October, 2005. The buses tested included twelve conventional diesels, two diesel-electric hybrids, and three using compressed natural gas in lean-burn engines. The four microbuses tested included one using gasoline in a stoichiometric engine, one retrofitted to use LPG, one retrofitted to use CNG, and a bi-fuel CNG/gasoline vehicle. Two diesels and one hybrid were fitted with diesel particulate filters (DPFs). All of the CNG buses and microbuses were equipped with catalytic converters.

On-board emission tests were performed using the SMA's RAVEM system, which was purchased from EF&EE for this project. The test route comprised a 21.4 km round-trip along Avenida Insurgentes. Tests were done in driving conditions corresponding to normal daytime traffic and to operation along a segregated bus lane. Particulate matter (PM), oxides of nitrogen (NOx), carbon monoxide (CO), carbon dioxide (CO2), and carbonyls such as formaldehyde, acetaldehyde, and acrolein were measured successfully. Individual VOC such as methane, ethane, ethylene, etc. were also measured successfully for some tests. The results showed a wide range of emissions, even from buses nominally certified to the same standards.