The resulting marginal external noise cost for the 2005 reference situation is given in
Table 13. As expected, the marginal external noise cost generated by a vehicle is much
higher in the off-peak period than in the peak period hours of the day. Indeed, an extra
vehicle on a quiet moment causes more disturbing noise than an extra vehicle on top of a
lot of congestion. By definition, the marginal external noise cost of heavy vehicles is 10
times higher than that of passenger cars.