Research Trends and Results
Exhaust Gas Characteristics of Freight Vehicle on the Real RoadKADOYU Katsunori, HeadDOHI Manabu, Senior Researcher
SUGABAYASHI Keita, Guest Researcher
Road Environment Division, Environment Department(Key words) motor vehicle emissions, carbon dioxide(CO₂), nitrogen oxide(NOx), on-board emissions

measurement system
1. Introduction
Among the loads on environment by motor vehicles inJapan, the influence by freight motor vehicles and buses
take 40% in CO₂ and 80% in NOx. So it’s important tounderstand the actual conditions of exhaust emissions on
the real road. Therefore, how to understand the influence
coming from driving on real roads was an issue.
In this investigation, on-board emission measurement
system was used for analysis of exhaust gas.

fixed velocity. (reference figure-2)

20%

750

0500

‐10250‐2002.0

NOX排出量（g/km）

10Compared to a diesel vehicle,
a gasoline vehicle’s NOx
emissions are low.

1.5

4%

3%

アイドリング

38%

53%

22%

加速運転
accelation

定速運転
fixed
speed

55%

減速運転
deceleration

Figure 2. The ratio of Driving Time, Exhaust Amountof CO ₂ ,NOx (Heavy Freight Motor Vehicle 20-25tClass---Diesel)
We showed the same kind of analysis result which
object was an ordinary motor vehicle (gasoline).
(figure-3) Compared with figure-2, the ratio of hourly
exhaust amount of CO₂, NOx while idling was greater.
From this viewpoint, the idling stop measure for cars wasdeduced to be effective.
15%

NOx emissions

CO2 emissions

Driving time

6%

4%

13%

18%
19%

48%

48%

アイドリング

加速運転
accelation

41%

35%

53%

fixed
speed
定速運転

減速運転
deceleration

Figure 3 The ratio of Driving Time, Exhaust Amountof CO₂,NOx (car-gasoline)

1.0
0.5

20-25t Class freightmotor Vehicle（ Diesel）

Microbus（ Gasoline）

4-5t Class freightmotor Vehicle（ Diesel）

Medium Class freightmotor Vehicle（ Gasoline）

Medium Class freightmotor Vehicle（ Diesel）

0.0

NOX emissions

2%

41%

走行時車両重量（t）

CO2 排出量（g‐CO 2 /km）

CO2 Emissions (g-CO2/km) NOx Emissions(g/km)20

定速約30km/h（試験走路）
Fixed speed of 30km/h (test road)
平均旅行速度約30km/h
Average driving speed of 30km/h(real road)
Weight of freight motor vehicle
走行時車両重量4%

21%

37%

2.

1000

CO2 emissions

Driving time

Weight of freight motor vehicle (t)The Summary of the Results
This analysis was executed under 2 conditions. One
was measured on test road, the other one is on real road.
As the result of experiments, amount of emissions ofCO₂ by real road traffic was more than that of test roadtraffic. (reference figure-1). After analyzing the data, thisdifference comes from the influence of acceleration anddeceleration on the real road.

discharged twice the CO2 emissions compared to that ofFigure 1 Exhaust Amount of CO₂,NOx
3. Grasp of Exhaust Gas Characteristics
According to the analysis of the driving time andexhaust gases of 20-25t class heavy freight motor
vehicles (diesel), during acceleration the vehicle

4. Conclusion
From the investigation, we clarified that the exhaustgas characteristics differs by the kinds of motor vehicle,
especially the acceleration of freight motor vehicle havethe great influence on the exhaust amount of CO₂ , NOx.
Because those vehicles need time and driving power toaccelerate them.