A Survey User Acceptance for Congestion Countermeasures atExpressway Sag Sections by Utilizing V2I Communication
Koichi Iwatake, Kazufumi Suzuki, Hideyuki Kanoshima, Hiroshi Makino
ITS Division, National Institute of Land and Infrastructure Management
Asahi1, Tsukuba City, Ibaraki Pref.
TEL 029-864-4496, FAX 029-864-0565
iwatake-k924a@nilim.go.jp suzuki-k92td@nilim.go.jp kanoshima-h92ta@nilim.go.jp
makino-h87bh@nilim.go.jp
ABSTRACT
Although traffic congestion around toll gates has been reduced with the popularization ofETC units for the Japan’s expressways, congestion arising on sag sections corresponds toapproximately 60% of all the congestion occurring on expressways, such that the devising ofeffective countermeasures is seen as being a priority. In this paper, we studied the attitudes ofexpressway users towards the efficacy of lane utilization optimization service and vehicle tovehicle gap optimization services as measures for mitigating congestion, and examined theirdegree of understanding.
Keywords: ITS, Lane Utilization Optimization, ACC, C-ACC
1. INTRODUCTION
Approximately 60% of the congestion occurring on the expressways connecting the cities ofJapan occurs in sag sections. NILIM is conducting research on resolving congestion at sags
using vehicles equipped with ACC (Adaptive Cruise Control), which maintains a constantinterval between vehicles. Some of Japan’s automotive manufacturers are developing CACC
(Cooperative Adaptive Cruise Control), which more precisely maintains intervals vehicles
using vehicle to vehicle communication.
At ITS World Congress Tokyo 2013, held at Tokyo Big Sight in October 2013, we invited
congress participants to test drive on expressway to show lane utilization optimization services,and vehicle interval optimization services using ACC and CACC. In addition, after the test
drive, we conducted a questionnaire survey related to traffic smoother services to verify thelevel of receptivity to such services, such as the effectiveness of such services for solving
congestion, the level of understanding of the services, and the inclination to cooperate withmitigate congestions. In this paper, we report the verification results.

2. Survey Method
At ITS World Congress Tokyo 2013, we invited congress participants (referred to below as“passengers”:They rode with a car.) to test drive of vehicles equipped with ACC and CACC toexperience its performance and information related to traffic smoother services provided fromthe ITS spots. Specifically, we first showed test drivers an orientation video (Figure 1) related
to congestion mechanisms at sags and traffic smoother services before departing from Tokyo
Big Sight. The vehicles followed the Bayshore Route from Rinkai Fukutoshin IC to Haneda
Airport IC, turning around in the Haneda Airport parking lot before returning to Tokyo Big
Sight. This demonstration was conducted using three ACC-equipped vehicles and four CACCequipped vehicles (three vehicles for testing and one lead car). Each demonstration had twopassengers per vehicle. Figure 2 shows an overview of the demonstration, including the driving
route, service data provided on the metropolitan expressway and the locations at which
information was provided. This figure shows the provided services for the outbound (RinkaiFukutoshin IC -> Haneda Airport IC) ACC-equipped vehicle and an inbound (Haneda IC ->Rinkai Fukutoshin IC) CACC-equipped vehicles.

Figure 1. Orientation video content.

TokyoFigure 2. Outline of the demonstration.

Passengers riding the ACC-equipped vehicles on the outbound route had lane utilization
optimization services and vehicle interval optimization services by ACC. On the return route,
they had vehicle interval optimization services by CACC. Passengers of the CACC-equippedvehicles on the outbound route had vehicle interval optimization services by CACC, and thenhad lane utilization optimization services and vehicle optimization services by ACC on thereturn route. After arriving at Tokyo Big Sight, they were given a questionnaire regarding theirlevel of understanding of the services they experienced.
3. Questionnaire Survey Results
3.1 Verifying Level of Understanding of Traffic Smoother Services and Inclination
to Participate in Congestion mitigated
The survey was conducted over three days with a total of 90. The professions of them areshown in Figure 3. Since this survey was conducted at the ITS World Congress, therespondents also included participants from abroad. In addition, because persons related to theautomotive and telecommunications industries comprised approximately 60% of the passengers,
many participants understood traffic smoother services. 11% of passengers were age 20–29,23% were age 30–39, 33% were age 40–49, 27% were age 50–59, and 6% were age over 60.
A-1.Please tell us about yourself.

A-1.Please tell us about yourself.

AgeOccupation

Teens

Student

60s or older

0%

Others
15%
Media

0%

6%

Professor

20s

6%
Government

11%

13%

50s
30s

27%

11%

23%

Telecom
14%

Automobile
42%

40s(n=88)

33%(n=87)

Figure 3. The Passenger professions.
Effectiveness for countering congestion traffic smoothing service at highway sags.
④Somewhatineffective

Figure 4 shows the answer on effectiveness oftraffic smoother services at countermeasures forcongestion at highway sags. 95% of passengers
answered either “1. effective” or “2. somewhateffective.”On the other hand, the passenger answered “4.
Somewhat ineffective” (N=1) . Next, we discuss
the level of understanding of the three services
Figure 4. Effectiveness of traffic smoother services.
test drivers experienced in this test: “laneutilization optimization services,” “ACC vehicle interval optimization services,” and “CACC
vehicle interval optimization services.”③Unsure1%⑤Ineffective

4%0%②Somewhat
effective
42%①Effective
53%(n=85)

In “lane utilization optimization services,” 97% of passengers answered either “I understand”
or “I somewhat understand.”On the other hand, 1% of passengers answered “I don’t
ACC Vehicle interval optimization service associated with ITS spots
understand”. Figures 5, 6 show the level of④I don't

understanding of each service that is “ACC
vehicle interval optimization services” and“CACC vehicle interval optimization services.”
In “ACC vehicle interval optimization services”,
94% of passengers answered either “1. Iunderstand” or “2.I somewhat understand”. On
the other hand, 1% of passengers answered “Idon’t understand”. Next, In “CACC vehicle

somewhat
understand.

⑤I don't

0%understand.

③Unsure.

1%

5%②I somewhat
understand.
18%①I understand.
76%

interval optimization services”, 98% ofpassengers answered either “1.I understand” or“2.I somewhat understand”. On the other hand,
1% of passengers answered “I don’t somewhatunderstand”.

(n=87)

Figure 5. Receptive for ACC vehicle interval
optimization services.
CACC vehicle interval optimization service associated with ITS spots④I don't
3.2 Verifying Inclination to Introduce
somewhat
ACC and CACC
understand.
③Unsure.
⑤I don't
1%
In this survey, we verified intent after1%
understand.
0%
informing the passengers that ACC and②I somewhat
CACC systems cost approximately 200,000
understand.
15%
yen. Figures 7 and 8 show the verification①I understand.
results.
83%
In inclination to purchase ACC, 90% ofpassengers answered “1.I would like to useit.” Or “2.I would somewhat like to use it”.
(n=88)
Most passengers answered that they wouldFigure 6. Receptive for CACC vehicle interval
like to introduce it “because it would be useful
optimization services.
for long-distance driving.” The next highest
reasons were “it would be effective for mitigate congestion” and “it would be effective forpreventing accidents.” Passengers expect ACC to function in terms of comfort, trafficsmoothing, and safety.

Would you be intereseted in purchaging and using ACC？
④I would be
unlikely to use it.
0%④I would be
unlikely to use it.
3%⑤I would not use it.
1%③Unsure.
8%②I would
somewhat like touse it.
28%

Would you be intereseted in purchaging and using CACC？

⑤I would not use it.
1%③Unsure.
7%②I would
somewhat like to useit.
33%①I would like touse it.
63%①I would like to useit.
56%(n=85)(n=86)

Figure 7. Inclination to purchase ACC.

Figure 8. Inclination to purchase CACC.

Next, inclination to purchase CACC, 89% of passengers answered “1.I would like to use it.” Or“2.I would somewhat like to use it”, regardless of occupation. Most passengers answered thatthey would like to introduce it “because it would be effective for mitigate congestion.” The
next highest reasons were “it would be effective for preventing accidents” and “it would behelpful for driving during congestion,” in that order. As ACC, passengers expect CACC tofunction in terms of comfort, traffic smoothing, and safety.
4. Verifying Effective Consciousness for Traffic Smoother Services/ Level ofUnderstanding of Vehicle Interval Optimization Services and Inclination to Introduce
ACC and CACC
We verified the trend that is effective consciousness for traffic smoother services/ level ofunderstanding of vehicle interval optimization services and inclination to introduce ACC andCACC using for cross tabulation. This verifying is that passengers who think traffic smootherservices effective for mitigate congestion and understand ACC/CACC vehicle interval
optimization services wants to purchase ACC and CACC.
Figure 9, 10 show the relation of effective consciousness for traffic smoother services and thepurchase of ACC/CACC. Over 80% of passengers that answered “1.effective”,”2.somewhateffective” for traffic smoother services, answered “1.I would like to use it”,”2.I would like tosomewhat use it”. Passengers who think that traffic smoother services are effective forof traffic2%
mitigating congestions have positive Consciousness
smoother services.
1.Effective.
71%
24%
intentions to purchase ACC.
2%
Besides, over 85% of passengers
2.Somewhat effective.
47%
36%
17%
who answered
Inclination to purchase ACC
3.Unsure.
100%“1.effective”,”2.somewhat effective”
1.I would like to use it.
2.I would somewhat like to use it.
3.Unsure.
for traffic smoother services,
4.somewhat ineffective
100%
4.I would be unlikely to use it.
5.I would not use it.
answered “1.I would like to use
0%
20%
40%
60%
80%100%it”,”2.I would like to somewhat use
Figure 9. The trend of consciousness of trafficit”. Passenger who thinks that trafficsmoother services and inclination to purchase ACC

smoother services are effective formitigating congestion have positive
intention to purchase CACC.
Figure 11 shows that the trend ofreceptiveness for ACC vehicle
interval optimization service andinclination to purchase ACC, andFigure 12 shows that the trend ofreceptiveness for CACC vehicle

Consciousness of trafficsmoother services.

2%

1.Effective.

67%

7%

24%

3%
2.Somewhat effective.

40%

3.Unsure.

6% 6%

46%

33%

67%

Inclination to purchase CACC
1.I would like to use it.
2.I would somewhat like to use it.
4.somewhat ineffective

3.Unsure.

100%

4.I would be unlikely to use it.
5.I would not use it.
0%

20%

40%

60%

80%

100%

Figure 10. The trend of consciousness of trafficsmoother services and inclination to purchase CACC

interval optimization service andinclination to purchase CACC.
Over 80% of passengers who answered “1.I understand”,”2.I somewhat understand” for ACC
vehicle interval optimization, answered “1.I would like to use it”,”2.I would like to somewhat
use it”. Passengers think that traffic smoother services are effective for mitigating congestions
have positive intensions to purchase ACC.
On the other hand, passengers who answered that “1.I understand.” for ACC vehicle interval
optimization answered “5. I would not like to introduce it.” He gave reasons such as “I havedoubts about the reliability of the devices” and “the system is still insufficiently precise at thistime.”
Besides, over 80% of passengers who answered “1.I understand”,”2.I somewhat understand”
for CACC vehicle interval optimization, answered “1.I would like to use it”,”2.I would like tosomewhat use it”. Passengers who think traffic smoother services are effective for mitigating
Consciousness of traffic2%smoother services.
congestions have positive6%
1.I understand.
69%
23%
intentions to purchase CACC.
On the other hand, some
2.I somewhat understand.
14%
64%
21%
passengers who answered that “1.I
3.Unsure.
100%
understand.” for CACC vehicle
Inclination to purchase ACC
1.I would like to use it.
interval optimization answered “4.
2.I would somewhat like to use it.
3.Unsure.
5.I don't understand.
100%
4.I would be unlikely to use it.
I would be unlikely to use it,” “5. I
5.I would not use it.
0%
20%
40%
60%
80%
100%
would not like to introduce
Figure 11. The trend of receptiveness for ACC vehicle intervalit.”
optimization service and inclination to purchase ACC
Reasons given included“because the devices are expensive” and “the system is effective only when other cars are also
equipped with CACC, so I would like to introduce it once the system has spread” and “because
CACC equipped vehicles are not currently in use, I would not like to introduce the system inthe initial stages.”
According to the above results, in this verifying, it was confirmed that most of passenger havepositive ideas for traffic smoother services and have intentions to purchase ACC/CACC.

On the other hand, some participants
have concerns on systems reliability
and effectiveness at the initial phase

Consciousness of trafficsmoother services.

1%

1.I understand.

63%

2.I somewhat understand.

25%

17%

6%

4%

17%

67%

when the systems are not widely spread.
5. Summary and Future Work
We found the survey revealed thatmost of participants have positive ideasfor traffic smoothing services
through the test ride on actual

3.Unsure.

100%
Inclination to purchase CACC

4.I don't somewhat
understand.

100%

0%

20%

40%

60%

80%

100%

1.I would like to use it.
2.I would somewhat like to use it.
3.Unsure.
4.I would be unlikely to use it.
5.I would not use it.

Figure 12. The trend of receptiveness for CACC vehicle interval

optimization service and inclination to purchase CACC
roadways. One of the reasons
may be that most participants belong to automotive and telecommunications industries and arefamiliar with the systems.
On the other hand, it will be necessary to modify the services so as to be easily understood byordinary people as some test drivers could not understand the contents of the systems.
Also, it was confirmed that the passengers confirmed to have positive ideas for traffic smootherservices and have intentions to purchase ACC/CACC.
However, it is necessary to improve the reliability of the systems and ACC/CACC as somepassengers have concerns on it. Also the spread of CACC will be desirable so as that vehicle tovehicle communication functions between vehicles equipped with the device. For that, themerit of ACC and CACC should be promoted in terms of traffic smoothing and safety and theirprice should be affordable.