## 1 Introduction
This type of inventory in the transport sector focuses on ground transportation in cities, but it does not usually include intercity transportation (road transport). In-depth studies of emission inventories on roads have been identified specifically for freight transport. A study based on surveys applied to transport companies was carried out, where information was gathered about energy consumption, distance traveled, and vehicle performance by Heavy Goods Vehicle (HGV) weight class. The methods of calculation in the UK use four approaches (described in Section 2) to estimate CO\({}_{2}\) emissions from road freight transport. The conclusion of this study describes the need to reconcile differences in truck-km estimates based on surveys and roadside traffic counts depending on the scope of the analysis [16]. Another study evaluates the environmental impact of a major freight corridor in California, particularly associated with heavy-duty diesel trucks. The baseline was developed using a traffic microsimulation tool (TransModeler). In this study, vehicle emissions depend on vehicle type, model year, and fuel type. This methodology estimates instantaneous emissions and the fuel consumption rate for different vehicle types and estimates emissions under various traffic operational scenarios (such as congestion, traffic signals, and High-occupancy vehicle lanes). The results show that utility is applied to this process to evaluate scenarios; however, they exclude infrastructure characteristics [25]. The Commission for Environmental Cooperation developed a study to determine the actual impact of CO\({}_{2}\) emissions in the transport corridors of North America and its future impact [10]. The methodology developed a bottom-up approach; however, a few variables such as traffic flow, emission rates, corridor data, and truck data were considered in the analysis in order to establish comparability between the three countries of the region (Canada, Mexico, and the United States of America). The information used in this study also does not include detailed information about road characteristics to obtain a reliable measure of emissions to construct a baseline. To implement emission reduction strategies, it is necessary to have a reliable emission inventory that allows the establishment of a baseline in order to measure the impact of the action on the mitigation of climate change. In order to reduce GHG emissions in freight transportation, it requires using appropriate emission models and integrating data into the bottom-up methodology in the planning process, to develop a reliable emission inventory [26]. Rapid urbanization and economic growth in developing countries have spurred air pollution, especially in the road transport sector. The increasing demand for petroleum-based fuels and their combustion in internal combustion (IC) engines have adverse effects on air quality, human health, and global warming [27]. Addressing climate change in developing countries poses a fundamentally different challenge. Developing countries will continue to increase their emissions due to economic growth and a better quality of life [28]. Forecasts of emission in Mexico trends shown in Figure 1 show a significant growth in GHG emissions [29]. Appropriate strategies are required to reduce these future increases, such as the ones analyzed [30], where 21 GHG mitigation measures were applied to reduce transport sector GHG emissions in Mexico. This, therefore, results in the need to develop a methodology to estimate emissions in transport corridors in developing countries such as Mexico through a bottom-up approach. The aim of this study, on one hand, is to develop a methodology with a bottom-up approach, with as many variables of road transportation, and to obtain an emission inventory for measuring CO2 emissions of freight transport in road corridors for Mexico. Additionally, this study seeks to establish environmental indicators with the results applicable to CO2 in transport corridors.