The issue of shifting loads from road to rail is always vivid when it comes to reducing CO2 emissions from transport. Practically not every load transported by road vehicles over a long distance can be transferred to rail. Additionally, the potential of the railway lines is limited, which means that the network is not able to accept huge amounts of loads from road transport. In the article, attention was paid to the typology of cargo susceptible to changing the means of transport. The article discusses the factors influencing the real possibility of CO2 reduction by changing the mode of transport. The analysis and calculation example of the selected region in Poland is presented.