Reducing traffic emissions is key in transport planning and infrastructure management in order to achieve a sustainable transport system. This paper contributes to this topic in two ways. The first step describes a comprehensive methodology for identifying hot spots road segments and corridors with problems of GHG emissions to enable low-carbon actions. The Highway Energy Assessment (HERA) methodology is applied to the national road network of Spain in order to estimate interurban traffic emissions and calculate the emissions index to assess strategies. The results are shown graphically on a GIS, allowing to identify seven corridors with emissions problems comprising 25% of the network and being responsible for 51% of the total GHG emissions in 2012. Inefficient corridors were those with high rates of heavy vehicles, high speeds and steep gradients. The second step consists of the application of a set of strategies to reduce their emissions and their comparison to the reference scenario. The Mediterranean corridor—the most inefficient corridor—was selected to apply a set of abatement strategies. The most effective strategy was speed enforcement for light vehicles. A speed reduction of 10 km/h could produce a 3.5% savings in emissions compared to the reference scenarios, and decrease emissions intensity from 254 gCO2eq/veh-km to 246 gCO2eq/veh-km.