The transportation of dangerous substances by road increases from year to year, which means that the probability of an accident is also increased. Smaller accidents with various dangerous substances often happen. More rarely, major accidents occur where a larger amount of hazardous material spreads, fires or explosions occur, resulting in more widespread consequences. In this master's thesis, I modeled an accident involving a tanker dominated by petroleum products using the computer program ALOHA. I have assumed an accident in the parking lot of the border food Obrežje, where on average two accidents occur per year with the course of dangerous substances. In the theoretical part of the master's thesis, I researched the legislation in the field of transportation of dangerous substances, defined what such a dangerous substance and how to distinguish them, and reviewed the literature on the use and operation of the program ALOHA. In the experimental part, I investigated the physical and chemical properties of gasoline and diesel fuel and modelled the fuel for both types of fuels. I was also interested in how they affect the weather conditions in most of the area at risk. The program ALOHA as a result of modelling the given areas that poses a threat to human population. Based on a comparison of the results between gasoline and diesel, I concluded that gasoline has a higher risk of heat radiation in winter. Such a result can be attributed to several fast speeds in the winter season due to the wind tipping the flames in the wind direction. Next, I checked how the different diameter of the orifice through which the fuel flows affects the results. I modelled the heat radiation when a gasoline leaks from a tank forming a burning puddle, and how a toxic vapour cloud would move when only fuel leaks and vaporizes. More than an opening from leaking fuel, heating is also a vulnerable area in this background. I also modelled a BLEVE type explosion in the last part of my thesis.