Samenvatting
A typical traffic stream is composed of a wide assortment of vehicles ranging from motorcycles to tractor trucks with multiple trailers. This paper focuses on the heavy segment of the traffic stream beginning at about 4000 lb mass and includes pickups-vans, school buses, intercity buses and tractor-trailers; this segment will, be denoted as "trucks and buses". One important issue is the possible effects that the increased presence of trucks and buses will have on highway and roadside safety.