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.