Drivers’ speed behaviour at a zebra crossing: a case study

學生：董瑩蟬

Purpose• This paper have four purposes:

– Observe frequency of pedestrian crossing zebra.

– Driver’s speed adjusted problem.– The pedestrian crossing whether or not effect

driver’s speed.– Identify the ideal situation (driver brakes

provide way to pedestrian)

Reference• There were 36% injury accidents between

vehicle and pedestrian. The accident occurred at pedestrian crossings. (SCB,1996)

• The vehicle speed 50 km/hr that the collision higher than vehicle speed 30 km/hr. The different about 8 times. (Pasanen,1992)

• Engel and Thomsen (1990) found that the speed may effect pedestrian safety.

Reference• Some studies found that only 30%, 4-6% a

nd 24% of the drivers gave priority to pedestrians at zebra crossings. (respectively Danielsson et al.,1993; Trafikkontoret, 1994; Hyden et al.,1995)

• Himanen and Kulmala (1988) found that the most factors effect drivers’ behavior. For example pedestrian distance from the curb, size of the city, number of pedestrian and

vehicle speed ect.

Theoretical Framework

Method• Observed site

– The site was an non-signalize and no central island. The width of the road is 7m.

– Daily traffic was 8800 vehicle, average 243 car/hr. Speed limit 50 km/hr.

– Pedestrian average 28 /hr for left. Right was 35/hr

– the driver can see pedestrian about 8m on the road left (driver ca 6 second arrived), right was 10m(7second).

– Observation time from 9:00 to 11:30 and from 13:00 to 15:00

Method• Observed situation

– Total 1480 situation– 690 times no pedestrian– 324 times the pedestrian from left crossing– 466 times the pedestrian from right crossing

• Equipment– Radar gun: record the driver speed.– Computer– Video recordings: collect detailed behavior

between car and pedestrian.

Method• Independent variables

– Whether or not pedestrian– Pedestrian location left or right

• Dependent variables– Time-to-zebra (TTZ): see fig 3– Time to accident: remains from the start of

evasive action until the collision would have occurred

– Post-encroachment-time (PET): see fig 2

Method: the time of pedestrian arrived other side

: the time of driver readiness to stop before the zebra crossing

Method• The interaction situation between car and

pedestrian:– pedestrian presence: the pedestrian at zebra

crossing when the approach vehicle is within 70 m from the zebra crossing

– Encounters between car and pedestrian: collision course, it assumed pedestrian speed of 1.4m/second.

– Conflicts : The TA values very low. It include road-users would collide if neither part took evasive action.

Result-pedestrian presence

Result-pedestrian presence• The mean speed has significance different

between pedestrian presence and no pedestrian. (t-test p<0.05)

• Pedestrian from left: (see fig 4)– The mean speed has no different between pedestrian

present and no pedestrian, when the pedestrian arrives at the zebra crossing <1 second.

– And the same with 1s<TTZ<2s and 2s<TTZ<3s.– The mean speed of pedestrian present has significance

higher than no present. when the pedestrian arrives at the zebra crossing 3<TTZ<4 second. That has 90% of the car first.

– The mean speed of pedestrian present has significance lower than no present. when the pedestrian arrives at the zebra crossing >4 second. In 15 of 203 was pedestrian first.

Result-pedestrian presence

Result-pedestrian presence• Pedestrian from right: (see fig 5)

– The mean speed has no different between pedestrian present and no pedestrian, when the pedestrian arrives at the zebra crossing <1 second.

– The mean speed of pedestrian present has significance higher than no present. when the pedestrian arrives at the zebra crossing 1<TTZ<2 second. The car passes in all.

– And the same with 2<TTZ<3. The pedestrian passes first only one.

– The mean speed of pedestrian present has significance higher than no present. when the pedestrian arrives at the zebra crossing 3<TTZ<4 second. There were four case the pedestrian passes first.

– The mean speed of pedestrian present has significance lower than no present. when the pedestrian arrives at the zebra crossing >4 second. In 15 of 282 was pedestrian first.

Result-Encounters

•There were 148 encounters, the pedestrian from left 105 times and right 43 times.•The mean speed between encounter and no encounter has significance different. (t-test, P<0.05 )•The highest mean speed was between 40-50m. The encounters mean speed significance higher than on encounters and no pedestrian.

Result-Encounters

•the speed variance is lower than both before and after section at the 50m section. Which might be indication the driver decision approach-strategy ca at this moment.

Result-Encounters

•The encounter mean speed significance higher than no pedestrian and non-encounter.

Result-Conflicts

Result-pedestrian priority• “No braking situations”

(22 cases)• The pedestrian presence

was 790 times. The pedestrian passes first were only 42 case.

• The pedestrian from the left arrives at the zebra crossing >5 second earlier and from the right >3.7 seconds earlier than the car.

• The PET values was over 2.2 second ,that is acceptable time gap.

Result-pedestrian priority• “provoked braking

situations” (12 cases)

• The pedestrian from the left arrives at the zebra crossing between 3.6 and 5.1 seconds earlier and from the right between 2.0 and 5.1 seconds earlier than the car.

• The driver start to break between 15 and 60m before the zebra crossing.

Result-pedestrian priority• “ideal” interaction (8 cases):

the car brakes provide pedestrian crossing way.

• The pedestrian from the left arrivers at the zebra crossing between 3.6 and 5.4 seconds earlier and from the right between 3.7 and 4.8 seconds earlier than the car. The car is >45 m away.

• The driver start to brake between 30 and 70m.

Discussion• The result showed that the driver to give w

ay to pedestrian at the zebra crossing is low. This result was different earlier studies. Dahlstedt (1994) used questionnaire to investigated that found the 67% driver responses they often or always give way to a pedestrian at pedestrian crossings.

Conclusion

• The pedestrian at zebra different may effect driver decision.

• The vehicle speed were different between pedestrians presence and no pedestrians.

• The driver to give way to pedestrian at the zebra crossing is low.