GIS road digitizing

Objective: digitize roads using high resolution satellite imagery for area in Tanzania. Where: The area is defined by the attached area_of_interest.shp. What: three classes of roads primary, secondary, and tertiary. Please use the attached [login to view URL] as a guide. We do not, however, need footpaths. Just roads that could be accessed by vehicle/car. Method: suggest using google earth imagery as a backdrop either in google earth or using QGIS plugin. Must use a contemporary high resolution image backdrop.