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
PurposePurpose
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.
ReferenceReference When one driver is driving in familiar areas, s/he ofte
n 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).
ReferenceReference
Hughes and Cole (1986) have found that from Hughes and Cole (1986) have found that from
30% to 50% of drivers visual attention may be 30% to 50% of drivers visual attention may be
allocated to things unrelated to the driving allocated to things unrelated to the driving
task, and thus using the electronic map while task, and thus using the electronic map while
driving is not necessary to decrease driving driving is not necessary to decrease driving
performance. performance.
ReferenceReference
when information complexity increases, the dri
vers glance duration and frequencies increase,
and thus increase the potential driving hazard a
nd/or driver workload
(Dewar, 1988; Dingus and Hulse, 1993; Wierw
ille, 1993)
Methods of the Experiment I
SubjectsSubjects• 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)
ApparatusApparatus
The driving simulatorThe driving simulator
17-in & 14-in color monitor 17-in & 14-in color monitor
The Virtual environment development softwareThe Virtual environment development software
(3D Webmaster version 5.5)(3D Webmaster version 5.5)
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.
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
Independent variables The independent variables of the present study were t
he availability of congestion information and the scale sizes of maps• A large-scale map could display the view of 3–4 bl
ocks• A small-scale map showed the view of nearly two
blocks
Dependent variablesDependent 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)
ResultResult
A traditional paper map vs. electronic maps The paired t tests were conducted to compare the subj
ective 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
ResultResult
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).
Result 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.
ResultResult
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).
ResultResult 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.
ResultResult
The total number of navigation errors while The total number of navigation errors while using four electronic mapsusing four electronic maps
ResultResult
The average and maximum heart rates while The average and maximum heart rates while using four electronic mapsusing four electronic maps
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.
Methods of the Experiment II
SubjectsSubjects• 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)
Experimental ProcedureExperimental 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
ResultResult
• 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.
DiscussionDiscussion
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)
ConclusionConclusion
In-vehicle navigation systems with traffic
congestion information may improve the route
selection quality in terms of shorter trip
duration and fewer navigation errors.