Urban Transportation and Logistics

163Road Safety

(large-sized car and three-axle truck) ratio reaches 40%—standard per-

centage in Japan. Now we also assume the distance among the vehicles

when they are in normal trafc and heavy trafc: 19.4 m for normal

trafc and 2.7 m for heavy trafc (those values are assumed using the

data of Japanese trafc).

On the basis of the values in Tables6.2–6.4, the number of vehicles

simultaneously on the bridge can be obtained by the following equation:

N

L

LL

i

i

Vj

Hj

j

N

1

v

∑

{}

()

=

γ

+γ

=

(6.17)

where

N

i

is the number of i-type vehicles by one lane

L is the span of the bridge

γ

i

is the mix ratio of i-type vehicles

L

Vj

is the length of j-type vehicles

L

H

is t