SUMMARY
A three-level model for estimating greenhouse gas (GHG) emissions by mobile and stationary road transport facilities of a state or region, proposed in this article, takes account into GHG emissions from a vehicle fleet (mobile objects) and road transport infrastructure (network of car services, road network of various categories).Additionally, it has been developed the intellectual system which evaluates the reliability of the array of initial data, by increasing the range and adjusting (if necessary) the values of individual indicators, as the result we achieving the convergence of the calculating GHG emissions from motor vehicles according to the models of all three levels of assessment. This ensures verification of the obtained gross GHG emissions.Evaluation of greenhouse gas emissions using three-level model was carried out for St. Petersburg and the Leningrad Region (Russian Federation), they shown the possibility of reducing by 2030 by 3.2 ... 12.4% of gross GHG emissions by motor transport of the Russian Federation in comparison with 2015. For St. Petersburg and the Leningrad Region, both the reduction of gross GHG emissions by road transport (12.7% innovative scenario) and their growth (4.8% inertial scenario) are expected during the forecast period. At the same time, both for the St. Petersburg and the Leningrad Region and for the state as a whole, a significant reduction in gross GHG emissions by road transport is expected in the period after 2025 due to the intensive replacement of cars on oil fuel by electric vehicles and hybrids, changes in the transport behavior of the population, the development of public passenger transport and cycling, the introduction of autonomous vehicles, etc.