Pragmatic approach:
1. Segment into types of vehicles
2. Estimate pollution intensity per vehicle type (e.g., if it takes 30 seconds to pass the roundabout on average, what is the pollution per 30 secons?)
3. Estimate number of vehicels for each type per time of the day (rush hours vs non-rush hours)
4. Multiply sum of 3. with 2. for each type and sum up
Cheers, Sidi