1. Effects on driving behavior of congestion information and of scale of in-vehicle navigation systems Author: Shiaw-Tsyr Uang, Sheue-Ling Hwang Transportation Research Part C 11 (2003) 423–438 Reporter: Yang Kun Ou

2. Purpose The purpose of this research was to compare the usage of a traditional paper map and electronic route maps during driving, and to consider the effects of congestion information and map scale sizes on driving performance, workload and subjective feelings.

3. Reference When one driver is driving in familiar areas, s/he often navigates from the origin to the destination according to his or her pre-built cognitive map. Navigation, in this case, depends mostly on route or survey knowledge rather than landmark knowledge (Wickens, 1992). drivers who were familiar with the road network had less difficulty in finding destinations and drove shorter duration routes than drivers who were unfamiliar with the road network (Eby and Kostyniuk, 1999).

4. Reference Hughes and Cole (1986) have found that from 30% to 50% of drivers visual attention may be allocated to things unrelated to the driving task, and thus using the electronic map while driving is not necessary to decrease driving performance. Hughes and Cole (1986) have found that from 30% to 50% of drivers visual attention may be allocated to things unrelated to the driving task, and thus using the electronic map while driving is not necessary to decrease driving performance.

5. Reference when information complexity increases, the drivers glance duration and frequencies increase, and thus increase the potential driving hazard and/or driver workload (Dewar, 1988; Dingus and Hulse, 1993; Wierwille, 1993)

6. Methods of the Experiment I Subjects Subjects A total of 20 undergraduate students (15 males and 5 females). Half of the participants had drivers licenses Subjects age ranges from 20 to 23 years old (mean=22, SD=0.97) Subjects reported they understand the experimental procedures completely (mean=1.40, SD=0.82) and highly devoted themselves to the experimental tasks (mean=1.45, SD=0.76)

7. Apparatus The driving simulator The driving simulator 17-in & 14-in color monitor 17-in & 14-in color monitor The Virtual environment development software The Virtual environment development software (3D Webmaster version 5.5) (3D Webmaster version 5.5)

8. Experimental design Two within-subjects factors (availability of congestion information and scale sizes) were used to construct four electronic route map conditions in this study map A as small-scale without congestion information map B as small-scale with congestion information map C as large-scale without congestion information map D as large-scale with congestion information A traditional paper map usually without congestion information was also used as one of the map conditions.

9. Experimental design cont. All subjects experienced these five conditions in a randomized sequence to counterbalance the possible learning or fatigue effects. Five conditions were tested in different driving scenarios to avoid memory effects These five driving scenarios have equal trip length

10. Independent variables The independent variables of the present study were the availability of congestion information and the scale sizes of maps A large-scale map could display the view of 3–4 blocks A small-scale map showed the view of nearly two blocks

11. Dependent variables The criteria of driving performance were trip duration, driving speed, number of navigation errors Included heart rates to represent the degrees of workload (Myrtek et al., 1994) and subjective ratings to show perceived nervousness, fatigue and task difficulty toward different experimental conditions. (Likert-type scale)

12. Result A traditional paper map vs. electronic maps The paired t tests were conducted to compare the subjective feelings between using a paper map and using four electronic maps. No significant difference was found between the paper and electronic maps (t =0:684, 0.428, 0.804, p =0:503, 0.674, 0.431) The average heart rate when driving and using a paper map was 80.1 per min, and 79.6 per min when deiving and using electronic maps

13. Result A traditional paper map vs. electronic maps the driving performance of using a paper map and the average driving performance of using four electronic maps. The results revealed that there was no significant difference in trip duration and driving speed while using these two kinds of maps during driving (t=-1.691, 0.655, p=0.107, 0.520, respectively).

14. Result A traditional paper map vs. electronic maps One map with an electronic visual display function will not guarantee its navigation efficiency, but how an electronic map is designed and what kind of information is provided on the map may result in totally different effects.

15. Result Trip duration Two significant main effects of congestion information and scale size were found on trip duration (F=10.108, 21.450, p=0.005, 0.000, respectively).

16. Result Using electronic route maps with congestion information may shorten the trip duration than using those maps without this information small-scale electronic maps were superior to large-scale ones in terms of trip duration.

17. Result The total number of navigation errors while using four electronic maps The total number of navigation errors while using four electronic maps

18. Result The average and maximum heart rates while using four electronic maps The average and maximum heart rates while using four electronic maps

19. Methods of the Experiment II The small-scale electronic maps (1–2 blocks) may have better performance than the large- scale ones (3–4 blocks) The Experiment II was conducted to further explore the influences of map scale.

20. Methods of the Experiment II Subjects Subjects A total of 18 undergraduate students (9 males and 9 females) Eight participants have drivers licenses Subjects age ranges from 19 to 23 years old (mean=21, SD=1.1)

21. Experimental Procedure One electronic route map showed the view within one block, and the other map could display the view of nearly 1–2 blocks. Subjects experienced these two conditions in randomized sequences

22. Result Reducing map scale from 1–2 blocks to less than one block provides no additional benefits in consulting the electronic maps and/or detecting a stimulus.

23. Discussion By which the driver may plan the upcoming maneuvers in advance (Streeter et al., 1985) as well as build-up route or survey knowledge easily (Wickens, 1992). In other words, the drivers in past studies preferred a larger scale The usage of navigation systems with traffic congestion information could enhance route selection quality and result in better driving performance for a particular driving journey (Stern, 1999)

24. Conclusion In-vehicle navigation systems with traffic congestion information may improve the route selection quality in terms of shorter trip duration and fewer navigation errors.