Driver Attention for Information Display on Variable Message Signs with Graphics and Texts

Driver Attention for Information Display on Variable Message Signs

with Graphics and Texts

Chien-Jung Lai, Chi-Ying Wang

National Chin-Yi University of Technology, Taiwan.

IFORS 2014 Barcelona

Introduction

Experiment Method

Results and Discussion

Conclusions4

1

2

3

Outlines

What are Variable Message Signs (VMS) and Graphical Route Information Panel (GRIP)?

Types of GRIP in the World

Advantages and Disadvantages of GRIP

Objectives


GRIP are a category of variable message signs (VMS) in Intelligent Transportation Systems to display real-time congestion and journey time information with graphics relevant to drivers on sections of the trunk road network.

Alternative names of GRIP:

• Graphical Congestion Display Panels (GCDP) in the UK.

• Changeable Graphical Signs (CGS) in Taiwan.

Introduction –What are Variable Message Signs (VMS) and

Graphical Route Information Panel (GRIP)?


Introduction – Types of GRIP in the World


Display information regarding different routes simultaneously.

• By displaying part of a road network, including the location of congestion, an overview of the current traffic situation can be given.

Serve a larger group of motorists

• Particularly motorists who are not familiar with the roadways will have fewer problems.

Introduction – Advantages of GRIP


A problem that remains is whether or not more information can be processed fast enough by drivers, and how complex the GRIPs can be for the motorist while negotiating an everyday road situation.

Integration of GRIP and VMS may be an alternative for improving the effectiveness of traffic variable signs.

Introduction –Disadvantages of GRIP


Investigate the effects and driver attention of display information and position on Variable message signs (VMS) with graphics and texts.

Introduction – Objectives


road colorroad color with driving

journey time

Independent Variables

• Content of GRIP information (road color, road color with driving journey time)

Methods – Experiment Design



• VMS information (no information, simple information, detailed information)


no information simple information detailed information



• Position of VMS relative to GRIP (top, bottom, right, left)


top bottom

right left



A within-subjects design was conducted in the experiment. 24 treatment groups represented the combinations of the three within-subjects factors.

Each participant went through 72 randomized stimulus presentations, that is, 24 GRIP with 3 different response choice in each test.


Illustrations of 3 VMS information and 4 positions under different GRIP information


VMS information

Position of VMS relative to CGS

Noinformation

Simpleinformation

Detailinformation

Top

Bottom

Left

Right

(a) GRIP with road colour only information


Illustrations of 3 VMS information and 4 positions under different GRIP information


VMS information

Position of VMS relative to CGS

Noinformation

Simpleinformation

Detail information

Top

Bottom

Left

Right

(b) GRIP with road colour and driving journey time information


The VMS+GRIP are merged with driving video simulating a driver’s view.

A sequence of computer generated VMS+GRIP is projected onto a screen in a random but controlled manner.

Participants sitting in front of the screen sees the messages gradually increase in size.

Participants were asked to choose a route according to the assigned destination by their free will.

An appropriate action (turn the steering wheel or press the pedal) is required to signal subject’s comprehension of the stimulus information.

Method – A Video-based Driving Simulation


Method – Experiment set-up

15 15


An example of three different GRIP with the associated optimum response mode.

GRIP

Optimum route choiceResponse mode

Driving straight Press right pedal

Turn left Turn the wheel left

Turn right Turn the wheel right

Method – Respond mode

*The optimum response is the choice to the fastest route among all alternatives.


Response time the time between the start of presentation of a GRIP with VMS stimuli and the moment of a participant’s response to the information.

Optimum route choice percentage100 times the number of optimum responses divided by the total number of responses.

Method- Performance measure


30 students were chosen randomly from the college.

• Gender -15 males, 15 females.

• Age – 19~28 yrs., M=23, SD=3.1

All were with valid driver’s licenses and had driving experience on freeways.

Method – Subjects


Result & Analysis- Performance under each level of the IDVs

Independent variables n

Response time (sec.）

Optimum route choice percentage (%)

Mean S.D. Mean S.D.

*Content of GRIP information

Color only 360 10.764 2.394 91.44 17.46

Color with journey time 360 11.403 2.259 90.12 18.18

Content of VMS information

No 240 11.037 2.376 90.56 17.08

Simple 240 11.059 2.405 90.63 18.83

Detail 240 11.154 2.267 91.15 17.58

*Position of VMS relative to GRIP

Top 180 11.275 2.424 91.71 17.50

Bottom 180 10.957 2.296 90.56 19.06

Left 180 10.233 2.396 90.09 18.20

Right 180 10.868 2.264 90.74 16.55


Result & Analysis- ANOVA Main Effect Plots of Significant Factors

Participants responded more quickly for road color only GRIP (10.764 s) than for road color with journey time GRIP (11.403 s). ( F(1, 29)=86.67, p<0.001)

Participants had the shortest response time for VMS on the right position of GRIP (10.868 s), the longest time for VMS on the top position (11.275 s). ( F(3, 87)=4.915, p<0.05)


Result & Analysis- INTERATION

• The interaction of content of VMS information and content of GRIP information were significant on participants’ response time ( F(2, 58)=7.925, p<0.05). Response times for none information with the road color only of GRIP were the shortest.


Result & Analysis- INTERATION

• The interaction of content of VMS information and position of VMS relative to GRIP were significant on participants’ response time ( F(6, 174)=4.092, p<0.05). Response times for none information with the right position of VMS relative to GRIP were the shortest.


Result & Analysis- Gaze trajectory

• In general, participants first gazed at GRIP, next shifted to VMS, and then fixed at GRIP again.


The content of GRIP information significantly affected participants’ response time. GRIP with road color only had quicker response time compared to road color with journey time.

Familiarity with color codes and less information units for GRIP with color codes should explain the effect. Color codes were better for identification task than were certain other codes (Christ, 1975; Sanders and McCormick, 1993).

The amount of information units for road color only was less than road color with journey time.

Discussion


The results also showed participants had the shortest response time for VMS on the right position of GRIP, and they had the longest time for VMS on the top position relative to GRIP.

Participants’ response times for VMS on the right position relative to GRIP was the shortest while VMS had none information.

Order of participants’ gaze may explain some of the effects.

Discussion


Considering drivers’ comprehension and response, using colour to present the traffic condition on GRIP may be a suitable method.

Right position of VMS relative to GRIP may also be a better allocation of VMS and GRIP panel.

A further research on eye fixation and gaze trajectory for understanding the allocation of drivers’ attention is needed.

Conclusions


Thank You!


Driver Attention for Information Display on Variable Message Signs with Graphics and Texts

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