This study quantifies the gross carbon emissions from the construction and operations of ADB-funded transport projects approved between 2000 and 2009. It also identifies carbon intensity indicators linked to outputs, mobility, and investment, which can be used to track future performance. The main findings of the study were: (1) Expressway projects were found to increase CO2 emissions over their 20-year lifetime compared with business as usual because of effects on induced travel that overwhelm the short term benefits of curbing low-efficiency congested traffic. (2) Rural road and road rehabilitation projects were found to have a neutral or slightly reducing effect on CO2 emissions compared with business as usual. These improved the efficiency of traffic flow and reduced low-speed high carbon intensity travel. (3) Public transport investments and railway improvements, while generating new CO2, more than offset those emissions when they divert passenger and freight movements from higher carbon modes and improve the efficiency of traffic flows. (4) Investments that reduce CO2 tend to reduce air pollution and public health problems linked to transportation, while investments that boost CO2 tend to also boost air pollution and public health problems. Integrated transport investments that focus on both demand- and supply-side strategies, including operations and demand management, yield greater co-benefits for mobility, CO2, and pollution.