Road traffic emissions have rapidly increased due to urbanization and motorization. Accurate estimation of these emissions is imperative for effective policymaking. This paper presents a model prepared using Geographic Information Systems (GIS) for spatially disaggregating road traffic emissions in megacity of Delhi for the year 2018. The study integrates the emission estimation based on the approach by COPERT methodology and the gridding of emissions at a high resolution based on the road density of the area. GIS techniques are employed to analyse and prepare the datasets for allocating emissions to geographical areas. The emissions are allocated based on gridded road density. The estimated total emission of heavy metals from vehicular sources is 695.202 Mg/year. Copper (71%) and lead (73%) were the significant contributors to the brake wear and tyre wear emissions, respectively. The geographical region with a dense road network reflects high congestion and is considered as a major emanating hot spot. The exhaust emission inventory is accompanied by uncertainties due to the considerable variation in the emission factors. The research findings highlight the importance of spatial distribution of emissions essential for developing mitigation plans to reduce emissions from motor vehicles.