Does cycling to work always reduces carbon emissions? What impact on carbon emissions a cycler will have by blocking a traffic lane? Is it a good idea to have dedicated bike lanes?

Do bicycles actually reduce carbon emissions in a city of your choice?

Does cycling to work always reduces carbon emissions? What impact on carbon emissions a cycler will have by blocking a traffic lane? Is it a good idea to have dedicated bike lanes? This project looks into the full impact of cycling on the traffic CO2 emissions. The project will take any city as a case study.