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 Conclusions 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 IFORS 2014 Barcelona

 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)? IFORS 2014 Barcelona

Introduction – Types of GRIP in the World IFORS 2014 Barcelona

 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 IFORS 2014 Barcelona

 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 IFORS 2014 Barcelona

 Investigate the effects and driver attention of display information and position on Variable message signs (VMS) with graphics and texts. Introduction – Objectives IFORS 2014 Barcelona

road color road color with driving journey time  Independent Variables Content of GRIP information (road color, road color with driving journey time) Methods – Experiment Design IFORS 2014 Barcelona

 Independent Variables VMS information (no information, simple information, detailed information) Methods – Experiment Design no informationsimple informationdetailed information IFORS 2014 Barcelona

 Independent Variables Position of VMS relative to GRIP (top, bottom, right, left) Methods – Experiment Design topbottom right left IFORS 2014 Barcelona

Methods – Experiment Design  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. IFORS 2014 Barcelona

Illustrations of 3 VMS information and 4 positions under different GRIP information Methods – Experiment Design VMS information Position of VMS relative to CGS No information Simple information Detail information Top Bottom Left Right (a) GRIP with road colour only information IFORS 2014 Barcelona

Illustrations of 3 VMS information and 4 positions under different GRIP information Methods – Experiment Design VMS information Position of VMS relative to CGS No information Simple information Detail information Top Bottom Left Right (b) GRIP with road colour and driving journey time information IFORS 2014 Barcelona

 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 IFORS 2014 Barcelona

Method – Experiment set-up 15 IFORS 2014 Barcelona

An example of three different GRIP with the associated optimum response mode. GRIP Optimum route choice Response 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. IFORS 2014 Barcelona

 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 percentage  100 times the number of optimum responses divided by the total number of responses. Method- Performance measure IFORS 2014 Barcelona

 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 IFORS 2014 Barcelona

Result & Analysis- Performance under each level of the IDVs Independent variables n Response time (sec. ） Optimum route choice percentage (%) MeanS.D.MeanS.D. *Content of GRIP information Color only Color with journey time Content of VMS information No Simple Detail *Position of VMS relative to GRIP Top Bottom Left Right IFORS 2014 Barcelona

Result & Analysis- ANOVA Main Effect Plots of Significant Factors  Participants responded more quickly for road color only GRIP ( s) than for road color with journey time GRIP ( s). ( F(1, 29)=86.67, p<0.001)  Participants had the shortest response time for VMS on the right position of GRIP ( s), the longest time for VMS on the top position ( s). ( F(3, 87)=4.915, p<0.05) IFORS 2014 Barcelona

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. IFORS 2014 Barcelona

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. IFORS 2014 Barcelona

Result & Analysis- Gaze trajectory In general, participants first gazed at GRIP, next shifted to VMS, and then fixed at GRIP again. IFORS 2014 Barcelona

 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 IFORS 2014 Barcelona

 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 IFORS 2014 Barcelona

 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 IFORS 2014 Barcelona

Thank You! IFORS 2014 Barcelona