Synthetic population

Synthetic population The synthetic population is created by isolating the trip-set individuals and matching to them the individuals surveyed for physical activity. They are matched based on age and gender. For Accra, the age groups are different: the PA people are grouped into 15--55 and 56--69 and matched to the trip set ages grouped as 15--49 and 50--69. These random allocations are not captured anywhere in the VOI analysis.

Synthetic trips get_synthetic_from_trips takes the loaded trip set and forms from it the synthetic trip set. We add truck and bus driver trips (add_ghost_trips), if the input dictates that they should be added. We create two male truck drivers and two male bus drivers who each take one trip. (N.B. the bus drivers' mode is ''bus_driver'' to distinguish it from the mode ''bus'', which is assumed to be taken as a passenger.) Again, the ages are uniformly sampled from the lowest and highest ages of our existing population. The total duration is calculated as before, using the ''TRUCK_TO_CAR_RATIO'' (0.21) and ''BUS_TO_PASSENGER_RATIO'' (0.022, CIRT (2011), State Transport Undertakings, Profile & Performance 2008-09, Central Institute of Road Transport, Pune, India) respectively, and is split as before evenly between the drivers.

The bus and truck drivers do not get a person ID and so are not counted in the synthetic population. Therefore, they contribute to other people's exposure to injury risk and pollution, but they do not contribute to the health burden via the pollution or PA pathways. As they have ages and genders, they do contribute to the at-risk-of-injury road-user population.