This research deals with equivalent dose rate (EDR) in the ground level air caused by gamma radiation. Weighting factor for gamma radiation is equal one, so EDR in the ground air is identical absorbed ionic radiation dose. Highways A6 Kaunas-Zarasai and A11 Panevėžys-Šiauliai-Palanga were investigated. In this research the main parameters determining the level of equivalent dose rate in the ground air by the Lithuanian highways have been defined and analyzed. The objective of this research is to measure EDR in the ground air by the Lithuanian highways and compare to adequate average regional and with reference to modulation values evaluate variation reasons. In the expeditions EDR in the ground air was measured in winter and in summer. Samples of soil and asphalt were examined with gamma spectrometer and analyze presented. There was determined the dependence of EDR in the ground air from soil composition, floral or snow cover and distance to the asphalt cover. Cosmic radiation impact on EDR formation is equal to all locations. Natural origin radionuclides in soil gamma radiation have the main influence to EDR formation in the ground air. Modeling program VISIPLAN was used to define impact of radionuclides radiation in asphalt cover to EDR formation in the roadside zone. Modeling program InterRAS was used to define EDR in the ground air formation from gamma radiation of radionuclide in soil.