In this study, Leq(5 s) and the maximum emission levels of
individual vehicles were measured in two sites. One was in a
two-way, four-lane, first-class highway with asphalt concrete
pavement and a greenbelt as the median strip in the rural area.
The other was in a suburb highway with four two-way lanes with
cement pavement and without median strip. The noise level metre
was placed at distances of 3.75 m perpendicular to the centreline
of the outside traffic lane and 7.5 m perpendicular to the centreline
of the inside traffic lane for the rural highway, and distances of
1.88 m to the outside lane and 5.63 m to the inside lane for the
suburb highway. Because the vehicles did not always run on the
centreline of the traffic lane, the real distance was estimated and