The climate change is a major global problem, due to releasing the greenhouse gases (GHG) to the atmosphere at an alarming rate. The main constituent of GHGs is carbon dioxide (CO2) and impact of all other gases is measured in relation to CO2. Hence, GHG emissions are referred to as carbon dioxide equivalent or carbon emissions or Carbon Foot Print (CFP). Transport is a major human activity which contributes to the emission of GHGs. In Sri Lanka there are no previous studies done to evaluate the carbon emissions from any road project. Unless mitigation measures are implemented, Sri Lanka's GHG emissions will reach dangerous level. Therefore this study was done to estimate the Carbon Foot Print and analyse the emissions variation on Southern expressway from Colombo to Galle due to vehicle movement under the operational stage. The results can be used by policy makers for development planning of roads and associated infrastructure as well as to develop strategies for mitigation of carbon emissions through the changes of road network.