child pedestrians’ crossing gap thresholds

CHILD PEDESTRIANS’ CROSSING GAPTHRESHOLDS

Student：董瑩蟬

Purpose• This paper investigated the child on the

road crossing distance gap.

• Child divide to three group, they are 5-6, 8-9 and 11-12.

• At the same time examine gender effect road crossing behavior.

• And they investigated factor effect road crossing decision.

Reference-about accident• Many countries data showed the child (5-7 year

s) that has higher risk on the road. (Howarth et al.,1974； Robert, 1994 an so on.)

• Pedestrian accidents often at between 8 to 9 A.M and between 3 to 4 P.M. (Land transport safety Authority, 1992)

• Jones et al. (1988) found that the boy accident higher than girls.

Reference-about decision

• Siegler et al. (1979) found that the child has difficult in decision traffic situation speed and distance.

• The 5 years child can’t catch on the speed and distance, and the 8-11 child has confusion on it. (Shinar, 1978)

• Some studies found that the adults has difficult to decision gap.

Reference-distance• Children decision gap rely on distance. (Vinj

e, 1981)

• Some studies used simulated investigate road crossing gap. (Lee et al.,1984; young et al., 1987)

• Connelly et al.,(1996) the pedestrian decision crossing rely on distance not vehicle speed.

Method

• Subjects– 48 people divided to three group, each group was 8 boys

and girls– The age group was 5-6, 8-9 and 11-12 years old.

• Equipment– Keystone VS-II Vision Screener Model 1135A– Beltone Model 109 portable audiometer– (Marksman/LTI 20:20; Laser Technology Inc.,

Englewood, CA,U.S.A.)

Method• Independent variable

– Age– Gender– Speed category:0-50, 51-55, 56-60, 61-65, 66+

• Dependent variable– Road crossing time– Vehicle speed data– Distance gap threshold judgements– Safe distance indices

Method• Process

• The first was measure child and parents vision and hearting.

• The second, require child crossing the road (12 m) and collect the road crossing time.

• The experiment start, the child completed 10 trials.

childparents

1m

2 m

4 m

Vehicle

Method• Process

• The vehicle closed child and when the car flashed headlight the assistant instruct child look traffic situation.

• When the trial start the child must keep looking at traffic situation. At the same time speak yes,yes… ,if they feeling can safety crossing. And when they think they can’t safety crossing, they say no immediately.

• When the child say no, the assistant used laser get distance (between vehicle and child) and vehicle speed.

Result-Road crossing• The mean road crossing gap: Age second 5-6 3.16 8-9 2.84 11-12 2.77

• ANOVA result found age on the road crossing time has significant different.(F(2,474)=34.21,p<0.01)

• LSD found

5-6 8-9 11-12

• The gender significant different crossing time only on the 11-12 group. (P<0.005)

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Result-Vehicle speed data• The speed between 26 to 78 Kph (mean=53.8 k

ph, S.D=7.23)

• The oncoming vehicle speed divided to five range:

speed percentage 0-50 31 51-55 30 56-60 23 61-65 10 66+ 6

39%

Result-Distance gap threshold judgements

Fig. 1. Mean and SD of the distance gaps allowed by all participating children in each of the five vehicle speed categories.

Result-Distance gap threshold judgements

• The mean distance gap threshold was between 10 to 146 meter. (mean=64.6 meter, S.D=29.3 meter)

• The vehicle has no significant different on the mean distance gap threshold.(F(4,475)=0.6, P<0.005)

Result-Distance gap threshold judgements

Result-Distance gap threshold judgements

• The age group has significant different on the mean distance gap. (F(2,472)=9.02, P<0.01)

• The age and gender has interaction on the mean distance gap. (F(2,476)=7.32, P<0.01)

• The age and speed has interaction on the mean distance gap. (F(8,471)=2.14, P<0.05)

• The LSD analysis result found the distance different:

• 5-6 8-9 11-12

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Result-Safe distance indices

Fig. 2. Mean and SD of the safe distance index data (metres) for the five vehicle speed categories by age group and gender. Negative values indicate unsafe decisions.

Result-Safe distance indices• Safe distance index (m)= distance gap

threshold-vehicle speed (m / s) * mean crossing time

• We can conclusion the lower vehicle speed, the safe distance index increased.

• ANOVA analysis result found that the age has significant different on the safe distance index. (F(2,450)=7.59, P<0.001) And similar to speed rang F(4,450)=7.38, P<0.01

Result-Safe distance indices• They found interaction between age and

gender (F(2,450)=4.82, P<0.01), and similar to age and speed rang F(8,450)=2.11, P<0.05

• The LSD analysis result found

5-6 8-9 11-12

• Post hock test

• 0-50 51-55 56-60 61-65 66+

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Result-Safe distance indices

Fig. 3. Means and SDs of both the safe distance index ( left scale) and the safe time index (right scale) data for all participating children in each of the five vehicle speed categories.

Result-Safe distance indices

• The mean safe distance index from 28.2 m (0-50 Kph situation) to 8.9 m (66+ Kph situation).

• The safe time index from 2.24 seconds (0-55) to 0.47 second (66+).

Result-Percentage of safe crossing gap threshold judgements

• At total 480 trials, the research found 74% able to safe crossing road.

• At different group distribute follow: age gender percentage

5-6 B 70 G 62.5 8-9 B 62.5 G 65 11-12 B 95 G 88

Result-Percentage of safe crossing gap threshold judgements

• The boy safe crossing percentage higher than girl.

• The age under 10 years older risk higher than 11-12 age group.

Result-Factors influencing safe crossing gap threshold

• There are 63 % decision the road crossing rely on distance.

• There are 10% road crossing judgement basis of vehicle speed.

• 19% subject decision rely on both vehicle speed and distance.

• There are 8% subject can’t explain the decision reason. (three from 5-6 group and one from 8-9 group)

Discussion• This paper result found that the under 10 y

ears has poor skill on road crossing, and pedestrian rely on distance. Similar to Connely et al.(1996) and Siegler et al.(1979).

• Hills(1980) and Parsonson et al.(1996) similar found on adult.

Conclusion

• The lower vehicle speed, the safe distance index increased.

• The 5-6 years older child was the slower pedestrian.

• The child cross road rely on distance, but not coming vehicle speed.

• The boy has higher safe crossing road percentage than girls.

My comment• The child cross road rely on distance.

There are many studies found that. For example Jennifer et al.(2006), Gordon et al.(2003) and Jennifer A.(2005).

• Child pedestrian related studies, for example Gordon et al.(2003) also investigated child and younger.